Chromosome 13, Partial Monosomy 13q

13号染色体长臂远端单体

Chromosome 13, Partial Monosomy 13q is a rare chromosomal disorder in which a portion of the long arm (q) of chromosome 13 is missing (deleted or monosomic). The range and severity of symptoms may vary greatly, depending upon the exact size and location of the deletion on 13q. Chromosome 13, Partial Monosomy 13q is usually apparent at birth and may be characterized by low birth weight, malformations of the head and facial (craniofacial) area, abnormalities of the eyes, defects of the hands and/or feet, genital malformations in affected males, and/or additional physical abnormalities. Affected infants and children may also exhibit delays in the acquisition of skills requiring the coordination of mental and muscular activity (psychomotor retardation) as well as varying degrees of intellectual disability. In the majority of cases, Chromosome 13, Partial Monosomy 13q appears to occur randomly, for no apparent reason (sporadic).

In Chromosome 13, Partial Monosomy 13q, a rare chromosomal disorder, a portion of the long arm (q) of chromosome 13 is missing (deleted). Symptoms and physical characteristics associated with the disorder may vary greatly, depending upon the exact size and location of the deletion (monosomy) on chromosome 13q.

Chromosome 13, Partial Monosomy 13q is a rare chromosomal abnormality in which a portion of the long arm (q) of chromosome 13 is missing (deleted). Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p and a long arm identified by the letter q. Chromosomes are further subdivided into bands that are numbered. For example, 13q32 refers to band 32 on the long arm of chromosome 13.

Chromosome 13, Partial Monosomy 13q appears to affect females slightly more frequently than males. Although rare, deletions involving chromosome 13q are among the most commonly observed monosomies. Since the disorder was originally reported in 1963, more than 125 cases have been recorded in the medical literature.

Symptoms of the following disorders can be similar to those of Chromosome 13, Partial Monosomy 13q. Comparisons may be useful for a differential diagnosis:

Chromosome 13 Ring is a rare chromosomal disorder in which chromosome 13 breaks at both ends (i.e., the ends of the long arm [13q] and the short arm [13p]). The chromosomal ends then join together, forming a ring. Affected infants often exhibit a low birth weight, growth deficiency, psychomotor retardation, and/or intellectual impairment. In addition, they may also have distinctive abnormalities of the head and facial (craniofacial) area such as an abnormally small head (microcephaly), a wide, flat nasal bridge, an unusually prominent upper jaw (maxilla); protruding front teeth (incisors), large, low-set ears, and/or other craniofacial malformations. In some cases, affected individuals may also exhibit abnormalities of the eyes, which may include retinoblastoma in some cases; genital malformations in males; trigonocephaly and/or brain malformations, skeletal abnormalities, congenital heart defects; and/or additional physical abnormalities. Most cases of Chromosome 13 Ring appear to be due to a spontaneous (de novo) genetic change (mutation) very early in embryonic development that occurs for unknown reasons (sporadic).

In some cases, the diagnosis of Chromosome 13, Partial Monosomy 13q may be determined before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). Ultrasound studies may reveal characteristic findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During amniocentesis, a sample of fluid that surrounds the developing fetus is removed and studied. During chorionic villus sampling, a tissue sample is removed from a portion of the placenta. Chromosomal studies performed on this fluid or tissue sample may indicate a partial monosomy of chromosome 13q.


Chromosome 14 Ring

Chromosome 14 Ring is a rare disorder that is characterized by abnormalities of the 14th chromosome. Affected infants and children typically have delays in the acquisition of skills that require the coordination of physical and mental activities (psychomotor delays), mental retardation, growth delays, and episodes of uncontrolled electrical activity in the brain (seizures). The disorder is also characterized by distinctive abnormalities of the head and facial (craniofacial) area. Such abnormalities may include an unusually small head (microcephaly) with a high forehead; an elongated face; widely spaced eyes (ocular hypertelorism); a thin upper lip; a flat nasal bridge with a prominent nasal tip; and large, low-set ears.

The symptoms and findings associated with Chromosome 14 Ring may vary in range and severity from case to case.  However, in many individuals with the disorder, such abnormalities may include growth delays before and after birth (prenatal and postnatal growth retardation), diminished muscle tone (hypotonia), feeding difficulties during infancy, psychomotor delays, and mental retardation.  In addition, recurrent seizures (epilepsy) typically develop beginning during infancy or early childhood.  The specific form a seizure takes and its associated symptoms may vary, depending upon the region(s) of the brain affected and other factors.  For example, seizure episodes may be characterized by shock-like contractions of certain muscles or muscle groups (myoclonic seizures); increased stiffness (rigidity) and rapid, rhythmic contraction and relaxation of certain muscle groups (tonic-clonic seizures); sensory or behavioral disturbances; lost consciousness; and/or impaired control of certain voluntary functions, such as bowel or bladder control.  (For more information, please choose epilepsy as your search term in the Rare Disease Database.)

Chromosome 14 Ring results from loss (deletion) of genetic material from both ends of the 14th chromosome and joining of the ends to form a ring.  Associated symptoms and findings may vary, depending upon the amount of genetic material lost from the 14th chromosome or the stability of the ring chromosome during subsequent cellular divisions (i.e., mitosis).  Evidence suggests that features associated with Chromosome 14 Ring may result from relatively small deletions of genetic material from the long arm (q) of chromosome 14 (14q).

Chromosome 14 Ring is an extremely rare chromosomal disorder that has appeared to affect males slightly more often than females.  There have been over 40 cases reported in the medical literature.

Additional chromosomal disorders may have features similar to those associated with Chromosome 14 Ring.  Chromosomal testing is necessary to confirm the specific chromosomal abnormality present.  (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use chromosome as your search term in the Rare Disease Database.)

In some cases, a diagnosis of Chromosome 14 Ring may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). Ultrasound studies may reveal characteristic findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Chromosome 14 Ring.


Chromosome 14, Trisomy Mosaic

Chromosome 14, Trisomy Mosaic is a rare chromosomal disorder in which chromosome 14 appears three times (trisomy) rather than twice in some cells of the body. The term mosaic indicates that some cells contain the extra chromosome 14, whereas others have the normal chromosomal pair.

The symptoms and physical findings associated with Chromosome 14, Trisomy Mosaic may depend on the percentage of cells containing the extra 14th chromosome. However, the syndrome is typically characterized by growth and developmental delays, mental retardation, distinctive craniofacial malformations, and/or other physical abnormalities.

In individuals with Chromosome 14, Trisomy Mosaic, chromosome 14 is present three times (trisomy) rather than twice in some cells of the body (mosaicism).  Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p, a long arm identified by the letter q, and a narrowed region at which the two arms are joined (centromere).

In observed cases, Chromosome 14, Trisomy Mosaic has appeared to affect females more frequently than males. Since the chromosomal syndrome was originally described in the medical literature, over 20 cases have been reported.

Other chromosomal disorders may be characterized by symptoms and findings similar to those potentially associated with Chromosome 14, Trisomy Mosaic.  Chromosomal testing is necessary to confirm the specific chromosomal abnormality present.  (For further information on such chromosomal disorders, choose the name of the specific disorder in question or use chromosome as your search term in the Rare Disease Database.)

A diagnosis of Chromosome 14, Trisomy Mosaic may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves are used to create an image of the developing fetus. Ultrasonography may reveal characteristic findings that suggest Chromosome 14, Trisomy Mosaic, such as excessive fluid in the membranous sac surrounding the developing fetus (polyhydramnios), growth retardation, and/or certain physical malformations (e.g., cleft palate). During amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, whereas CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on the fluid or tissue samples may reveal the presence of Chromosome 14, Trisomy Mosaic.


Chromosome 15 Ring

Chromosome 15 Ring results from loss (deletion) of genetic material from both ends of the 15th chromosome and a joining of the ends to form a ring. Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p and a long arm identified by the letter q. Chromosomes are further subdivided into bands that are numbered.

Although associated features may be variable, Chromosome 15 Ring is commonly characterized by growth delays before and after birth, resulting in short stature (dwarfism); varying degrees of mental retardation; low muscle tone (hypotonia); craniofacial malformations; and limb abnormalities.

Chromosome 15 Ring results from loss (deletion) of genetic material from both ends of the 15th chromosome and a joining of the ends to form a ring.  Chromosomes are found in the nucleus of all body cells except red blood cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.

Since Chromosome 15 Ring was originally described, at least 25 cases have been recorded in the medical literature.  In such observed cases, females appear to be affected more frequently than males.

