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genetic changes | What are the genetic changes related to Clouston syndrome ? | Clouston syndrome is caused by mutations in the GJB6 gene. This gene provides instructions for making a protein called gap junction beta 6, more commonly known as connexin 30. Connexin 30 is a member of the connexin protein family. Connexin proteins form channels called gap junctions, which permit the transport of nutrients, charged atoms (ions), and signaling molecules between neighboring cells. The size of the gap junction and the types of particles that move through it are determined by the particular connexin proteins that make up the channel. Gap junctions made with connexin 30 transport potassium ions and certain small molecules. Connexin 30 is found in several different tissues throughout the body, including the skin (especially on the palms of the hands and soles of the feet), hair follicles, and nail beds, and plays a role in the growth and development of these tissues. GJB6 gene mutations that cause Clouston syndrome change single protein building blocks (amino acids) in the connexin 30 protein. Although the effects of these mutations are not fully understood, they lead to abnormalities in the growth, division, and maturation of cells in the hair follicles, nails, and skin. |
inheritance | Is Clouston syndrome inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family. |
treatment | What are the treatments for Clouston syndrome ? | These resources address the diagnosis or management of Clouston syndrome: - Gene Review: Gene Review: Hidrotic Ectodermal Dysplasia 2 - Genetic Testing Registry: Hidrotic ectodermal dysplasia syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) familial hypertrophic cardiomyopathy ? | Familial hypertrophic cardiomyopathy is a heart condition characterized by thickening (hypertrophy) of the heart (cardiac) muscle. Thickening usually occurs in the interventricular septum, which is the muscular wall that separates the lower left chamber of the heart (the left ventricle) from the lower right chamber (the right ventricle). In some people, thickening of the interventricular septum impedes the flow of oxygen-rich blood from the heart, which may lead to an abnormal heart sound during a heartbeat (heart murmur) and other signs and symptoms of the condition. Other affected individuals do not have physical obstruction of blood flow, but the pumping of blood is less efficient, which can also lead to symptoms of the condition. Cardiac hypertrophy often begins in adolescence or young adulthood, although it can develop at any time throughout life. The symptoms of familial hypertrophic cardiomyopathy are variable, even within the same family. Many affected individuals have no symptoms. Other people with familial hypertrophic cardiomyopathy may experience chest pain; shortness of breath, especially with physical exertion; a sensation of fluttering or pounding in the chest (palpitations); lightheadedness; dizziness; and fainting. While most people with familial hypertrophic cardiomyopathy are symptom-free or have only mild symptoms, this condition can have serious consequences. It can cause abnormal heart rhythms (arrhythmias) that may be life threatening. People with familial hypertrophic cardiomyopathy have an increased risk of sudden death, even if they have no other symptoms of the condition. A small number of affected individuals develop potentially fatal heart failure, which may require heart transplantation. |
frequency | How many people are affected by familial hypertrophic cardiomyopathy ? | Familial hypertrophic cardiomyopathy affects an estimated 1 in 500 people worldwide. It is the most common genetic heart disease in the United States. |
genetic changes | What are the genetic changes related to familial hypertrophic cardiomyopathy ? | Mutations in one of several genes can cause familial hypertrophic cardiomyopathy; the most commonly involved genes are MYH7, MYBPC3, TNNT2, and TNNI3. Other genes, including some that have not been identified, may also be involved in this condition. The proteins produced from the genes associated with familial hypertrophic cardiomyopathy play important roles in contraction of the heart muscle by forming muscle cell structures called sarcomeres. Sarcomeres, which are the basic units of muscle contraction, are made up of thick and thin protein filaments. The overlapping thick and thin filaments attach to each other and release, which allows the filaments to move relative to one another so that muscles can contract. In the heart, regular contractions of cardiac muscle pump blood to the rest of the body. The protein produced from the MYH7 gene, called cardiac beta ()-myosin heavy chain, is the major component of the thick filament in sarcomeres. The protein produced from the MYBPC3 gene, cardiac myosin binding protein C, associates with the thick filament, providing structural support and helping to regulate muscle contractions. The TNNT2 and TNNI3 genes provide instructions for making cardiac troponin T and cardiac troponin I, respectively, which are two of the three proteins that make up the troponin protein complex found in cardiac muscle cells. The troponin complex associates with the thin filament of sarcomeres. It controls muscle contraction and relaxation by regulating the interaction of the thick and thin filaments. It is unknown how mutations in sarcomere-related genes lead to hypertrophy of the heart muscle and problems with heart rhythm. The mutations may result in an altered sarcomere protein or reduce the amount of the protein. An abnormality in or shortage of any one of these proteins may impair the function of the sarcomere, disrupting normal cardiac muscle contraction. Research shows that, in affected individuals, contraction and relaxation of the heart muscle is abnormal, even before hypertrophy develops. However, it is not clear how these contraction problems are related to hypertrophy or the symptoms of familial hypertrophic cardiomyopathy. |
inheritance | Is familial hypertrophic cardiomyopathy inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Rarely, both copies of the gene are altered, leading to more severe signs and symptoms. In most cases, an affected person has one parent with the condition. |
treatment | What are the treatments for familial hypertrophic cardiomyopathy ? | These resources address the diagnosis or management of familial hypertrophic cardiomyopathy: - Cleveland Clinic - Gene Review: Gene Review: Hypertrophic Cardiomyopathy Overview - Genetic Testing Registry: Familial hypertrophic cardiomyopathy 1 - Genetic Testing Registry: Familial hypertrophic cardiomyopathy 2 - Genetic Testing Registry: Familial hypertrophic cardiomyopathy 4 - Genetic Testing Registry: Familial hypertrophic cardiomyopathy 7 - MedlinePlus Encyclopedia: Hypertrophic Cardiomyopathy - Stanford University Hospitals and Clinics - The Sarcomeric Human Cardiomyopathies Registry (ShaRe) These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) keratitis-ichthyosis-deafness syndrome ? | Keratitis-ichthyosis-deafness (KID) syndrome is characterized by eye problems, skin abnormalities, and hearing loss. People with KID syndrome usually have keratitis, which is inflammation of the front surface of the eye (the cornea). The keratitis may cause pain, increased sensitivity to light (photophobia), abnormal blood vessel growth over the cornea (neovascularization), and scarring. Over time, affected individuals experience a loss of sharp vision (reduced visual acuity); in severe cases the keratitis can lead to blindness. Most people with KID syndrome have thick, hard skin on the palms of the hands and soles of the feet (palmoplantar keratoderma). Affected individuals also have thick, reddened patches of skin (erythrokeratoderma) that are dry and scaly (ichthyosis). These dry patches can occur anywhere on the body, although they most commonly affect the neck, groin, and armpits. Breaks in the skin often occur and may lead to infections. In severe cases these infections can be life-threatening, especially in infancy. Approximately 12 percent of people with KID syndrome develop a type of skin cancer called squamous cell carcinoma, which may also affect mucous membranes such as the lining of the mouth. Partial hair loss is a common feature of KID syndrome, and often affects the eyebrows and eyelashes. Affected individuals may also have small, abnormally formed nails. Hearing loss in this condition is usually profound, but occasionally is less severe. |
frequency | How many people are affected by keratitis-ichthyosis-deafness syndrome ? | KID syndrome is a rare disorder. Its prevalence is unknown. Approximately 100 cases have been reported. |
genetic changes | What are the genetic changes related to keratitis-ichthyosis-deafness syndrome ? | KID syndrome is caused by mutations in the GJB2 gene. This gene provides instructions for making a protein called gap junction beta 2, more commonly known as connexin 26. Connexin 26 is a member of the connexin protein family. Connexin proteins form channels called gap junctions that permit the transport of nutrients, charged atoms (ions), and signaling molecules between neighboring cells that are in contact with each other. Gap junctions made with connexin 26 transport potassium ions and certain small molecules. Connexin 26 is found in cells throughout the body, including the inner ear and the skin. In the inner ear, channels made from connexin 26 are found in a snail-shaped structure called the cochlea. These channels may help to maintain the proper level of potassium ions required for the conversion of sound waves to electrical nerve impulses. This conversion is essential for normal hearing. In addition, connexin 26 may be involved in the maturation of certain cells in the cochlea. Connexin 26 also plays a role in the growth and maturation of the outermost layer of skin (the epidermis). The GJB2 gene mutations that cause KID syndrome change single protein building blocks (amino acids) in connexin 26. The mutations are thought to result in channels that constantly leak ions, which impairs the health of the cells and increases cell death. Death of cells in the skin and the inner ear may underlie the ichthyosis and deafness that occur in KID syndrome. It is unclear how GJB2 gene mutations affect the eye. Because at least one of the GJB2 gene mutations identified in people with KID syndrome also occurs in hystrix-like ichthyosis with deafness (HID), a disorder with similar features but without keratitis, many researchers categorize KID syndrome and HID as a single disorder, which they call KID/HID. It is not known why some people with this mutation have eye problems while others do not. |
inheritance | Is keratitis-ichthyosis-deafness syndrome inherited ? | KID syndrome is usually inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In some cases, an affected person inherits the mutation from one affected parent. However, most cases result from new mutations in the gene and occur in people with no history of the disorder in their family. A few families have had a condition resembling KID syndrome with an autosomal recessive pattern of inheritance. In autosomal recessive inheritance, both copies of a gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. Affected individuals in these families have liver disease, which is not a feature of the autosomal dominant form. The autosomal recessive condition is sometimes called Desmons syndrome. It is unknown whether it is also caused by GJB2 gene mutations. |
treatment | What are the treatments for keratitis-ichthyosis-deafness syndrome ? | These resources address the diagnosis or management of keratitis-ichthyosis-deafness syndrome: - Genetic Testing Registry: Autosomal recessive keratitis-ichthyosis-deafness syndrome - Genetic Testing Registry: Keratitis-ichthyosis-deafness syndrome, autosomal dominant These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) 7q11.23 duplication syndrome ? | 7q11.23 duplication syndrome is a condition that can cause a variety of neurological and behavioral problems as well as other abnormalities. People with 7q11.23 duplication syndrome typically have delayed development of speech and delayed motor skills such as crawling and walking. Speech problems and abnormalities in the way affected individuals walk and stand may persist throughout life. Affected individuals may also have weak muscle tone (hypotonia) and abnormal movements, such as involuntary movements of one side of the body that mirror intentional movements of the other side. Behavioral problems associated with this condition include anxiety disorders (such as social phobias and selective mutism, which is an inability to speak in certain circumstances), attention deficit hyperactivity disorder (ADHD), physical aggression, excessively defiant behavior (oppositional disorder), and autistic behaviors that affect communication and social interaction. While the majority of people with 7q11.23 duplication syndrome have low-average to average intelligence, intellectual development varies widely in this condition, from intellectual disability to, rarely, above-average intelligence. About one-fifth of people with 7q11.23 duplication syndrome experience seizures. About half of individuals with 7q11.23 duplication syndrome have enlargement (dilatation) of the blood vessel that carries blood from the heart to the rest of the body (the aorta); this enlargement can get worse over time. Aortic dilatation can lead to life-threatening complications if the wall of the aorta separates into layers (aortic dissection) or breaks open (ruptures). The characteristic appearance of people with 7q11.23 duplication syndrome can include a large head (macrocephaly) that is flattened in the back (brachycephaly), a broad forehead, straight eyebrows, and deep-set eyes with long eyelashes. The nose may be broad at the tip with the area separating the nostrils attaching lower than usual on the face (low insertion of the columella), resulting in a shortened area between the nose and the upper lip (philtrum). A high arch in the roof of the mouth (high-arched palate) and ear abnormalities may also occur in affected individuals. |
frequency | How many people are affected by 7q11.23 duplication syndrome ? | The prevalence of this disorder is estimated to be 1 in 7,500 to 20,000 people. |
genetic changes | What are the genetic changes related to 7q11.23 duplication syndrome ? | 7q11.23 duplication syndrome results from an extra copy of a region on the long (q) arm of chromosome 7 in each cell. This region is called the Williams-Beuren syndrome critical region (WBSCR) because its deletion causes a different disorder called Williams syndrome, also known as Williams-Beuren syndrome. The region, which is 1.5 to 1.8 million DNA base pairs (Mb) in length, includes 26 to 28 genes. Extra copies of several of the genes in the duplicated region, including the ELN and GTF2I genes, likely contribute to the characteristic features of 7q11.23 duplication syndrome. Researchers suggest that an extra copy of the ELN gene in each cell may be related to the increased risk for aortic dilatation in 7q11.23 duplication syndrome. Studies suggest that an extra copy of the GTF2I gene may be associated with some of the behavioral features of the disorder. However, the specific causes of these features are unclear. Researchers are studying additional genes in the duplicated region, but none have been definitely linked to any of the specific signs or symptoms of 7q11.23 duplication syndrome. |
inheritance | Is 7q11.23 duplication syndrome inherited ? | 7q11.23 duplication syndrome is considered to be an autosomal dominant condition, which means one copy of chromosome 7 with the duplication in each cell is sufficient to cause the disorder. Most cases result from a duplication that occurs during the formation of reproductive cells (eggs and sperm) or in early fetal development. These cases occur in people with no history of the disorder in their family. Less commonly, an affected person inherits the chromosome with a duplicated segment from a parent. |
treatment | What are the treatments for 7q11.23 duplication syndrome ? | These resources address the diagnosis or management of 7q11.23 duplication syndrome: - Cardiff University (United Kingdom): Copy Number Variant Research - Gene Review: Gene Review: 7q11.23 Duplication Syndrome - Genetic Testing Registry: Williams-Beuren region duplication syndrome - University of Antwerp (Belgium): 7q11.23 Research Project - University of Louisville: 7q11.23 Duplication Syndrome Research - University of Toronto: 7q11.23 Duplication Syndrome Research These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) 22q13.3 deletion syndrome ? | 22q13.3 deletion syndrome, which is also commonly known as Phelan-McDermid syndrome, is a disorder caused by the loss of a small piece of chromosome 22. The deletion occurs near the end of the chromosome at a location designated q13.3. The features of 22q13.3 deletion syndrome vary widely and involve many parts of the body. Characteristic signs and symptoms include developmental delay, moderate to profound intellectual disability, decreased muscle tone (hypotonia), and absent or delayed speech. Some people with this condition have autism or autistic-like behavior that affects communication and social interaction, such as poor eye contact, sensitivity to touch, and aggressive behaviors. They may also chew on non-food items such as clothing. Less frequently, people with this condition have seizures. Individuals with 22q13.3 deletion syndrome tend to have a decreased sensitivity to pain. Many also have a reduced ability to sweat, which can lead to a greater risk of overheating and dehydration. Some people with this condition have episodes of frequent vomiting and nausea (cyclic vomiting) and backflow of stomach acids into the esophagus (gastroesophageal reflux). People with 22q13.3 deletion syndrome typically have distinctive facial features, including a long, narrow head; prominent ears; a pointed chin; droopy eyelids (ptosis); and deep-set eyes. Other physical features seen with this condition include large and fleshy hands and/or feet, a fusion of the second and third toes (syndactyly), and small or abnormal toenails. Some affected individuals have rapid (accelerated) growth. |
frequency | How many people are affected by 22q13.3 deletion syndrome ? | At least 500 cases of 22q13.3 deletion syndrome are known. |