Symptoms of the following disorders may be similar to those of Chromosome 15 Ring.  Comparisons may be useful for a differential diagnosis:

Russell-Silver syndrome (RSS) is a rare genetic disorder characterized by growth delays before and after birth, leading to short stature (dwarfism); overgrowth of one side of the body (hemihypertrophy) that may affect the head, trunk, arms, and/or legs; distinctive craniofacial features; and other physical abnormalities.  Characteristic craniofacial malformations may include a triangular-shaped face with a small, pointed chin; a prominent forehead (frontal bossing); bluish discoloration of the whites of the eyes (blue sclera); an unusually small, wide mouth with downwardly turned corners; and/or a small jaw (micrognathia).  In some cases, additional physical abnormalities may include abnormal deviation or incurving (clinodactyly) of the fifth fingers; webbing or fusion (syndactyly) of certain toes; underdevelopment (hypoplasia) of bones of the fingers (phalanges); coffee-colored patches on the skin (cafe-au-lait spots); and/or abnormalities of the kidneys and urinary tract.  In addition, although most affected individuals have normal intelligence, mild mental retardation may sometimes be present.  In most cases, RSS is thought to result from new genetic changes (mutations) that occur randomly for unknown reasons (sporadically).  Less commonly, it appears that the disorder may be inherited as an autosomal recessive trait.  In addition, a rare form of RSS has been identified that is thought to be inherited as an X-linked dominant trait.


Chromosome 15, Distal Trisomy 15q

15号染色体长臂远端三体

Chromosome 15, Distal Trisomy 15q is an extremely rare chromosomal disorder in which the end (distal) portion of the long arm (q) of the 15th chromosome (15q) appears three times (trisomy) rather than twice in cells of the body. The disorder is characterized by growth delays before and/or after birth (prenatal and/or postnatal growth retardation); mental retardation; and/or distinctive malformations of the head and facial (craniofacial) area. Additional abnormalities typically include an unusually short neck; malformations of the fingers and/or toes; abnormal sideways curvature of the spine (scoliosis) and/or other skeletal malformations; genital abnormalities, particularly in affected males; and/or, in some cases, heart (cardiac) defects. The range and severity of symptoms and physical findings may vary from case to case, depending upon the length and location of the duplicated portion of chromosome 15q. In most cases, Chromosome 15, Distal Trisomy 15q is due to a chromosomal balanced translocation in one of the parents.

In individuals with Chromosome 15, Distal Trisomy 15q, an extremely rare chromosomal disorder, the end (distal) portion of the long arm (q) of chromosome 15 (15q) is duplicated (trisomic).  Symptoms and physical characteristics associated with the disorder may vary in range and severity, depending upon the exact size and location of the duplicated portion of chromosome 15q.

Chromosome 15, Distal Trisomy 15q is an extremely rare chromosomal disorder in which the end (distal) portion of the long arm (q) of the 15th chromosome appears three times (trisomy) rather than twice in cells of the body. Chromosomes are found in the nucleus of all body cells except red blood cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p and a long arm identified by the letter q. Chromosomes are further subdivided into bands that are numbered.  For example, 15q21 refers to band 21 on the long arm of chromosome 15.

Chromosome 15, Distal Trisomy 15q is an extremely rare chromosomal disorder that is thought to affect males approximately twice as often as females.  Since the disorder was originally described in the medical literature in 1974 (A. Fujimoto), more than 30 cases have been reported in the literature.  The majority of symptoms and physical features associated with the disorder are apparent at birth.

Other chromosomal disorders may be characterized by prenatal and postnatal growth retardation, mental retardation, distinctive craniofacial abnormalities, genital malformations, congenital heart defects, and/or other abnormalities similar to those potentially associated with Chromosome 15, Distal Trisomy 15q. Chromosomal testing is necessary to confirm the specific chromosomal abnormality present.  (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use chromosome as your search term in the Rare Disease Database.)

In some cases, the diagnosis of Chromosome 15, Distal Trisomy 15q may be determined before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS. Ultrasound studies may reveal characteristic findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During amniocentesis, a sample of fluid that surrounds the developing fetus is removed and studied. During chorionic villus sampling, a tissue sample is removed from a portion of the placenta. Chromosomal studies performed on this fluid or tissue sample may reveal the presence of Distal Trisomy 15q.


Chromosome 18 Ring

Chromosome 18 Ring is a rare disorder in which there is loss (deletion) of genetic material from one or both ends of the 18th chromosome and joining of the chromosomal ends to form a ring.  Associated symptoms and findings may vary greatly in range and severity from case to case, depending upon the amount and location of lost genetic material and other factors. A ring may also be formed without the loss of any genetic material. However, many individuals with the disorder are affected by mental retardation; low muscle tone (hypotonia); growth retardation; repeated infections during the first years of life; and/or malformations of the skull and facial (craniofacial) region. Such craniofacial features often include an unusually small head (microcephaly), widely spaced eyes (ocular hypertelorism), and/or vertical skin folds that cover the eyes’ inner corners (epicanthal folds). Chromosome 18 Ring is usually caused by spontaneous (de novo) errors very early in the development of the embryo that appear to occur randomly for unknown reasons (sporadically).

As mentioned above, associated symptoms and physical features may be extremely variable.   For example, there have been a few cases in which individuals with Chromosome 18 Ring have few or no apparent symptoms.  However, others with the chromosomal abnormality may have multiple, severe features of the disorder.  In most affected individuals, characteristic features include moderate to severe mental retardation; growth delays; poor muscle tone (hypotonia); craniofacial malformations; eye abnormalities; and/or an increased susceptibility to certain infections.

Chromosome 18 Ring results from loss (deletion) of genetic material from one or both ends of the 18th chromosome and a joining of the ends to form a ring.  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.

Since Chromosome 18 Ring was originally described, more than 70 cases have been reported in the medical literature.  In these observed cases, females appear to be affected slightly more often than males.  The disorder is often detected at birth or during prenatal testing.

Symptoms of the following disorders may be similar to those of Chromosome 18 Ring.  Comparisons may be useful for a differential diagnosis:

Ultrasound will indicate that something unusual is happening to the fetus. The diagnosis of Chromosome 18 Ring is made before birth (prenatally) by specialized tests such as amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During fetal blood sampling, blood is drawn with a needle that is guided via ultrasound into the umbilical vein. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta.  Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Chromosome 18 Ring.


Chromosome 18, Monosomy 18p

Chromosome 18, Monosomy 18p is a rare chromosomal disorder in which all or part of the short arm (p) of chromosome 18 is deleted (monosomic). The disorder is typically characterized by short stature, variable degrees of mental retardation, speech delays, malformations of the skull and facial (craniofacial) region, and/or additional physical abnormalities. Associated craniofacial defects may vary greatly in range and severity from case to case. However, such features commonly include an unusually small head (microcephaly); a broad, flat nose; a carp-shaped mouth; large, protruding ears; widely spaced eyes (ocular hypertelorism); and/or other abnormalities. Rarely (i.e., in about 10 percent of cases), Monosomy 18p may be associated with holoprosencephaly, a condition in which the forebrain (prosencephalon) fails to divide properly during embryonic development. Holoprosencephaly may result in varying degrees of mental retardation, other neurologic findings, and/or extremely variable midline facial defects, such as the presence of a single, central front tooth (maxillary incisor); closely spaced eyes (hypotelorism); an abnormal groove in the upper lip (cleft lip); incomplete closure of the roof of the mouth (cleft palate); and/or, in severe cases, absence of the nose and/or cyclopia. Cyclopia is characterized by fusion of the eye cavities (orbits) into a single cavity containing one eye.

The symptoms and physical findings associated with Chromosome 18, Monosomy 18p may be variable from case to case.  However, the syndrome is typically characterized by short stature, mental retardation, various malformations of the skull and facial (craniofacial) region, and/or additional physical abnormalities.

Chromosome 18, Monosomy 18p is a chromosomal abnormality in which there is deletion (monosomy) of all or a portion of the short arm (p) of chromosome 18.  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.

Chromosome 18, Monosomy 18p appears to affect females more frequently than males by a ratio of approximately three to two.  Reports indicate that the mean parental age is older than average for the mothers and fathers of children with Monosomy 18p (i.e., age 32 years and 38 years, respectively).  Since Monosomy 18p was originally described in 1963, over 120 cases have been reported in the medical literature.

Symptoms of the following disorders may be similar to those of Chromosome 18, Monosomy 18p.  Comparisons may be useful for a differential diagnosis:

In some cases, Chromosome 18, Monosomy 18p may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain findings that suggest a chromosomal disorder or other developmental abnormalities. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta.  Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Monosomy 18p.


Chromosome 18, Tetrasomy 18p

Chromosome 18, Tetrasomy 18p is a very rare chromosomal disorder in which the short arm of the 18th chromosome (18p) appears four times (tetrasomy) rather than twice in cells of the body. Individuals with a normal chromosomal make-up (karyotype) have two 18th chromosomes, both of which have a short arm (18p) and a long arm (18q). However, in individuals with Chromosome 18, Tetrasomy 18p, four short arms (18ps) are present in cells of the body rather than the normal two.

Chromosome 18, Tetrasomy 18p is a very rare chromosomal disorder in which the short arm of chromosome 18 (18p) appears four times (tetrasomy) rather than twice in cells of the body.  Symptoms may vary from case to case.

Chromosome 18, Tetrasomy 18p is a rare chromosomal disorder in which the short arm of chromosome 18 (18p) appears four times (tetrasomy) rather than twice in cells of the body. Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.

Chromosome 18, Tetrasomy 18p is a very rare chromosomal disorder that appears to affect males and females equally.  Approximately 40 cases have been reported in the medical literature.