genetic changes | What are the genetic changes related to 22q13.3 deletion syndrome ? | 22q13.3 deletion syndrome is caused by a deletion near the end of the long (q) arm of chromosome 22. The signs and symptoms of 22q13.3 deletion syndrome are probably related to the loss of multiple genes in this region. The size of the deletion varies among affected individuals. A ring chromosome 22 can also cause 22q13.3 deletion syndrome. A ring chromosome is a circular structure that occurs when a chromosome breaks in two places, the tips of the chromosome are lost, and the broken ends fuse together. People with ring chromosome 22 have one copy of this abnormal chromosome in some or all of their cells. Researchers believe that several critical genes near the end of the long (q) arm of chromosome 22 are lost when the ring chromosome 22 forms. If one of the chromosome break points is at position 22q13.3, people with ring chromosome 22 have similar signs and symptoms as those with a simple deletion. Researchers are working to identify all of the genes that contribute to the features of 22q13.3 deletion syndrome. They have determined that the loss of a particular gene on chromosome 22, SHANK3, is likely to be responsible for many of the syndrome's characteristic signs (such as developmental delay, intellectual disability, and impaired speech). Additional genes in the deleted region probably contribute to the varied features of 22q13.3 deletion syndrome. |
inheritance | Is 22q13.3 deletion syndrome inherited ? | Most cases of 22q13.3 deletion syndrome are not inherited. The deletion occurs most often as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development. Affected people typically have no history of the disorder in their family, though they can pass the chromosome deletion to their children. When 22q13.3 deletion syndrome is inherited, its inheritance pattern is considered autosomal dominant because a deletion in one copy of chromosome 22 in each cell is sufficient to cause the condition. About 15 to 20 percent of people with 22q13.3 deletion syndrome inherit a chromosome abnormality from an unaffected parent. In these cases, the parent carries a chromosomal rearrangement called a balanced translocation, in which a segment from one chromosome has traded places with a segment from another chromosome, but no genetic material is gained or lost. Balanced translocations usually do not cause any health problems; however, they can become unbalanced as they are passed to the next generation. Children who inherit an unbalanced translocation can have a chromosomal rearrangement with extra or missing genetic material. Individuals with 22q13.3 deletion syndrome who inherit an unbalanced translocation are missing genetic material from the long arm of chromosome 22, which results in the health problems characteristic of this disorder. |
treatment | What are the treatments for 22q13.3 deletion syndrome ? | These resources address the diagnosis or management of 22q13.3 deletion syndrome: - Gene Review: Gene Review: Phelan-McDermid Syndrome - Genetic Testing Registry: 22q13.3 deletion syndrome - MedlinePlus Encyclopedia: Sweating--absent These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) ALG6-congenital disorder of glycosylation ? | ALG6-congenital disorder of glycosylation (ALG6-CDG, also known as congenital disorder of glycosylation type Ic) is an inherited condition that affects many parts of the body. The signs and symptoms of ALG6-CDG vary widely among people with the condition. Individuals with ALG6-CDG typically develop signs and symptoms of the condition during infancy. They may have difficulty gaining weight and growing at the expected rate (failure to thrive). Affected infants often have weak muscle tone (hypotonia) and developmental delay. People with ALG6-CDG may have seizures, problems with coordination and balance (ataxia), or stroke-like episodes that involve an extreme lack of energy (lethargy) and temporary paralysis. They may also develop blood clotting disorders. Some individuals with ALG6-CDG have eye abnormalities including eyes that do not look in the same direction (strabismus) and an eye disorder called retinitis pigmentosa, which causes vision loss. Females with ALG6-CDG have hypergonadotropic hypogonadism, which affects the production of hormones that direct sexual development. As a result, most females with ALG6-CDG do not go through puberty. |
frequency | How many people are affected by ALG6-congenital disorder of glycosylation ? | The prevalence of ALG6-CDG is unknown, but it is thought to be the second most common type of congenital disorder of glycosylation. More than 30 cases of ALG6-CDG have been described in the scientific literature. |
genetic changes | What are the genetic changes related to ALG6-congenital disorder of glycosylation ? | ALG6-CDG is caused by mutations in the ALG6 gene. This gene provides instructions for making an enzyme that is involved in a process called glycosylation. Glycosylation is the process by which sugar molecules (monosaccharides) and complex chains of sugar molecules (oligosaccharides) are added to proteins and fats. Glycosylation modifies proteins and fats so they can perform a wider variety of functions. The enzyme produced from the ALG6 gene transfers a simple sugar called glucose to the growing oligosaccharide. Once the correct number of sugar molecules are linked together, the oligosaccharide is attached to a protein or fat. ALG6 gene mutations lead to the production of an abnormal enzyme with reduced or no activity. Without a properly functioning enzyme, glycosylation cannot proceed normally, and oligosaccharides are incomplete. As a result, glycosylation is reduced or absent. The wide variety of signs and symptoms in ALG6-CDG are likely due to impaired glycosylation of proteins and fats that are needed for normal function in many organs and tissues, including the brain, eyes, liver, and hormone-producing (endocrine) system. |
inheritance | Is ALG6-congenital disorder of glycosylation inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for ALG6-congenital disorder of glycosylation ? | These resources address the diagnosis or management of ALG6-CDG: - Gene Review: Gene Review: Congenital Disorders of N-Linked Glycosylation Pathway Overview These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) sialuria ? | Sialuria is a rare disorder that has variable effects on development. Affected infants are often born with a yellow tint to the skin and the whites of the eyes (neonatal jaundice), an enlarged liver and spleen (hepatosplenomegaly), and unusually small red blood cells (microcytic anemia). They may develop a somewhat flat face and distinctive-looking facial features that are described as "coarse." Temporarily delayed development and weak muscle tone (hypotonia) have also been reported. Young children with sialuria tend to have frequent upper respiratory infections and episodes of dehydration and stomach upset (gastroenteritis). Older children may have seizures and learning difficulties. In some affected children, intellectual development is nearly normal. The features of sialuria vary widely among affected people. Many of the problems associated with this disorder appear to improve with age, although little is known about the long-term effects of the disease. It is likely that some adults with sialuria never come to medical attention because they have very mild signs and symptoms or no health problems related to the condition. |
frequency | How many people are affected by sialuria ? | Fewer than 10 people worldwide have been diagnosed with sialuria. There are probably more people with the disorder who have not been diagnosed, as sialuria can be difficult to detect because of its variable features. |
genetic changes | What are the genetic changes related to sialuria ? | Mutations in the GNE gene cause sialuria. The GNE gene provides instructions for making an enzyme found in cells and tissues throughout the body. This enzyme is involved in a chemical pathway that produces sialic acid, which is a simple sugar that attaches to the ends of more complex molecules on the surface of cells. By modifying these molecules, sialic acid influences a wide variety of cellular functions including cell movement (migration), attachment of cells to one another (adhesion), signaling between cells, and inflammation. The enzyme produced from the GNE gene is carefully controlled to ensure that cells produce an appropriate amount of sialic acid. A feedback system shuts off the enzyme when no more sialic acid is needed. The mutations responsible for sialuria disrupt this feedback mechanism, resulting in an overproduction of sialic acid. This simple sugar builds up within cells and is excreted in urine. Researchers are working to determine how an accumulation of sialic acid in the body interferes with normal development in people with sialuria. |
inheritance | Is sialuria inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most reported cases have occurred in people with no known history of the disorder in their family and may result from new mutations in the gene. |