Symptoms of the following disorders may be similar to those of Chromosome 18, Tetrasomy 18p. Comparisons may be useful for a differential diagnosis:

The diagnosis of Chromosome 18, Tetrasomy 18p may be determined before birth (prenatally) by specialized tests such as ultrasound, fetal blood sampling, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves are used to create an image of the developing fetus. Ultrasound studies may reveal characteristic findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During fetal blood sampling, blood is drawn with a needle that is guided via ultrasound into the umbilical vein. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on fluid or tissue samples (i.e., obtained via fetal blood sampling, amniocentesis, or CVS) may reveal the presence of Chromosome 18p Tetrasomy.


Chromosome 18q- Syndrome

Chromosome 18q- syndrome (also known as Chromosome 18, Monosomy 18q) is a rare chromosomal disorder in which there is deletion of part of the long arm (q) of chromosome 18. Associated symptoms and findings may vary greatly in range and severity from case to case. However, characteristic features include short stature; mental retardation; poor muscle tone (hypotonia); malformations of the hands and feet; and abnormalities of the skull and facial (craniofacial) region, such as a small head (microcephaly), a carp-shaped mouth, deeply set eyes, prominent ears, and/or unusually flat, underdeveloped midfacial regions (midfacial hypoplasia). Some affected individuals may also have visual abnormalities, hearing impairment, genital malformations, structural heart defects, and/or other physical abnormalities. Chromosome 18q- syndrome usually appears to result from spontaneous (de novo) errors very early during embryonic development that occur for unknown reasons (sporadically).

As noted above, associated symptoms and findings may vary from case to case.  However, many infants with the disorder have a low birth weight and growth delays after birth, resulting in short stature.  In addition, Chromosome 18q- syndrome is often characterized by low muscle tone (hypotonia); sudden episodes of uncontrolled electrical activity in the brain (seizures); moderate to severe delays in the acquisition of skills requiring the coordination of mental and physical activities (psychomotor retardation); and varying degrees of mental retardation.  Evidence suggests that most individuals with the disorder are affected by profound, severe, or moderate mental retardation.  However, mild mental deficiency has been reported in some cases.  In addition, some affected children may have behavioral problems, such as abnormally increased activity (hyperactivity), aggressive behavior, and tantrums.

Chromosome 18q- syndrome is a chromosomal disorder in which there is deletion (monosomy) of part of the long arm (q) of chromosome 18.  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.  For example, 18q21 refers to band 21 of the long arm of chromosome 18.

Chromosome 18q- syndrome appears to affect females more frequently than males by a ratio of approximately three to two.  Since the disorder was originally reported in the medical literature in 1964, more than 80 cases have been recorded.

Symptoms of the following disorders may be similar to those of Chromosome 18q- syndrome.  Comparisons may be useful for a differential diagnosis:

In some cases, Chromosome 18q- syndrome may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain findings that suggest a chromosomal disorder or other developmental abnormalities. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Monosomy 18q.


Chromosome 21 Ring

Chromosome 21 Ring is a rare chromosomal disorder in which the affected infant has a breakage of chromosome 21 at both ends, and the ends of the chromosome join together to form a ring. The amount of genetic material lost at the two ends of the chromosome may vary. As a result, an infant with very little absent genetic material may have no apparent symptoms while an infant with a significant part of the chromosomal ends missing may have many symptoms. When symptoms of the disorder are present, the affected infant may have mental retardation as well as abnormalities of the face, eyes, skeleton, and/or internal organs.

The symptoms and findings associated with Chromosome 21 Ring may be extremely variable, depending upon the amount and location of genetic material lost from the 21st chromosome and other factors.  As a result, some individuals with Chromosome 21 Ring may have few or no associated symptoms, whereas others may have severe physical abnormalities and mental retardation.

Chromosome 21 Ring results from loss (deletion) of genetic material from both ends of the 21st chromosome and joining of the ends to form a ring.  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.

Chromosome 21 Ring is a rare chromosomal disorder that appears to affect males and females in equal numbers.

Symptoms of the following disorders may be similar to those of Chromosome 21 Ring. Comparisons may be useful for a differential diagnosis:

Down Syndrome is a chromosomal disorder in which all or a portion of chromosome 21 appears three times (trisomy) rather than twice in cells of the body.  Associated symptoms may vary greatly, depending on the length and location of the duplicated (trisomic) portion of chromosome 21 as well as the percentage of cells containing the abnormality.  However, many affected infants may have low muscle tone (hypotonia), a poor startle (Moro) reflex, excessive flexibility of the joints, and distinctive malformations of the head and facial (craniofacial) area.  Craniofacial abnormalities may include a short, small head (microbrachycephaly); upwardly slanting eyelid folds (palpebral fissures); a small nose with a depressed nasal bridge; a relatively flat facial profile; and excessive skin on the back of the neck.  Down Syndrome may also be characterized by abnormalities of the extremities, short stature, mental retardation, hearing impairment, and/or structural malformations of the heart.   In addition, those with the disorder may have an increased susceptibility to respiratory disease (e.g., pneumonia), other infectious diseases, and malignancies in which there is an increased proliferation of certain white blood cells (leukemia).  (For further information, use Down or trisomy 21 as your search term in the Rare Disease Database.)


Chromosome 22 Ring

Ring chromosome 22 is a rare genetic condition that occurs when one chromosome 22 forms a circular or ring, structure. The ring forms after loss (deletion) of genetic material from both the short arm and long arm of chromosome 22. The size of the deletion is variable, ranging from less than 100kb to greater than 10Mb. The clinical features are also variable but typically include developmental delay, poor muscle tone (hypotonia), severe speech delay and minor physical features such as large ears and bulbous nose. The ring chromosome typically occurs de novo, meaning that it is a new event in the child and was not inherited. Chromosome studies and genetic counseling are indicated for parents of a child with a ring chromosome to determine if the ring was inherited and to provide important information about what the ring will mean for the development and medical care of their child.  People with ring 22 are at risk of developing neurofibromatosis type 2 (NF2). Treatment is directed to the specific signs and symptoms that the affected person has.

The first indication that a child has ring chromosome 22 may be poor muscle tone (hypotonia). An infant may have trouble feeding, holding their head up and staying in a sitting position. As the child grows, other motor milestones such as crawling and walking will be delayed and the child may exhibit poor coordination, lack of balance and an unsteady gait. Moderate to profound intellectual disability is common, as is severely delayed or absent speech. Autism or autistic-like behavior is frequently seen. Mood disorders and other behavioral issues including aggression and hyperactivity have also been described.

Ring chromosome 22 is formed when genetic material is lost (deleted) from both ends of chromosome 22 and the broken ends fuse to form a circular chromosome or ring. Chromosomes typically are rod-like structures that are found in the nucleus of our body cells. They are composed of genetic material (DNA) and proteins, and their function is to transmit genetic information from generation to generation. The normal chromosome number is 46, or 23 pairs of chromosomes, with one member of each pair inherited from the mother and the other from the father. The chromosomes numbered from 1 to 22, according to length from longest to shortest, are called autosomes. The remaining pair of chromosomes are the sex chromosomes which are XX in females and XY in males.

Ring chromosome 22 is a rare genetic condition with over 60 cases in the medical literature since 1968. Males and females are equally likely to be affected.

Phelan-McDermid syndrome (PMS) is a rare genetic disorder resulting from a deletion of the distal long arm of chromosome 22 or from a pathogenic variant of the SHANK3 gene located at 22q13. PMS is characterized by mild to profound intellectual impairment, motor delay, absent to severely delayed speech, neonatal hypotonia, autism or autistic-like features and mild physical features.

There are two common methods used when a chromosome disorder is suspected. One is chromosomal microarray (CMA) and the other is next-generation sequencing (NGS). These are called molecular genetic tests because they diagnose conditions at the level of the DNA molecule. Two techniques are sometimes used to confirm the results of CMA and NGS. One is FISH (fluorescence in situ hybridization) which is a targeted method to determine if a segment of DNA is present or absent. FISH can be performed on uncultured cells or on chromosomes derived from cultured cells. The other technique is chromosome analysis which relies on counting the number of chromosomes in a subset of cells and examining chromosome structure to determine if an abnormality is present. Chromosome analysis (sometimes called karyotyping) is the only method that permits visualization of the ring chromosome at the microscope.

Therapies should be designed to address the needs of each individual. Early intervention programs are available for babies and young children with developmental delays. These may include physical therapy, occupational therapy, speech therapy and other therapies as the child develops. Behavior therapies may be more intense in children with autism or autistic-like features. Adaptive sports, such as swimming and horseback riding, may help improve muscle tone, coordination and balance.


Chromosome 22q11.2 Deletion Syndrome

22q11.2远端微缺失综合征

Disorders with more than one identifying feature are called syndromes. 22q11.2DS has numerous features associated with it, not all of which will be present in every affected individual.

Individuals with 22q11.2DS are missing a small part of chromosome 22. The deletion occurs at a specific location on the long arm (q arm) of chromosome 22 (region 22q11) and often includes a deletion of genes in the DiGeorge chromosomal region (DGCR). The majority of individuals (85%) have a common, standard-size deletion of approximately 3 megabases (Mb). However, 15% of individuals with 22q11.2DS have a deletion of a smaller size, often referred to as nested or distal deletions. These individuals present with nearly the same spectrum of findings as those individuals with the standard deletion.

The prevalence of 22q11.2DS has been estimated to be approximately 1/3000 to 1/6,000 live births. These numbers may well be higher due to the variability of the condition, difficulty in properly diagnosing, and lack of newborn screening.

Symptoms of the following disorders can be similar to those of 22q11.2DS. Comparisons may be useful for a differential diagnosis:

Smith-Lemli-Opitz syndrome (SLOS) is a variable genetic disorder that is characterized by slow growth before and after birth, small head (microcephaly), mild to moderate intellectual disability and multiple birth defects including cleft palate, heart defects, fused second and third toes, extra fingers and toes and underdeveloped external genitals in males. The severity of SLOS varies greatly in affected individuals, even in the same family, and some have normal development and only minor birth defects. SLOS is caused by a deficiency in the enzyme 7-dehydrocholesterol reductase that results in an abnormality in cholesterol metabolism. SLOS is inherited as an autosomal recessive genetic disorder. (For more information on this disorder choose SLOS as your search term in the Rare Disease Database.)


Chromosome 3, Monosomy 3p

Chromosome 3, Monosomy 3p is a rare chromosomal disorder in which the end (distal) portion of the short arm (p) of chromosome 3 is missing (deleted or monosomic). The range and severity of symptoms and findings may be variable. However, associated features often include growth delays before and after birth (prenatal and postnatal growth deficiency); severe to profound mental retardation; distinctive malformations of the skull and facial (craniofacial) region; eyebrows that grow together (synophrys); and/or excessive hair growth (hypertrichosis). Additional physical abnormalities may also be present. In many cases, Chromosome 3, Monosomy 3p appears to occur spontaneously (de novo) for unknown reasons.

As noted above, the symptoms and physical findings associated with Chromosome 3, Monosomy 3p may vary in range and severity from case to case.  However, according to reports in the medical literature, many affected individuals have a low birthweight; marked growth delays after birth (postnatal growth retardation); severe to profound mental retardation; severe delays in the acquisition of skills requiring the coordination of mental and motor activities (psychomotor retardation); excessive hair growth (hypertrichosis); and/or distinctive malformations of the skull and facial (craniofacial) region.

Chromosome 3, Monosomy 3p is a rare chromosomal disorder in which there is deletion (monosomy) of the end (distal) portion of the short arm (p) of chromosome 3.  Researchers indicate that symptoms and findings characteristic of the syndrome result from deletion of chromosomal material extending from band 25 on the short arm of chromosome 3 (breakpoint) to the end or terminal of 3p (3p25–>pter).  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.  Therefore, 3p25 refers to band 25 on the short arm of chromosome 3.

Chromosome 3, Monosomy 3p appears to affect males and females in relatively equal numbers.  Since the disorder was originally reported in 1978 (Verjaal M), approximately 34 cases have been described in the medical literature.

Additional chromosomal disorders may have features similar to those associated with Chromosome 3, Monosomy 3p.  Chromosomal analysis is necessary to confirm the specific chromosomal abnormality present.  (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use chromosome as your search term in the Rare Disease Database.)

In some cases, Chromosome 3, Monosomy 3p may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta.  Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Monosomy 3p.


Chromosome 3, Trisomy 3q2

染色体3q29微重复综合征

Chromosome 3, Trisomy 3q2 is a rare chromosomal disorder in which a portion of the 3rd chromosome appears three times (trisomy) rather than twice in cells of the body. Associated symptoms and findings may be variable, depending upon the specific length and location of the duplicated (trisomic) portion of chromosome 3. However, many affected infants and children have developmental delays, mental retardation, and characteristic abnormalities of the head and facial (craniofacial) area, resulting in a distinctive facial appearance. Such craniofacial abnormalities may include a relatively short head (brachycephaly), widely spaced eyes (ocular hypertelorism), upwardly slanting eyelid folds (palpebral fissures), and a small nose with upturned nostrils (anteverted nares). Affected infants and children also tend to have long eyelashes; arched, bushy, well-defined eyebrows that grow together across the base of the nose (synophrys), an unusually low hairline on the forehead and the back of the neck; and generalized excessive hair growth (hirsutism). Chromosome 3, Trisomy 3q2 may also be characterized by eye (ocular) abnormalities, limb defects, structural heart malformations (congenital heart defects), or other physical features.

The symptoms and physical findings associated with Chromosome 3, Trisomy 3q2 may be variable.  However, in many cases, the disorder is characterized by mental retardation, moderate to severe developmental delays, abnormally diminished muscle tone (hypotonia), distinctive abnormalities of the head and facial (craniofacial) area, and/or additional physical abnormalities.  According to reports in the medical literature, craniofacial features and other physical abnormalities associated with Trisomy 3q2 are often very similar to those associated with a rare genetic disorder known as Cornelia de Lange syndrome.  (For further information on Cornelia de Lange syndrome, please see the Related Disorders section of this report below.)

In individuals with Chromosome 3, Trisomy 3q2, all or a portion of the end (distal) region of the long arm (q) of chromosome 3 is present three times (trisomy) rather than twice in cells of the body.  (This distal region is sometimes referred to as chromosome 3q2.)  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into bands that are numbered.  For example, 3q26 refers to band 26 within the distal region of the long arm of chromosome 3.

Chromosome 3, Trisomy 3q2 appears to affect males and females in equal numbers. At least 50 cases have been reported in the medical literature.  In some cases, the disorder may be suspected before birth (prenatally) based upon the results of specialized tests.  (For further information, please see the Standard Therapies section of this report below.)  The disorder is usually detected or confirmed at birth or during early infancy based upon characteristic symptoms and physical findings.

Symptoms of the following disorders may be similar to those of Chromosome 3, Trisomy 3q2. Comparisons may be useful for a differential diagnosis.

In some cases, a diagnosis of Chromosome 3, Trisomy 3q2 may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves are used to create an image of the developing fetus. Ultrasound studies may reveal characteristic findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed. CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on cells from the fluid or tissue samples may reveal the presence of Trisomy 3q2.


Chromosome 4, Partial Trisomy Distal 4q

Chromosome 4, Partial Trisomy 4q (4q21-qter to 4q32-qter, included)

Chromosome 4, Partial Trisomy Distal 4q is a rare chromosomal disorder in which a portion of the fourth chromosome appears three times (trisomy) rather than twice in cells of the body. Associated symptoms and findings may vary from case to case. However, common features include growth deficiency; mental retardation; distinctive malformations of the skull and facial (craniofacial) region, including an unusually small head (microcephaly), malformed ears, and a prominent nasal bridge; and/or defects of the hands and feet. In some cases, additional physical abnormalities may also be present, such as structural defects of the heart that are present at birth (congenital heart defects); genital abnormalities in affected males; urinary tract defects; and/or other findings. In most cases, the trisomy appears to result from a balanced chromosomal rearrangement in one of the parents; rarely, it is thought to arise from spontaneous (de novo) errors very early in embryonic development that occur for unknown reasons (sporadically).

Chromosome 4, Partial Trisomy Distal 4q is commonly characterized by a low birth weight and growth deficiency.  In addition, many affected infants have low muscle tone (hypotonia), with unusual floppiness of voluntary (skeletal) muscles, or excessive muscle tone (hypertonia), with increased resistance to passive stretching.  Additional characteristic features include mental retardation and delays in the acquisition of skills that require the coordination of mental and motor activities (psychomotor retardation).

In individuals with Chromosome 4, Partial Trisomy Distal 4q, an end (distal) region of the long arm (q) of the fourth chromosome appears three times (trisomy) rather than twice in cells of the body.  Distal indicates away or farthest from a particular point of reference, meaning the chromosome’s centromere (described below).

In observed cases, Chromosome 4, Partial Trisomy Distal 4q has appeared to affect males and females in relatively equal numbers. More than 60 cases have been reported in the medical literature.

Symptoms of the following disorders may be similar to those of Chromosome 4, Partial Trisomy Distal 4q. Comparisons may be useful for a differential diagnosis:

Chromosome 4, Trisomy 4p is a rare chromosomal disorder in which all or a portion of the short arm (p) of chromosome 4 appears three times rather than twice in cells of the body.  Associated symptoms and findings may vary in range and severity from case to case.  However, features commonly include growth deficiency, severe mental retardation, psychomotor retardation, and characteristic craniofacial malformations.  Such craniofacial defects may include an abnormally small head (microcephaly); large, malformed ears; a bulbous nose; widely spaced eyes (ocular hypertelorism); a prominent chin; a short neck; and/or other findings.  The disorder may also be characterized by skeletal, genital, cardiac, renal, and/or additional physical abnormalities.  In many cases, Chromosome 4, Partial Trisomy 4p is due to a balanced chromosomal rearrangement in one of the parents. Other cases have appeared to result from spontaneous (de novo) errors early in embryonic development. (For more information on this disorder, choose Trisomy 4p as your search term in the Rare Disease Database.)