treatment | What are the treatments for sialuria ? | These resources address the diagnosis or management of sialuria: - Gene Review: Gene Review: Sialuria - Genetic Testing Registry: Sialuria - MedlinePlus Encyclopedia: Hepatosplenomegaly (image) - MedlinePlus Encyclopedia: Newborn Jaundice These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Schindler disease ? | Schindler disease is an inherited disorder that primarily causes neurological problems. There are three types of Schindler disease. Schindler disease type I, also called the infantile type, is the most severe form. Babies with Schindler disease type I appear healthy at birth, but by the age of 8 to 15 months they stop developing new skills and begin losing skills they had already acquired (developmental regression). As the disorder progresses, affected individuals develop blindness and seizures, and eventually they lose awareness of their surroundings and become unresponsive. People with this form of the disorder usually do not survive past early childhood. Schindler disease type II, also called Kanzaki disease, is a milder form of the disorder that usually appears in adulthood. Affected individuals may develop mild cognitive impairment and hearing loss caused by abnormalities of the inner ear (sensorineural hearing loss). They may experience weakness and loss of sensation due to problems with the nerves connecting the brain and spinal cord to muscles and sensory cells (peripheral nervous system). Clusters of enlarged blood vessels that form small, dark red spots on the skin (angiokeratomas) are characteristic of this form of the disorder. Schindler disease type III is intermediate in severity between types I and II. Affected individuals may exhibit signs and symptoms beginning in infancy, including developmental delay, seizures, a weakened and enlarged heart (cardiomyopathy), and an enlarged liver (hepatomegaly). In other cases, people with this form of the disorder exhibit behavioral problems beginning in early childhood, with some features of autism spectrum disorders. Autism spectrum disorders are characterized by impaired communication and socialization skills. |
frequency | How many people are affected by Schindler disease ? | Schindler disease is very rare. Only a few individuals with each type of the disorder have been identified. |
genetic changes | What are the genetic changes related to Schindler disease ? | Mutations in the NAGA gene cause Schindler disease. The NAGA gene provides instructions for making the enzyme alpha-N-acetylgalactosaminidase. This enzyme works in the lysosomes, which are compartments within cells that digest and recycle materials. Within lysosomes, the enzyme helps break down complexes called glycoproteins and glycolipids, which consist of sugar molecules attached to certain proteins and fats. Specifically, alpha-N-acetylgalactosaminidase helps remove a molecule called alpha-N-acetylgalactosamine from sugars in these complexes. Mutations in the NAGA gene interfere with the ability of the alpha-N-acetylgalactosaminidase enzyme to perform its role in breaking down glycoproteins and glycolipids. These substances accumulate in the lysosomes and cause cells to malfunction and eventually die. Cell damage in the nervous system and other tissues and organs of the body leads to the signs and symptoms of Schindler disease. |
inheritance | Is Schindler disease inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for Schindler disease ? | These resources address the diagnosis or management of Schindler disease: - Genetic Testing Registry: Kanzaki disease - Genetic Testing Registry: Schindler disease, type 1 These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Lynch syndrome ? | Lynch syndrome, often called hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited disorder that increases the risk of many types of cancer, particularly cancers of the colon (large intestine) and rectum, which are collectively referred to as colorectal cancer. People with Lynch syndrome also have an increased risk of cancers of the stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, and skin. Additionally, women with this disorder have a high risk of cancer of the ovaries and lining of the uterus (the endometrium). People with Lynch syndrome may occasionally have noncancerous (benign) growths (polyps) in the colon, called colon polyps. In individuals with this disorder, colon polyps occur earlier but not in greater numbers than they do in the general population. |
frequency | How many people are affected by Lynch syndrome ? | In the United States, about 140,000 new cases of colorectal cancer are diagnosed each year. Approximately 3 to 5 percent of these cancers are caused by Lynch syndrome. |
genetic changes | What are the genetic changes related to Lynch syndrome ? | Variations in the MLH1, MSH2, MSH6, PMS2, or EPCAM gene increase the risk of developing Lynch syndrome. The MLH1, MSH2, MSH6, and PMS2 genes are involved in the repair of mistakes that occur when DNA is copied in preparation for cell division (a process called DNA replication). Mutations in any of these genes prevent the proper repair of DNA replication mistakes. As the abnormal cells continue to divide, the accumulated mistakes can lead to uncontrolled cell growth and possibly cancer. Mutations in the EPCAM gene also lead to impaired DNA repair, although the gene is not itself involved in this process. The EPCAM gene lies next to the MSH2 gene on chromosome 2; certain EPCAM gene mutations cause the MSH2 gene to be turned off (inactivated), interrupting DNA repair and leading to accumulated DNA mistakes. Although mutations in these genes predispose individuals to cancer, not all people who carry these mutations develop cancerous tumors. |
inheritance | Is Lynch syndrome inherited ? | Lynch syndrome cancer risk is inherited in an autosomal dominant pattern, which means one inherited copy of the altered gene in each cell is sufficient to increase cancer risk. It is important to note that people inherit an increased risk of cancer, not the disease itself. Not all people who inherit mutations in these genes will develop cancer. |
treatment | What are the treatments for Lynch syndrome ? | These resources address the diagnosis or management of Lynch syndrome: - American Medical Association and National Coalition for Health Professional Education in Genetics: Understand the Basics of Genetic Testing for Hereditary Colorectal Cancer - Gene Review: Gene Review: Lynch Syndrome - GeneFacts: Lynch Syndrome: Management - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 3 - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 4 - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 5 - Genetic Testing Registry: Hereditary nonpolyposis colorectal cancer type 8 - Genetic Testing Registry: Lynch syndrome - Genetic Testing Registry: Lynch syndrome I - Genetic Testing Registry: Lynch syndrome II - Genomics Education Programme (UK) - MedlinePlus Encyclopedia: Colon Cancer - National Cancer Institute: Genetic Testing for Hereditary Cancer Syndromes These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Gaucher disease ? | Gaucher disease is an inherited disorder that affects many of the body's organs and tissues. The signs and symptoms of this condition vary widely among affected individuals. Researchers have described several types of Gaucher disease based on their characteristic features. Type 1 Gaucher disease is the most common form of this condition. Type 1 is also called non-neuronopathic Gaucher disease because the brain and spinal cord (the central nervous system) are usually not affected. The features of this condition range from mild to severe and may appear anytime from childhood to adulthood. Major signs and symptoms include enlargement of the liver and spleen (hepatosplenomegaly), a low number of red blood cells (anemia), easy bruising caused by a decrease in blood platelets (thrombocytopenia), lung disease, and bone abnormalities such as bone pain, fractures, and arthritis. Types 2 and 3 Gaucher disease are known as neuronopathic forms of the disorder because they are characterized by problems that affect the central nervous system. In addition to the signs and symptoms described above, these conditions can cause abnormal eye movements, seizures, and brain damage. Type 2 Gaucher disease usually causes life-threatening medical problems beginning in infancy. Type 3 Gaucher disease also affects the nervous system, but it tends to worsen more slowly than type 2. The most severe type of Gaucher disease is called the perinatal lethal form. This condition causes severe or life-threatening complications starting before birth or in infancy. Features of the perinatal lethal form can include extensive swelling caused by fluid accumulation before birth (hydrops fetalis); dry, scaly skin (ichthyosis) or other skin abnormalities; hepatosplenomegaly; distinctive facial features; and serious neurological problems. As its name indicates, most infants with the perinatal lethal form of Gaucher disease survive for only a few days after birth. Another form of Gaucher disease is known as the cardiovascular type because it primarily affects the heart, causing the heart valves to harden (calcify). People with the cardiovascular form of Gaucher disease may also have eye abnormalities, bone disease, and mild enlargement of the spleen (splenomegaly). |