Chromosome 4, Trisomy 4p

Chromosome 4, Trisomy 4p is a rare chromosomal disorder in which all or a portion of the short arm (p) of chromosome 4 appears three times (trisomy) rather than twice in cells of the body. Associated symptoms and physical findings may vary greatly in range and severity from case to case. Such variability may depend upon the specific length and location of the duplicated (trisomic) portion of chromosome 4p as well as other factors. However, many affected infants may have feeding and breathing difficulties, characteristic malformations of the head and facial (craniofacial) area, and abnormalities of the hands and feet. Additional features may include other skeletal defects, genital abnormalities in affected males, or heart (cardiac) defects. Trisomy 4p is also characterized by severe mental retardation.

The symptoms and physical findings associated with Chromosome 4, Trisomy 4p may be variable.  However, in many cases, the disorder is characterized by growth deficiency before and after birth (prenatal and postnatal growth retardation); feeding problems during early infancy; and increased muscle tone (hypertonia) in the first months of life, followed by diminished muscle tone (hypotonia).  Affected infants may also have respiratory difficulties, potentially leading to life-threatening complications.

In individuals with Chromosome 4, Trisomy 4p, all or a portion of the short arm (p) of chromosome 4 appears three times (trisomy) rather than twice in cells of the body. Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p, a long arm identified by the letter q, and a narrowed region at which the two arms are joined (centromere).  Chromosomes are further subdivided into bands that are numbered outward from the centromere.  For example, the short arm of chromosome 4 includes bands 4p11 to 4p16; the latter, which is the end or terminal band of 4p, is also known as 4pter.

Chromosome 4, Trisomy 4p appears to affect males and females in relatively equal numbers.  Trisomy for the short arm of chromosome 4 was originally described in 1970 (Wilson MG) and delineated as a distinct clinical syndrome in 1977 (Gonzalez CH).  More than 85 patients with the syndrome have been reported in the medical literature.

Many chromosomal disorders may have features similar to those associated with Chromosome 4, Trisomy 4p.  Chromosomal testing is necessary to confirm the specific chromosomal abnormality present.  (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use chromosome as your search term in the Rare Disease Database.)

In some cases, a diagnosis of Trisomy 4p may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves are used to create an image of the developing fetus. Ultrasound studies may reveal characteristic findings that suggest a chromosomal disorder or other developmental abnormalities in the fetus. During amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, whereas CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on the fluid or tissue samples may reveal the presence of Trisomy 4p.


Chromosome 4q Deletion

染色体4q21微缺失综合征

Patients with chromosome 4q deletion may have the following symptoms: unusual skull shape, short nose with unusual bridge, low-set ears that may not have formed well, cleft in the roof of the mouth, short breastbone, poor or delayed growth, moderate to severe intellectual disability, heart defects, unusual heart rhythm (arrhythmia), defective urinary and reproductive organs (genitourinary defects), small size, small hands and feet, unusually wide-set eyes (hypertelorism), a pointed fifth finger and nail which is common for this disorder, and decreased muscle tone (hypotonia). Some children may have a small jaw (micrognathia) which results in difficulties with breathing. There may be unusual brain findings (corpus callosum). In some patients, slow growth and intellectual disability may be present without obvious physical abnormalities, making it difficult to recognize this disorder.

Genetic information, DNA, lies within almost every cell in the body and provides the instructions for how each tissue functions. DNA includes genes, which are responsible for making the proteins that have specific jobs within certain tissues of the body. This DNA is tightly wound and contained within structures called chromosomes. Most people are born with 23 pairs (46 total) of chromosomes in every cell of the body. Each of these 46 chromosomes has a long piece, called arm q, and a short piece, called arm p. Chromosome 4q deletion is caused by a partial missing piece of the long arm of chromosome 4. This chromosome deletion is usually not inherited, but occurs for the first time in the affected person. However, it is possible to pass the deletion to children.

Chromosome 4q deletion is a rare disorder that is present at birth and is estimated to occur in 1 out of 100,000 people. Chromosome 4q deletion can sometimes be identified before birth by ultrasound and prenatal chromosome analysis. The condition affects males and females in equal numbers. It is not currently known to affect certain ethnicities more than others. There is typically no family history of the condition, and it occurs randomly.

Other chromosomal disorders may be similar to chromosome 4q deletion. Comparisons may be useful for a differential diagnosis:

Wolf-Hirschorn syndrome (4p-syndrome) is a chromosomal disorder caused by a partial deletion of part of the short arm of chromosome 4. Major symptoms include very wide-set eyes (ocular hypertelorism) with a broad or beaked nose, a small head (microcephaly), low-set malformed ears, mental and growth deficiency, heart (cardiac) defects, and seizures. (For more information on this disorder, choose Wolf-Hirschorn as your search term in the Rare Disease Database.)


Chromosome 5, Trisomy 5p

chromosome 5, trisomy 5p, complete (5p11-ter), included

Trisomy 5p is a rare chromosomal disorder in which all or a portion of the short arm (p) of chromosome 5 (5p) appears three times (trisomy) rather than twice in cells of the body. Often the duplicated portion of 5p (trisomy) is due to a complex rearrangement involving other chromosomes. These individuals have a variable phenotype depending on which chromosome is involved, the size of the duplication and whether there is loss of material from the same or another chromosome.

The symptoms and physical findings associated with trisomy 5p are variable and depend on the location and size of the duplicated segment.  The information reported here is from case reports with duplications, markers, rings or translocations involving the short arm of chromosome 5 with the short arm of an acrocentric chromosome (13,14,15,21,or 22).  Other findings may be present if there are monosomies (deletions) due to complex rearrangements or translocations involving other chromosomes and the short arm of chromosome 5p.

In individuals with trisomy 5p, all or a portion of the short arm (p) of chromosome 5 (5p) appears three times (trisomy) rather than twice in cells of the body. Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p, a long arm identified by the letter q, and a narrowed region at which the two arms are joined (centromere). Chromosomes are further subdivided into bands that are numbered outward from the centromere. For example, the short arm of chromosome 5 includes bands 5p10 (at the centromere or constriction of the chromosome) to 5p15, which is the end of the short arm or terminal band of 5p (also known as 5pter).

In observed cases, trisomy 5p has appeared to affect females slightly more often than males and affects all ethnic groups. More than 40 cases have been described since the original description by Lejeune in 1964.

While the features for trisomy 5p appear consistent, the diagnosis cannot be made on clinical features alone. Many of the features seen in trisomy 5p can be seen in other genetic conditions or chromosomal abnormalities. (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use chromosome as your search term in the Rare Disease Database.)

A blood chromosome (cytogenetic) study or a chromosomal microarray analysis is required to make the diagnosis.


Chromosome 6 Ring

Chromosome 6 Ring is a rare disorder in which there is loss (deletion) of chromosomal material from both ends of the 6th chromosome and joining of the ends to form a ring.  Associated symptoms and findings may vary greatly, depending upon the amount and location of lost chromosomal material and other factors. For example, there have been some reported cases in which children with Chromosome 6 Ring have few physical abnormalities and normal intelligence. However, many with the chromosomal abnormality are affected by growth retardation; varying degrees of mental retardation; mild to severe delays in the acquisition of skills requiring the coordination of mental and physical activities (psychomotor retardation); and/or various abnormalities of the skull and facial (craniofacial) region. Such craniofacial features often include an unusually small head (microcephaly), malformed or low-set ears, and/or a small jaw (micrognathia). Eye (ocular) defects are also relatively common, such as drooping of the upper eyelids (ptosis), unusually small eyes (microphthalmia), abnormal deviation of one eye in relation to the other (strabismus), and/or other findings. Chromosome 6 Ring usually appears to result from spontaneous (de novo) errors very early in the development of the embryo that occur for unknown reasons (sporadically).

As noted above, associated symptoms and physical features may vary greatly in range and severity.  Some cases have been reported in which children with Chromosome 6 Ring have normal intelligence and minimal physical abnormalities.  However, others with the chromosomal abnormality may be affected by multiple characteristic features of the disorder.  Such features frequently include growth retardation before and after birth (prenatal and postnatal growth retardation) and associated short stature; poor muscle tone (hypotonia), psychomotor delays, and mild to profound mental retardation; craniofacial malformations; and/or ocular defects.  In some cases, additional physical abnormalities may also be present.

Chromosome 6 Ring results from deletion (monosomy) of chromosomal material from the long arm (q) and short arm (p) of chromosome 6 and a joining of the ends to form a ring.  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p, a long arm identified by the letter q, and a narrowed region at which the two arms are joined (centromere).  Chromosomes are further subdivided into bands that are numbered.

Since Chromosome 6 Ring was originally described, approximately 23 cases have been reported in the medical literature.  In observed cases, males appear to be affected slightly more frequently than females.

Symptoms of the following disorders may be similar to those of Chromosome 6 Ring.  Comparisons may be useful for a differential diagnosis:

In some cases, Chromosome 6 Ring may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain findings that suggest a chromosomal disorder or other abnormalities. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta.  Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Chromosome 6 Ring.


Chromosome 6, Partial Trisomy 6q

Chromosome 6, Partial Trisomy 6q is an extremely rare chromosomal disorder in which a portion of the 6th chromosome (6q) is present three times (trisomy) rather than twice in cells of the body. Associated symptoms and findings may vary in range and severity from case to case. However, many affected infants and children have slow physical development (growth retardation); mental retardation; malformations of the skull and facial (craniofacial) region; an unusually short, webbed neck; abnormal bending (flexion) or extension of certain joints in fixed postures (joint contractures); and/or other physical abnormalities. In most cases, Chromosome 6, Partial Trisomy 6q has been the result of a balanced translocation in one of the parents.

As noted above, the symptoms and physical findings associated with Chromosome 6, Trisomy 6q may be variable.  However, in many cases, the disorder is characterized by growth delays before and after birth, severe to profound mental retardation, a delay in the acquisition of skills requiring coordination of muscular and mental activity (psychomotor retardation), distinctive malformations of the skull and facial (craniofacial) region, musculoskeletal abnormalities, and/or additional physical features.

In individuals with Chromosome 6, Partial Trisomy 6q, all or a portion of the end (distal) region of the long arm (q) of chromosome 6 is present three times (trisomy) rather than twice in cells of the body.  Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p and a long arm identified by the letter q.  Chromosomes are further subdivided into regions and bands that are numbered.  For example, the distal region of the long arm of chromosome 6, which is referred to as 6q2, includes bands 6q21 to 6q27.

Chromosome 6, Partial Trisomy 6q is an extremely rare chromosomal disorder that appears to affect males and females equally.  Approximately 30 cases have been reported in the medical literature.

Additional chromosomal disorders may have features similar to those potentially associated with Chromosome 6, Partial Trisomy 6q.  Chromosomal testing is necessary to confirm the specific chromosomal abnormality present.  (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use chromosome as your search term in the Rare Disease Database.)

In some cases, Chromosome 6, Partial Trisomy 6q may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain findings that suggest a chromosomal disorder or other abnormalities. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal studies performed on such fluid or tissue samples may reveal the presence o. Partial Trisomy 6q.


Chromosome 7, Partial Monosomy 7p

Chromosome 7, 7p Deletion Syndrome, Partial

Chromosome 7, Partial Monosomy 7p is a rare chromosomal disorder characterized by deletion (monosomy) of a portion of the short arm (p) of chromosome 7 (7p). Associated symptoms and findings may be variable and may depend on the specific size and location of the deleted segment of 7p. However, in many cases, there is early closure of the fibrous joints (cranial sutures) between certain bones of the skull (craniosynostosis), resulting in an abnormally shaped head. For example, depending on the specific sutures involved, the forehead may appear unusually triangular shaped (trigonocephaly) or the head may seem abnormally long and narrow with the top pointed or conical (turricephaly). Affected infants and children may also have additional malformations of the skull and facial (craniofacial) region. Such abnormalities may include an unusually small head (microcephaly), closely or widely set eyes (ocular hypotelorism or hypertelorism), downslanting eyelid folds (palpebral fissures), and/or other findings.

As noted above, the symptoms and physical findings associated with Chromosome 7, Partial Monosomy 7p may vary in range and severity from case to case.  However, many affected individuals have growth delays before and after birth (prenatal and postnatal growth retardation).  The syndrome may also be associated with varying degrees of psychomotor retardation and mental retardation; however, as noted earlier, some affected individuals may have normal intelligence.

In individuals with Chromosome 7, Partial Monosomy 7p, there is deletion (monosomy) of a portion of the short arm (p) of chromosome 7. Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p, a long arm identified by the letter q, and a narrowed region at which the two arms are joined (centromere).  Chromosomes are further subdivided into bands that are numbered outward from the centromere.  For example, the short arm of chromosome 7 (7p) includes bands 7p11-p15 and bands 7p21-p22; the end or terminal of 7p is known as 7pter.

Chromosome 7, Partial Monosomy 7p is a rare chromosomal disorder that appears to affect males and females in relatively equal numbers.  More than 30 cases have been reported in the medical literature.

Additional chromosomal disorders may be characterized by symptoms and findings similar to those associated with Chromosome 7, Partial Monosomy 7p.  Chromosomal testing is necessary to confirm the specific chromosomal abnormality present.  (For further information on such disorders, choose the name of the specific chromosomal disorder in question or use chromosome as your search term in the Rare Disease Database.)

In some cases, the diagnosis of Chromosome 7, Partial Monosomy 7p may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain characteristic findings that suggest a chromosomal disorder or other abnormalities. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Partial Monosomy 7p.


Chromosome 8, Monosomy 8p

Chromosome 8, Monosomy 8p is a rare chromosomal disorder characterized by deletion (monosomy) of a portion of the eighth chromosome. Associated symptoms and findings may vary greatly in range and severity from case to case. However, common features include growth deficiency; mental retardation; malformations of the skull and facial (craniofacial) region, such as a small head (microcephaly) and vertical skin folds that may cover the eyes’ inner corners (epicanthal folds); heart (cardiac) abnormalities; and/or genital defects in affected males. Additional craniofacial features may also be present that tend to become less apparent with age, such as a short, broad nose; a low, wide nasal bridge; and/or a small jaw (micrognathia). In most cases, Chromosome 8, Monosomy 8p appears to result from spontaneous (de novo) errors very early in embryonic development that occur for unknown reasons.

As noted above, associated features may be extremely variable.  However, in many cases, there are growth delays during fetal development (intrauterine growth retardation) as well as after birth (postnatal growth retardation).

In cases of Chromosome 8, Monosomy 8p, there is deletion (monosomy) of an end (distal) portion of the short arm (p) of chromosome  8.  Distal indicates away or farthest from a particular point of reference, meaning the chromosome’s centromere (described below).

Chromosome 8, Monosomy 8p appears to affect males and  females in relatively equal numbers.  Since the disorder was originally described in 1973, over 20 cases have  been reported in the medical literature.

Symptoms of the following disorders may be similar to those of Chromosome 8,  Monosomy 8p.  Comparisons may be useful for a differential diagnosis:

In some instances, the diagnosis of Chromosome 8, Monosomy 8p may be suggested before birth (prenatally) by specialized tests such as ultrasound, amniocentesis, and/or chorionic villus sampling (CVS). During fetal ultrasonography, reflected sound waves create an image of the developing fetus, potentially revealing certain characteristic findings that suggest a chromosomal disorder or other abnormalities. With amniocentesis, a sample of fluid that surrounds the developing fetus is removed and analyzed, while CVS involves the removal of tissue samples from a portion of the placenta. Chromosomal analysis performed on such fluid or tissue samples may reveal the presence of Monosomy 8p2.


Chromosome 9 Ring

Chromosome 9 Ring is a rare disorder in which there is loss (deletion) of chromosomal material from both ends of the 9th chromosome and joining of the ends to form a ring. Associated symptoms and findings may vary, depending upon the amount and location of lost chromosomal material and other factors. Some affected individuals may have variable malformations of the skull and facial (craniofacial) region. However, in others with the chromosomal abnormality, such features may not be apparent. Chromosome 9 Ring may also be characterized by additional physical features in some cases, including growth retardation, heart defects, genital abnormalities, and/or other findings. In addition, many affected individuals have moderate to severe intellectual disability; however, in some instances, intelligence may be in the low normal range. Chromosome 9 Ring usually appears to result from spontaneous (de novo) errors very early in the development of the embryo that occur for unknown reasons (sporadically).

As noted above, Chromosome 9 Ring may be characterized by various craniofacial malformations; however, in some cases, such features may not be apparent.  Craniofacial defects associated with Chromosome 9 Ring may include an abnormally small head (microcephaly) and/or premature fusion of the fibrous joint (suture) between bones forming the forehead (metopic suture), resulting in an unusually narrow, pointed, triangular or keel-shaped forehead (trigonocephaly) and closely spaced eyes (ocular hypotelorism).  Some affected individuals may also have abnormally slanting eyelid folds (palpebral fissures), slight protrusion of the eyes (exophthalmos), an exaggerated arch to the eyebrows, a small jaw (micrognathia) and small chin, and/or a short neck.

Chromosome 9 Ring is caused by deletion of chromosomal material from the end (distal) regions of the short arm (p) and long arm (q) of chromosome 9 and joining of the ends to form a ring.  Chromosomes are found in the nucleus of all body cells.  They carry the genetic characteristics of each individual.  Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females.  Each chromosome has a short arm designated as p, a long arm identified by the letter q and a narrowed region at which the two arms are joined (centromere).  Chromosomes are further subdivided into bands that are numbered outward from the centromere.

Chromosome 9 Ring is a rare chromosomal abnormality that is thought to affect males and females in relatively equal numbers.  Since the disorder was originally described, more than 12 cases have been reported in the medical literature.