frequency | How many people are affected by Gaucher disease ? | Gaucher disease occurs in 1 in 50,000 to 100,000 people in the general population. Type 1 is the most common form of the disorder; it occurs more frequently in people of Ashkenazi (eastern and central European) Jewish heritage than in those with other backgrounds. This form of the condition affects 1 in 500 to 1,000 people of Ashkenazi Jewish heritage. The other forms of Gaucher disease are uncommon and do not occur more frequently in people of Ashkenazi Jewish descent. |
genetic changes | What are the genetic changes related to Gaucher disease ? | Mutations in the GBA gene cause Gaucher disease. The GBA gene provides instructions for making an enzyme called beta-glucocerebrosidase. This enzyme breaks down a fatty substance called glucocerebroside into a sugar (glucose) and a simpler fat molecule (ceramide). Mutations in the GBA gene greatly reduce or eliminate the activity of beta-glucocerebrosidase. Without enough of this enzyme, glucocerebroside and related substances can build up to toxic levels within cells. Tissues and organs are damaged by the abnormal accumulation and storage of these substances, causing the characteristic features of Gaucher disease. |
inheritance | Is Gaucher disease inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for Gaucher disease ? | These resources address the diagnosis or management of Gaucher disease: - Baby's First Test - Gene Review: Gene Review: Gaucher Disease - Genetic Testing Registry: Gaucher disease - MedlinePlus Encyclopedia: Gaucher Disease These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Cockayne syndrome ? | Cockayne syndrome is a rare disorder characterized by short stature and an appearance of premature aging. Features of this disorder include a failure to gain weight and grow at the expected rate (failure to thrive), abnormally small head size (microcephaly), and impaired development of the nervous system. Affected individuals have an extreme sensitivity to sunlight (photosensitivity), and even a small amount of sun exposure can cause a sunburn. Other possible signs and symptoms include hearing loss, eye abnormalities, severe tooth decay, bone abnormalities, and changes in the brain that can be seen on brain scans. Cockayne syndrome can be divided into subtypes, which are distinguished by the severity and age of onset of symptoms. Classical, or type I, Cockayne syndrome is characterized by an onset of symptoms in early childhood (usually after age 1 year). Type II Cockayne syndrome has much more severe symptoms that are apparent at birth (congenital). Type II Cockayne syndrome is sometimes called cerebro-oculo-facio-skeletal (COFS) syndrome or Pena-Shokeir syndrome type II. Type III Cockayne syndrome has the mildest symptoms of the three types and appears later in childhood. |
frequency | How many people are affected by Cockayne syndrome ? | Cockayne syndrome occurs in about 2 per million newborns in the United States and Europe. |
genetic changes | What are the genetic changes related to Cockayne syndrome ? | Cockayne syndrome can result from mutations in either the ERCC6 gene (also known as the CSB gene) or the ERCC8 gene (also known as the CSA gene). These genes provide instructions for making proteins that are involved in repairing damaged DNA. DNA can be damaged by ultraviolet (UV) rays from the sun and by toxic chemicals, radiation, and unstable molecules called free radicals. Cells are usually able to fix DNA damage before it causes problems. However, in people with Cockayne syndrome, DNA damage is not repaired normally. As more abnormalities build up in DNA, cells malfunction and eventually die. The increased cell death likely contributes to the features of Cockayne syndrome, such as growth failure and premature aging. |
inheritance | Is Cockayne syndrome inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for Cockayne syndrome ? | These resources address the diagnosis or management of Cockayne syndrome: - Gene Review: Gene Review: Cockayne Syndrome - Genetic Testing Registry: Cockayne syndrome - Genetic Testing Registry: Cockayne syndrome type A - Genetic Testing Registry: Cockayne syndrome type C - Genetic Testing Registry: Cockayne syndrome, type B - MedlinePlus Encyclopedia: Failure to Thrive These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) actin-accumulation myopathy ? | Actin-accumulation myopathy is a disorder that primarily affects skeletal muscles, which are muscles that the body uses for movement. People with actin-accumulation myopathy have severe muscle weakness (myopathy) and poor muscle tone (hypotonia) throughout the body. Signs and symptoms of this condition are apparent in infancy and include feeding and swallowing difficulties, a weak cry, and difficulty with controlling head movements. Affected babies are sometimes described as "floppy" and may be unable to move on their own. The severe muscle weakness that occurs in actin-accumulation myopathy also affects the muscles used for breathing. Individuals with this disorder may take shallow breaths (hypoventilate), especially during sleep, resulting in a shortage of oxygen and a buildup of carbon dioxide in the blood. Frequent respiratory infections and life-threatening breathing difficulties can occur. Because of the respiratory problems, most affected individuals do not survive past infancy. Those who do survive have delayed development of motor skills such as sitting, crawling, standing, and walking. The name actin-accumulation myopathy derives from characteristic accumulations in muscle cells of filaments composed of a protein called actin. These filaments can be seen when muscle tissue is viewed under a microscope. |
frequency | How many people are affected by actin-accumulation myopathy ? | Actin-accumulation myopathy is a rare disorder that has been identified in only a small number of individuals. Its exact prevalence is unknown. |
genetic changes | What are the genetic changes related to actin-accumulation myopathy ? | Actin-accumulation myopathy is caused by a mutation in the ACTA1 gene. This gene provides instructions for making a protein called skeletal alpha ()-actin, which is a member of the actin protein family found in skeletal muscles. Actin proteins are important for cell movement and the tensing of muscle fibers (muscle contraction). Thin filaments made up of actin molecules and thick filaments made up of another protein called myosin are the primary components of muscle fibers and are important for muscle contraction. Attachment (binding) and release of the overlapping thick and thin filaments allows them to move relative to each other so that the muscles can contract. ACTA1 gene mutations that cause actin-accumulation myopathy may affect the way the skeletal -actin protein binds to ATP. ATP is a molecule that supplies energy for cells' activities, and is important in the formation of thin filaments from individual actin molecules. Dysfunctional actin-ATP binding may result in abnormal thin filament formation and impair muscle contraction, leading to muscle weakness and the other signs and symptoms of actin-accumulation myopathy. In some people with actin-accumulation myopathy, no ACTA1 gene mutations have been identified. The cause of the disorder in these individuals is unknown. |
inheritance | Is actin-accumulation myopathy inherited ? | Actin-accumulation myopathy is an autosomal dominant condition, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases are not inherited; they result from new mutations in the gene and occur in people with no history of the disorder in their family. |
treatment | What are the treatments for actin-accumulation myopathy ? | These resources address the diagnosis or management of actin-accumulation myopathy: - Genetic Testing Registry: Nemaline myopathy 3 These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Hirschsprung disease ? | Hirschsprung disease is an intestinal disorder characterized by the absence of nerves in parts of the intestine. This condition occurs when the nerves in the intestine (enteric nerves) do not form properly during development before birth (embryonic development). This condition is usually identified in the first two months of life, although less severe cases may be diagnosed later in childhood. Enteric nerves trigger the muscle contractions that move stool through the intestine. Without these nerves in parts of the intestine, the material cannot be pushed through, causing severe constipation or complete blockage of the intestine in people with Hirschsprung disease. Other signs and symptoms of this condition include vomiting, abdominal pain or swelling, diarrhea, poor feeding, malnutrition, and slow growth. People with this disorder are at risk of developing more serious conditions such as inflammation of the intestine (enterocolitis) or a hole in the wall of the intestine (intestinal perforation), which can cause serious infection and may be fatal. There are two main types of Hirschsprung disease, known as short-segment disease and long-segment disease, which are defined by the region of the intestine lacking nerve cells. In short-segment disease, nerve cells are missing from only the last segment of the large intestine. This type is most common, occurring in approximately 80 percent of people with Hirschsprung disease. For unknown reasons, short-segment disease is four times more common in men than in women. Long-segment disease occurs when nerve cells are missing from most of the large intestine and is the more severe type. Long-segment disease is found in approximately 20 percent of people with Hirschsprung disease and affects men and women equally. Very rarely, nerve cells are missing from the entire large intestine and sometimes part of the small intestine (total colonic aganglionosis) or from all of the large and small intestine (total intestinal aganglionosis). Hirschsprung disease can occur in combination with other conditions, such as Waardenburg syndrome, type IV; Mowat-Wilson syndrome; or congenital central hypoventilation syndrome. These cases are described as syndromic. Hirschsprung disease can also occur without other conditions, and these cases are referred to as isolated or nonsyndromic. |
frequency | How many people are affected by Hirschsprung disease ? | Hirschsprung disease occurs in approximately 1 in 5,000 newborns. |
genetic changes | What are the genetic changes related to Hirschsprung disease ? | Isolated Hirschsprung disease can result from mutations in one of several genes, including the RET, EDNRB, and EDN3 genes. However, the genetics of this condition appear complex and are not completely understood. While a mutation in a single gene sometimes causes the condition, mutations in multiple genes may be required in some cases. The genetic cause of the condition is unknown in approximately half of affected individuals. Mutations in the RET gene are the most common known genetic cause of Hirschsprung disease. The RET gene provides instructions for producing a protein that is involved in signaling within cells. This protein appears to be essential for the normal development of several kinds of nerve cells, including nerves in the intestine. Mutations in the RET gene that cause Hirschsprung disease result in a nonfunctional version of the RET protein that cannot transmit signals within cells. Without RET protein signaling, enteric nerves do not develop properly. Absence of these nerves leads to the intestinal problems characteristic of Hirschsprung disease. The EDNRB gene provides instructions for making a protein called endothelin receptor type B. When this protein interacts with other proteins called endothelins, it transmits information from outside the cell to inside the cell, signaling for many important cellular processes. The EDN3 gene provides instructions for a protein called endothelin 3, one of the endothelins that interacts with endothelin receptor type B. Together, endothelin 3 and endothelin receptor type B play an important role in the normal formation of enteric nerves. Changes in either the EDNRB gene or the EDN3 gene disrupt the normal functioning of the endothelin receptor type B or the endothelin 3 protein, preventing them from transmitting signals important for the development of enteric nerves. As a result, these nerves do not form normally during embryonic development. A lack of enteric nerves prevents stool from being moved through the intestine, leading to severe constipation and intestinal blockage. |
inheritance | Is Hirschsprung disease inherited ? | Approximately 20 percent of cases of Hirschsprung disease occur in multiple members of the same family. The remainder of cases occur in people with no history of the disorder in their families. Hirschsprung disease appears to have a dominant pattern of inheritance, which means one copy of the altered gene in each cell may be sufficient to cause the disorder. The inheritance is considered to have incomplete penetrance because not everyone who inherits the altered gene from a parent develops Hirschsprung disease. |
treatment | What are the treatments for Hirschsprung disease ? | These resources address the diagnosis or management of Hirschsprung disease: - Cedars-Sinai: Treating Hirschsprung's Disease (Colonic Aganglionosis) - Gene Review: Gene Review: Hirschsprung Disease Overview - Genetic Testing Registry: Hirschsprung disease 1 - Genetic Testing Registry: Hirschsprung disease 2 - Genetic Testing Registry: Hirschsprung disease 3 - Genetic Testing Registry: Hirschsprung disease 4 - North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition: Hirschsprung's Disease - Seattle Children's: Hirschsprung's Disease: Symptoms and Diagnosis These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) fragile X syndrome ? | Fragile X syndrome is a genetic condition that causes a range of developmental problems including learning disabilities and cognitive impairment. Usually, males are more severely affected by this disorder than females. Affected individuals usually have delayed development of speech and language by age 2. Most males with fragile X syndrome have mild to moderate intellectual disability, while about one-third of affected females are intellectually disabled. Children with fragile X syndrome may also have anxiety and hyperactive behavior such as fidgeting or impulsive actions. They may have attention deficit disorder (ADD), which includes an impaired ability to maintain attention and difficulty focusing on specific tasks. About one-third of individuals with fragile X syndrome have features of autism spectrum disorders that affect communication and social interaction. Seizures occur in about 15 percent of males and about 5 percent of females with fragile X syndrome. Most males and about half of females with fragile X syndrome have characteristic physical features that become more apparent with age. These features include a long and narrow face, large ears, a prominent jaw and forehead, unusually flexible fingers, flat feet, and in males, enlarged testicles (macroorchidism) after puberty. |
frequency | How many people are affected by fragile X syndrome ? | Fragile X syndrome occurs in approximately 1 in 4,000 males and 1 in 8,000 females. |
genetic changes | What are the genetic changes related to fragile X syndrome ? | Mutations in the FMR1 gene cause fragile X syndrome. The FMR1 gene provides instructions for making a protein called FMRP. This protein helps regulate the production of other proteins and plays a role in the development of synapses, which are specialized connections between nerve cells. Synapses are critical for relaying nerve impulses. Nearly all cases of fragile X syndrome are caused by a mutation in which a DNA segment, known as the CGG triplet repeat, is expanded within the FMR1 gene. Normally, this DNA segment is repeated from 5 to about 40 times. In people with fragile X syndrome, however, the CGG segment is repeated more than 200 times. The abnormally expanded CGG segment turns off (silences) the FMR1 gene, which prevents the gene from producing FMRP. Loss or a shortage (deficiency) of this protein disrupts nervous system functions and leads to the signs and symptoms of fragile X syndrome. Males and females with 55 to 200 repeats of the CGG segment are said to have an FMR1 gene premutation. Most people with a premutation are intellectually normal. In some cases, however, individuals with a premutation have lower than normal amounts of FMRP. As a result, they may have mild versions of the physical features seen in fragile X syndrome (such as prominent ears) and may experience emotional problems such as anxiety or depression. Some children with a premutation may have learning disabilities or autistic-like behavior. The premutation is also associated with an increased risk of disorders called fragile X-associated primary ovarian insufficiency (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS). |
inheritance | Is fragile X syndrome inherited ? | Fragile X syndrome is inherited in an X-linked dominant pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. (The Y chromosome is the other sex chromosome.) The inheritance is dominant if one copy of the altered gene in each cell is sufficient to cause the condition. X-linked dominant means that in females (who have two X chromosomes), a mutation in one of the two copies of a gene in each cell is sufficient to cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of a gene in each cell causes the disorder. In most cases, males experience more severe symptoms of the disorder than females. In women, the FMR1 gene premutation on the X chromosome can expand to more than 200 CGG repeats in cells that develop into eggs. This means that women with the premutation have an increased risk of having a child with fragile X syndrome. By contrast, the premutation in men does not expand to more than 200 repeats as it is passed to the next generation. Men pass the premutation only to their daughters. Their sons receive a Y chromosome, which does not include the FMR1 gene. |
treatment | What are the treatments for fragile X syndrome ? | These resources address the diagnosis or management of fragile X syndrome: - Gene Review: Gene Review: FMR1-Related Disorders - GeneFacts: Fragile X Syndrome: Diagnosis - GeneFacts: Fragile X Syndrome: Management - Genetic Testing Registry: Fragile X syndrome - MedlinePlus Encyclopedia: Fragile X syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) ZAP70-related severe combined immunodeficiency ? | ZAP70-related severe combined immunodeficiency (SCID) is an inherited disorder that damages the immune system. ZAP70-related SCID is one of several forms of severe combined immunodeficiency, a group of disorders with several genetic causes. Children with SCID lack virtually all immune protection from bacteria, viruses, and fungi. They are prone to repeated and persistent infections that can be very serious or life-threatening. Often the organisms that cause infection in people with this disorder are described as opportunistic because they ordinarily do not cause illness in healthy people. Infants with SCID typically experience pneumonia, chronic diarrhea, and widespread skin rashes. They also grow much more slowly than healthy children. If not treated in a way that restores immune function, children with SCID usually live only a year or two. Most individuals with ZAP70-related SCID are diagnosed in the first 6 months of life. At least one individual first showed signs of the condition later in childhood and had less severe symptoms, primarily recurrent respiratory and skin infections. |