Symptoms of the following disorders may be similar to those of Chromosome 9 Ring. Comparisons may be useful for a differential diagnosis:

Chromosome 9, Partial Monosomy 9p is a chromosomal disorder characterized by deletion (monosomy) of part of the end (distal) region of the short arm (p) of chromosome 9 (i.e., with the breakpoint usually located within band 9p22).  Characteristic features include variable degrees of intellectual disability; craniofacial, limb, heart (cardiac), and/or genital abnormalities; and/or other physical malformations.  Common craniofacial defects include a triangular- or keel-shaped forehead (trigonocephaly); a short nose, flattened nasal bridge, and upturned nostrils (anteverted nares); prominent eyes; upwardly slanting eyelid folds (palpebral fissures); vertical skin folds that may cover the eyes’ inner corners (epicanthal folds); highly arched eyebrows; a small jaw (micrognathia); a short, broad neck; and/or other features.  In most cases, Partial Monosomy 9p appears to result from spontaneous (de novo) errors very early during embryonic development.  (For further information, choose Monosomy 9p as your search term in the Rare Disease Database.)


Chromosome 9, Partial Monosomy 9p

9号染色体短臂远端单倍体

Chromosome 9, Partial Monosomy 9p is a rare chromosomal disorder in which there is deletion (monosomy) of a portion of the 9th chromosome. Characteristic symptoms and findings include intellectual disability; distinctive malformations of the skull and facial (craniofacial) region, such as an abnormally shaped forehead (i.e., trigonocephaly), upwardly slanting eyelid folds (palpebral fissures), and unusually flat midfacial regions (midfacial hypoplasia); structural malformations of the heart (congenital heart defects); genital defects in affected males and females; and/or additional physical abnormalities. In most cases, Chromosome 9, Partial Monosomy 9p appears to result from spontaneous (de novo) errors very early in embryonic development that occur for unknown reasons (sporadically).

Most infants with Chromosome 9, Partial Monosomy 9p have a normal birth weight and length.  However, the disorder is typically characterized by variable delays in the acquisition of skills requiring the coordination of mental and physical activities (psychomotor delay) and moderate or mild intellectual disability.  Reports indicate that affected individuals tend to have an affectionate, friendly, and sociable personality.

In individuals with Chromosome 9, Partial Monosomy 9p, there is deletion (monosomy) of part of the end (distal) region of the short arm (p) of chromosome 9.  (Distal indicates away or farthest from a particular point of reference, meaning the chromosome’s centromere [described below].)  Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as p, a long arm identified by the letter q, and a narrowed region at which the two arms are joined (centromere).  Chromosomes are further subdivided into bands that are numbered outward from the centromere.  For example, 9p22 refers to band 22 of the short arm of chromosome 9.

In observed cases, Chromosome 9, Partial Monosomy 9p has appeared to affect females more frequently than males.  Since the disorder was originally described, more than 100 cases have been reported in the medical literature.

Symptoms of the following disorders may be similar to those of Chromosome 9, Partial Monosomy 9p. Comparisons may be useful for a differential diagnosis:

Chromosome 9 Ring is a rare chromosomal disorder in which there is loss (deletion) of genetic material from the end (distal) regions of the short arm and long arm of the 9th chromosome and joining of the ends to form a ring.  Associated symptoms and findings may vary, depending upon the amount and location of lost chromosomal material and other factors.  Some affected individuals may have variable craniofacial malformations; however, in others with the chromosomal abnormality, such features may not be apparent.  Craniofacial defects associated with Chromosome 9 Ring may include an abnormally small head (microcephaly); a triangular- or keel-shaped forehead (trigonocephaly); abnormally slanting eyelid folds (palpebral fissures); slight protrusion of the eyes (exophthalmos); a small jaw (micrognathia); and/or a short neck.  In some cases, additional physical features may include growth delay after birth, congenital heart defects, genital abnormalities, and/or other findings.  In addition, many affected individuals have moderate to severe intellectual disability; however, in some instances, intelligence may be in the low normal range.  Chromosome 9 Ring usually appears to result from spontaneous (de novo) errors very early during embryonic development.  (For further information on this disorder, choose Chromosome 9 Ring as your search term in the Rare Disease Database.)


特发性慢性嗜酸细胞性肺炎

Idiopathic chronic eosinophilic pneumonia

Symptoms of CEP are general and nonspecific. The disorder is chronic and slowly progressive with symptoms usually developing insidiously over weeks or months. Breathing (respiratory) difficulties are always present in some form and can include progressive shortness of breath (dyspnea) and a nonproductive cough. Dyspnea can range from mild to severe. Wheezing occurs in approximately 50% of individuals. Some individuals may cough up a mixture of saliva and mucus (sputum).

CEP is caused by the abnormal accumulation of eosinophils in lung tissue and the bloodstream. Normally, eosinophils only account for approximately 5% of circulating white blood cells in healthy individuals. Researchers believe that CEP may develop due to an unidentified, nonspecific triggering agent that causes the body to produce eosinophils. The exact reason for the overproduction and accumulation of eosinophils is unknown.

CEP is a rare disorder, but the exact prevalence is unknown. The disorder can occur in individuals of any age, but is extremely rare in childhood. The peak incidence is during the fifth decade. CEP occurs twice as often in women than men.

Symptoms of the following disorders can be similar to those of CEP. Comparisons may be useful for a differential diagnosis.

A diagnosis of CEP is based upon identification of characteristic symptoms (e.g., eosinophilic pneumonia), a detailed patient history, a thorough clinical evaluation, the absence of other known causes of eosinophilic lung disease, and a variety of specialized tests. A physical examination may reveal low levels of oxygen in the blood (hypoxemia), a rapid heart rate (tachycardia), wheezes and a rattling sound in the lungs (rales).


Chronic granulomatous disease

Chronic granulomatous disease (CGD) is a rare inherited primary immune deficiency disorder that affects certain white blood cells (neutrophils, monocytes, macrophages, eosinophils). The disorder is characterized by an inability to resist infections caused by certain types of bacterial and fungal species and a tendency to develop chronic inflammation. Life-threatening recurrent fungal and bacterial infections affecting the skin, lungs, liver and bones may occur. In addition, patients can develop swollen areas of inflamed tissues known as granulomas that can be widely distributed, as well as other inflammatory conditions, including those involving the gastrointestinal tract.  Symptoms usually begin in infancy or childhood. Individuals with mild forms of the disorder may not develop symptoms until the teens or adulthood. Chronic granulomatous disease is a genetic disorder caused by changes (variants or mutations) in genes responsible for producing an important enzyme in white blood cells. Certain white blood cells use this enzyme to produce hydrogen peroxide that these cells need to kill certain bacteria and fungi and to properly regulate white blood cell responses to inflammation. These oxidants also regulate white blood cell pathways involved in the immune response and inflammation even in the absence of infection. Thus, patients with CGD have problems with both infections and increased inflammation.

Chronic granulomatous disease is characterized by a susceptibility to repeated bacterial and fungal infections. CGD can also be associated with the development of granulomatous lesions of the skin, lungs, bones and lymph nodes formed by collections of inflammatory white blood cells. Excess gamma globulin in the blood (hypergammaglobulinemia), low levels of circulating red blood cells (anemia), an increase in white blood cells (leukocytosis) can occur as a result of repeated infections or chronic inflammation. Evidence of chronic infections may be seen in the liver, gastrointestinal tract, brain and eyes.

Chronic granulomatous disease is a genetic disease. Changes (variants or mutations) in any one of five different genes can cause a defect in an enzyme called phagocyte NADPH oxidase. Certain white blood cells use this enzyme to produce hydrogen peroxide, which these cells need to kill certain bacteria and fungi and to properly regulate white blood cell responses to inflammation.

Chronic granulomatous disease affects males more often than females. In North American and European studies, approximately, two-thirds of individuals have the X-linked recessive form of the disorder. Symptoms from CGD usually first occur during infancy or childhood, but sometimes may be delayed until the early teens. In a few cases, the first symptoms have been known to occur in adulthood.

Symptoms of the following disorders can be similar to those of chronic granulomatous disease. Comparisons may be useful for a differential diagnosis:

Granulomatosis with polyangiitis is an uncommon collagen vascular disorder (also referred to as connective tissue disorder) affecting the blood vessels. This is a type of autoimmune disorder that begins as a localized inflammation of the upper and lower respiratory tract mucous membranes, and usually progresses into generalized inflammation of the blood vessels (vasculitis) and kidney (glomerulonephritis). Initial symptoms usually appear as a severe cold progressing to sinusitis, ulcerations of the mucous membranes in the nose with secondary bacterial infection, middle ear infection (otitis media), cough, expectoration of blood (hemoptysis) and pleuritis. The nasal mucous membrane appears red with a raised granular appearance. There may also be fever, loss of appetite and generalized discomfort. (For more information on this disorder, choose granulomatosis with polyangiitis as your search term in the Rare Disease Database.)


慢性炎症性脱髓鞘性多发性神经病

Chronic inflammatory demyelinating polyneuropathy

Chronic Inflammatory Demyelinating Polyneuropathy

The chief symptoms of CIDP are slowly progressive (over at least 2 months) symmetric weakness of both muscles around the hip and shoulder as well as of the hands and feet (both proximal and distal muscles). This pattern of weakness, if caused by nerve damage, is highly suggestive of CIDP. Nerve signals become altered causing impairment in motor function and/or abnormal, or loss of, sensation. There are usually some alterations of sensation causing incoordination, numbness, tingling, or prickling sensations. Some patients only have sensory symptoms and signs but have the typical abnormalities of nerve conduction and respond to treatment as in CIDP in which weakness predominates. This is considered a sensory variant of CIDP.

The exact cause of CIDP is unknown but there are strong indications that CIDP is an autoimmune disorder. Autoimmune disorders occur when the body’s natural defenses (antibodies and lymphocytes) against invading organisms suddenly begin to attack perfectly healthy tissue. The cause of autoimmune disorders is unknown. Recent studies have detected antibodies directed against constituents of peripheral nerve (neurofascin 155 and contactin 1) that cause rare variants of CIDP. These findings provide encouragement that the cause of other forms of CIDP will be recognized.

CIDP is a rare disorder that can affect any age group and the onset of the disorder may begin during any decade of life. CIDP affects males twice as often as females and the average age of onset is 50. The prevalence of CIDP is estimated to be around 5-7 cases per 100,000 individuals.

Symptoms of the following disorders can be similar to those of CIDP. Comparisons may be useful for a differential diagnosis:

Multifocal motor neuropathy (MMN) is a rare disorder characterized by asymmetric or multifocal weakness of the arms and legs without sensory signs or symptoms. MMN usually affects one side of the body more than the other (asymmetric) and affects the arms more often than the legs. Degeneration (atrophy) of the muscles of the arms and legs is also often present. The disorder is usually slowly progressive over several years. The exact cause of MMN is unknown. (For more information on this disorder choose multifocal motor neuropathy as your search term in the Rare Disease Database.)


Chronic Intestinal Pseudo-Obstruction

The specific symptoms and severity of CIP can vary greatly from one person to another, depending, in part, on the exact location and extent of the disease within the gastrointestinal tract. Any area of the GI tract can potentially be affected, but the small bowel is most commonly affected. By definition, CIP is chronic in nature and individuals usually have continuous symptoms of bowel obstruction. However, affected individuals may also experience recurrent episodes or acute attacks during which time symptoms worsen and become more pronounced. In between such episodes, affected individuals may experience vague, nonspecific symptoms relating to the GI tract and bowel obstruction. In extremely rare cases, some affected individuals do not have symptoms in between such attacks.

CIP is generally broken down into primary CIP, in which there is an intrinsic defect affecting the muscles or nerves that control the passage of food and other material through the GI tract, and secondary CIP, in which the disorder results from another, underlying non-gastrointestinal disorder or condition. In many cases the cause of CIP is unknown; these cases may be categorized as idiopathic and are sometimes referred to as chronic idiopathic intestinal pseudo-obstruction (CIIP).

CIP affects males and females in equal numbers and can affect individuals of any age. The prevalence of CIP in the general population is unknown. According to some sources approximately 100 new cases of CIP are reported in children in the United States each year. However, CIP often goes unrecognized or misdiagnosed making it extremely difficult to determine the true frequency of CIP in the general population. Children are predominantly affected by primary, non-familial, sporadic CIP. Adults are generally affected by secondary CIP, most often due to systemic diseases such as scleroderma, diabetes, or paraneoplastic syndromes.

Symptoms of the following disorders can be similar to those of CIP. Comparisons may be useful for a differential diagnosis.

A diagnosis of CIP is made based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and a variety of specialized tests to rule out other conditions or identify underlying causes. Symptoms of CIP should be present for at least six months before a diagnosis of CIP can be made.


B-cell chronic lymphocytic leukemia

B细胞慢性淋巴细胞白血病

Chronic lymphocytic leukemia (CLL) is a malignant blood disorder in which there are an increased number of white blood cells in the lymphoid tissue. In CLL, the abnormal lymphocytes, also called leukemic cells, are produced instead of healthy white blood cells, and then accumulate over time. As the number of unhealthy blood cells grows, there is less room for healthy cells. The combination of fewer healthy cells and the fact that the CLL lymphocytes are poor at fighting infections can lead to frequent infection, anemia, and easy bleeding. This disease progresses slowly, and the uncontrolled buildup and enlargement of lymphoid tissue can occur in various sites of the body such as the lymph nodes, spleen, bone marrow, and lungs. CLL is the most common type of leukemia in adults and very rarely occurs in children. In the majority of individuals, chronic lymphocytic leukemia is the result of a rapid production of B lymphocyte cells (a type of white blood cell that is responsible for the production of antibodies to help fight infection). What was previously called CLL derived from T lymphocytes has been renamed as another disorder, T cell prolymphocytic leukemia. The overgrowth of cells in this T-cell disease tends to be much faster. The ability to distinguish between cells that have unmutated IgVH (Ig-unmutated CLL) and mutated IgVH (Ig-mutated CLL) has become very important in predicting the course of the disease (prognosis). Patients who have Ig-unmutated CLL have a much shorter time to treatment and historically a shorter average survival period compared to Ig-mutated CLL patients, whose average survival period exceeded 25 years even before the advent of modern therapy. These survival times however are based on much older data and are certainly longer now, with improved therapies. The other major determinant of prognosis is the chromosome makeup of the CLL, with particular concern about two higher risk chromosome abnormalities, loss of the short arm of chromosome 17 or the long arm of chromosome 11Determining the subset of CLL based on IGVH status is important because it is very predictive of prognosis. Because CLL usually progresses so slowly, many patients do not need immediate treatment and some do not even require it in their lifetime. Treatment is still based primarily on symptoms or worsening blood counts, not on these prognostic factors.

Approximately 50-75% of patients with chronic lymphocytic leukemia have no symptoms when first diagnosed. The disease is discovered during a routine exam or blood test. Symptoms can be similar between the two subdivisions of CLL, Ig-mutated and Ig-unmutated, although when Ig-unmutated CLL progresses, typically sooner, more symptoms may ensue.

The exact cause of chronic lymphocytic leukemia is not known. Multiple genetic mutations occur in the DNA of blood-producing cells. These mutations cause the blood cells to produce abnormal lymphocytes, which are not effective at fighting infection.

Chronic lymphocytic leukemia is the most common type of leukemia found in multiple family members. It is twice as common in males as in females and the average age of onset in patients is 72. It is also more common in people that are white, or of Russian and Eastern European Jewish heritage. The rate of incidence of the disorder increases with age. CLL almost never affects children and is rare under the age of thirty. In the United States, it is thought that three out of every 100,000 people will develop CLL, but this may be an underestimate.

Symptoms of the following disorders can be similar to those of chronic lymphocytic leukemia. Comparisons may be useful for a differential diagnosis.

CLL is most commonly discovered when an abnormally high white blood cell count is noticed in routine blood work. A diagnosis can be made with one of the following tests:


Congenital generalized lipodystrophy

Many individuals with CML show nonspecific symptoms at the time of diagnosis. The most common symptoms are fatigue, weakness, itchiness, night sweats, abdominal discomfort, and weight loss. An abnormally enlarged spleen (splenomegaly) is usually discovered upon physical examination. CML is commonly diagnosed when an affected individual is undergoing blood tests for a different reason. Sometimes, no symptoms are present at all.

The exact cause of CML is not known. Blood samples of patients with CML show the presence of abnormal cells that reproduce more rapidly than normal cells. Ninety percent of these neoplastic cells show a consistent rearrangement of chromosomes. This rearrangement is the result of a transfer of genetic material from chromosome 22 to chromosome 9 and vice versa. As a result of this transference, chromosome 22 ends up shorter than normal. This shortened chromosome is known as the Philadelphia chromosome, and is present in the blood cells of 90% of people with CML. Formation of the Philadelphia chromosome results in a fused gene, called BCR-ABL. This gene contains instructions that make the disease blood cells produce far too much of a protein called tyrosine kinase. This protein causes the cancer by allowing the diseased blood cells to grow out of control.

CML is slightly more prevalent in males than in females. It may occur at any age, but predominantly affects people in their 40s and 50s. There are more than 4,000 new cases of the 30,000 new cases of leukemia, diagnosed each year. There is an increased incidence rate of CML among people who have been exposed to radiation, such as the survivors of the atomic bombs dropped in Nagasaki and Hiroshima.

Symptoms of the following disorders can be similar to those of chronic myelogenous leukemia. Comparisons may be useful for a differential diagnosis:

Polycythemia vera is a rare chronic myeloproliferative disorder characterized by overproduction of red blood cells and elements of the bone marrow involved in the formation of red blood cells (hematopoietic elements). In most cases, affected individuals may experience headaches, weakness, dizziness (vertigo), and/or a ringing noise in the ear (tinnitus). In some cases, individuals with polycythemia vera experience itching (pruritis), especially after a hot bath. Affected individuals often have an abnormally enlarged spleen (splenomegaly) and/or liver (hepatomegaly). In some cases, affected individuals may have associated conditions including high blood pressure (hypertension), the formation of blood clots (thrombosis), and/or rupturing of and loss of blood (hemorrhaging) from certain blood vessels. The exact cause of polycythemia vera is not known. (For more information on this disorder, choose polcythemia vera as your search term in the Rare Disease Database.)