frequency | How many people are affected by ZAP70-related severe combined immunodeficiency ? | ZAP70-related SCID is a rare disorder. Only about 20 affected individuals have been identified. The prevalence of SCID from all genetic causes combined is approximately 1 in 50,000. |
genetic changes | What are the genetic changes related to ZAP70-related severe combined immunodeficiency ? | As the name indicates, this condition is caused by mutations in the ZAP70 gene. The ZAP70 gene provides instructions for making a protein called zeta-chain-associated protein kinase. This protein is part of a signaling pathway that directs the development of and turns on (activates) immune system cells called T cells. T cells identify foreign substances and defend the body against infection. The ZAP70 gene is important for the development and function of several types of T cells. These include cytotoxic T cells (CD8+ T cells), whose functions include destroying cells infected by viruses. The ZAP70 gene is also involved in the activation of helper T cells (CD4+ T cells). These cells direct and assist the functions of the immune system by influencing the activities of other immune system cells. Mutations in the ZAP70 gene prevent the production of zeta-chain-associated protein kinase or result in a protein that is unstable and cannot perform its function. A loss of functional zeta-chain-associated protein kinase leads to the absence of CD8+ T cells and an excess of inactive CD4+ T cells. The resulting shortage of active T cells causes people with ZAP70-related SCID to be more susceptible to infection. |
inheritance | Is ZAP70-related severe combined immunodeficiency inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for ZAP70-related severe combined immunodeficiency ? | These resources address the diagnosis or management of ZAP70-related severe combined immunodeficiency: - Baby's First Test: Severe Combined Immunodeficiency - Gene Review: Gene Review: ZAP70-Related Severe Combined Immunodeficiency - Genetic Testing Registry: Severe combined immunodeficiency, atypical These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Cant syndrome ? | Cant syndrome is a rare condition characterized by excess hair growth (hypertrichosis), a distinctive facial appearance, heart defects, and several other abnormalities. The features of the disorder vary among affected individuals. People with Cant syndrome have thick scalp hair that extends onto the forehead and grows down onto the cheeks in front of the ears. They also have increased body hair, especially on the back, arms, and legs. Most affected individuals have a large head (macrocephaly) and distinctive facial features that are described as "coarse." These include a broad nasal bridge, skin folds covering the inner corner of the eyes (epicanthal folds), and a wide mouth with full lips. As affected individuals get older, the face lengthens, the chin becomes more prominent, and the eyes become deep-set. Many infants with Cant syndrome are born with a heart defect such as an enlarged heart (cardiomegaly) or patent ductus arteriosus (PDA). The ductus arteriosus is a connection between two major arteries, the aorta and the pulmonary artery. This connection is open during fetal development and normally closes shortly after birth. However, the ductus arteriosus remains open, or patent, in babies with PDA. Other heart problems have also been found in people with Cant syndrome, including an abnormal buildup of fluid around the heart (pericardial effusion) and high blood pressure in the blood vessels that carry blood from the heart to the lungs (pulmonary hypertension). Additional features of this condition include distinctive skeletal abnormalities, a large body size (macrosomia) at birth, a reduced amount of fat under the skin (subcutaneous fat) beginning in childhood, deep horizontal creases in the palms of the hands and soles of the feet, and an increased susceptibility to respiratory infections. Other signs and symptoms that have been reported include abnormal swelling in the body's tissues (lymphedema), side-to-side curvature of the spine (scoliosis), and reduced bone density (osteopenia). Some affected children have weak muscle tone (hypotonia) that delays the development of motor skills such as sitting, standing, and walking. Most have mildly delayed speech, and some affected children have mild intellectual disability or learning problems. |
frequency | How many people are affected by Cant syndrome ? | Cant syndrome is a rare condition. About three dozen affected individuals have been reported in the medical literature. |
genetic changes | What are the genetic changes related to Cant syndrome ? | Cant syndrome results from mutations in the ABCC9 gene. This gene provides instructions for making one part (subunit) of a channel that transports charged potassium atoms (potassium ions) across cell membranes. Mutations in the ABCC9 gene alter the structure of the potassium channel, which causes the channel to open when it should be closed. It is unknown how this problem with potassium channel function leads to excess hair growth, heart defects, and the other features of Cant syndrome. |
inheritance | Is Cant syndrome inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered ABCC9 gene in each cell is sufficient to cause the disorder. Most cases result from new mutations in the gene and occur in people with no history of the disorder in their family. In a few reported cases, an affected person has inherited the mutation from one affected parent. |
treatment | What are the treatments for Cant syndrome ? | These resources address the diagnosis or management of Cant syndrome: - Gene Review: Gene Review: Cant syndrome - Genetic Testing Registry: Hypertrichotic osteochondrodysplasia These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Russell-Silver syndrome ? | Russell-Silver syndrome is a growth disorder characterized by slow growth before and after birth. Babies with this condition have a low birth weight and often fail to grow and gain weight at the expected rate (failure to thrive). Head growth is normal, however, so the head may appear unusually large compared to the rest of the body. Affected children are thin and have poor appetites, and some develop low blood sugar (hypoglycemia) as a result of feeding difficulties. Adults with Russell-Silver syndrome are short; the average height for affected males is about 151 centimeters (4 feet, 11 inches) and the average height for affected females is about 140 centimeters (4 feet, 7 inches). Many children with Russell-Silver syndrome have a small, triangular face with distinctive facial features including a prominent forehead, a narrow chin, a small jaw, and downturned corners of the mouth. Other features of this disorder can include an unusual curving of the fifth finger (clinodactyly), asymmetric or uneven growth of some parts of the body, and digestive system abnormalities. Russell-Silver syndrome is also associated with an increased risk of delayed development and learning disabilities. |
frequency | How many people are affected by Russell-Silver syndrome ? | The exact incidence of Russell-Silver syndrome is unknown, but the condition is estimated to affect 1 in 75,000 to 100,000 people. |
genetic changes | What are the genetic changes related to Russell-Silver syndrome ? | The genetic causes of Russell-Silver syndrome are complex. The disorder often results from the abnormal regulation of certain genes that control growth. Research has focused on genes located in particular regions of chromosome 7 and chromosome 11. People normally inherit one copy of each chromosome from their mother and one copy from their father. For most genes, both copies are expressed, or "turned on," in cells. For some genes, however, only the copy inherited from a person's father (the paternal copy) is expressed. For other genes, only the copy inherited from a person's mother (the maternal copy) is expressed. These parent-specific differences in gene expression are caused by a phenomenon called genomic imprinting. Both chromosome 7 and chromosome 11 contain groups of genes that normally undergo genomic imprinting. Abnormalities involving these genes appear to be responsible for many cases of Russell-Silver syndrome. Researchers suspect that at least one third of all cases of Russell-Silver syndrome result from changes in a process called methylation. Methylation is a chemical reaction that attaches small molecules called methyl groups to certain segments of DNA. In genes that undergo genomic imprinting, methylation is one way that a gene's parent of origin is marked during the formation of egg and sperm cells. Russell-Silver syndrome has been associated with changes in methylation involving the H19 and IGF2 genes, which are located near one another on chromosome 11. These genes are thought to be involved in directing normal growth. A loss of methylation disrupts the regulation of these genes, which leads to slow growth and the other characteristic features of this disorder. Abnormalities involving genes on chromosome 7 also cause Russell-Silver syndrome. In 7 percent to 10 percent of cases, people inherit both copies of chromosome 7 from their mother instead of one copy from each parent. This phenomenon is called maternal uniparental disomy (UPD). Maternal UPD causes people to have two active copies of maternally expressed imprinted genes rather than one active copy from the mother and one inactive copy from the father. These individuals do not have a paternal copy of chromosome 7 and therefore do not have any copies of genes that are active only on the paternal copy. In cases of Russell-Silver syndrome caused by maternal UPD, an imbalance in active paternal and maternal genes on chromosome 7 underlies the signs and symptoms of the disorder. In at least 40 percent of people with Russell-Silver syndrome, the cause of the condition is unknown. It is possible that changes in chromosomes other than 7 and 11 may play a role. Researchers are working to identify additional genetic changes that underlie this disorder. |
inheritance | Is Russell-Silver syndrome inherited ? | Most cases of Russell-Silver syndrome are sporadic, which means they occur in people with no history of the disorder in their family. Less commonly, Russell-Silver syndrome can run in families. In some affected families, the condition appears to have an autosomal dominant pattern of inheritance. Autosomal dominant inheritance means one copy of a genetic change in each cell is sufficient to cause the disorder. In other families, the condition has an autosomal recessive pattern of inheritance. Autosomal recessive inheritance means both copies of a gene are altered in each cell. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for Russell-Silver syndrome ? | These resources address the diagnosis or management of Russell-Silver syndrome: - Gene Review: Gene Review: Russell-Silver Syndrome - Genetic Testing Registry: Russell-Silver syndrome - MedlinePlus Encyclopedia: Russell-Silver syndrome These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Hennekam syndrome ? | Hennekam syndrome is an inherited disorder resulting from malformation of the lymphatic system, which is part of both the circulatory system and immune system. The lymphatic system consists of a network of vessels that transport lymph fluid and immune cells throughout the body. The characteristic signs and symptoms of Hennekam syndrome are lymphatic vessels that are abnormally expanded (lymphangiectasia), particularly the vessels that transport lymph fluid to and from the intestines; puffiness or swelling caused by a buildup of fluid (lymphedema); and unusual facial features. Lymphangiectasia often impedes the flow of lymph fluid and can cause the affected vessels to break open (rupture). In the intestines, ruptured vessels can lead to accumulation of lymph fluid, which interferes with the absorption of nutrients, fats, and proteins. Accumulation of lymph fluid in the abdomen can cause swelling (chylous ascites). Lymphangiectasia can also affect the kidneys, thyroid gland, the outer covering of the lungs (the pleura), the membrane covering the heart (pericardium), or the skin. The lymphedema in Hennekam syndrome is often noticeable at birth and usually affects the face and limbs. Severely affected infants may have extensive swelling caused by fluid accumulation before birth (hydrops fetalis). The lymphedema usually affects one side of the body more severely than the other (asymmetric) and slowly worsens over time. Facial features of people with Hennekam syndrome may include a flattened appearance to the middle of the face and the bridge of the nose, puffy eyelids, widely spaced eyes (hypertelorism), small ears, and a small mouth with overgrowth of the gums (gingival hypertrophy). Affected individuals may also have an unusually small head (microcephaly) and premature fusion of the skull bones (craniosynostosis). Individuals with Hennekam syndrome often have intellectual disability that ranges from mild to severe, although most are on the mild end of the range and some have normal intellect. Many individuals with Hennekam syndrome have growth delay, respiratory problems, permanently bent fingers and toes (camptodactyly), or fusion of the skin between the fingers and toes (cutaneous syndactyly). Abnormalities found in a few individuals with Hennekam syndrome include a moderate to severe shortage of red blood cells (anemia) resulting from an inadequate amount (deficiency) of iron in the bloodstream, multiple spleens (polysplenia), misplaced kidneys, genital anomalies, a soft out-pouching around the belly-button (umbilical hernia), heart abnormalities, hearing loss, excessive body hair growth (hirsutism), a narrow upper chest that may have a sunken appearance (pectus excavatum), an abnormal side-to-side curvature of the spine (scoliosis), and inward- and upward-turning feet (clubfeet). The signs and symptoms of Hennekam syndrome vary widely among affected individuals, even those within the same family. Life expectancy depends on the severity of the condition and can vary from death in childhood to survival into adulthood. |
frequency | How many people are affected by Hennekam syndrome ? | At least 50 cases of Hennekam syndrome have been reported worldwide. |
genetic changes | What are the genetic changes related to Hennekam syndrome ? | Mutations in the CCBE1 or FAT4 gene can cause Hennekam syndrome. The CCBE1 gene provides instructions for making a protein that is found in the lattice of proteins and other molecules outside the cell (extracellular matrix). The CCBE1 protein is involved in the maturation (differentiation) and movement (migration) of immature cells called lymphangioblasts that will eventually form the lining (epithelium) of lymphatic vessels. The function of the protein produced from the FAT4 gene is largely unknown. Research shows that the FAT4 protein may be involved in determining the position of various components within cells (cell polarity). CCBE1 gene mutations that cause Hennekam syndrome change the three-dimensional shape of the protein and severely decrease its function. The abnormal protein cannot play its role in the formation of the lymphatic vessel epithelium. The resulting malformation of lymphatic vessels leads to lymphangiectasia, lymphedema, and other features of Hennekam syndrome. Since the lymphatic system extends throughout the body, a disruption to the vessels can affect almost any organ. Altered lymphatic development before birth may change the balance of fluids and impair normal development, contributing to many of the other signs of Hennekam syndrome such as unusual facial features. FAT4 gene mutations that cause Hennekam syndrome result in a FAT4 protein with decreased function. Reduced FAT4 protein activity seems to impair normal development of the lymphatic system, but the mechanism is unknown. Together, mutations in the CCBE1 and FAT4 genes are responsible for approximately half of all Hennekam syndrome cases. The cause of the remaining cases is unknown. |
inheritance | Is Hennekam syndrome inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for Hennekam syndrome ? | These resources address the diagnosis or management of Hennekam syndrome: - Great Ormond Street Hospital for Children (UK): Primary Intestinal Lymphangiectasia Information - Johns Hopkins Medicine: Lymphedema Management - VascularWeb: Lymphedema These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) eosinophil peroxidase deficiency ? | Eosinophil peroxidase deficiency is a condition that affects certain white blood cells called eosinophils but causes no health problems in affected individuals. Eosinophils aid in the body's immune response. During a normal immune response, these cells are turned on (activated), and they travel to the area of injury or inflammation. The cells then release proteins and other compounds that have a toxic effect on severely damaged cells or invading organisms. One of these proteins is called eosinophil peroxidase. In eosinophil peroxidase deficiency, eosinophils have little or no eosinophil peroxidase. A lack of this protein does not seem to affect the eosinophils' ability to carry out an immune response. Because eosinophil peroxidase deficiency does not cause any health problems, this condition is often diagnosed when blood tests are done for other reasons or when a family member has been diagnosed with the condition. |
frequency | How many people are affected by eosinophil peroxidase deficiency ? | Approximately 100 individuals with eosinophil peroxidase deficiency have been described in the scientific literature. Based on blood test data, varying estimates of the prevalence of the condition have been reported in specific populations. Eosinophil peroxidase deficiency is estimated to occur in 8.6 in 1,000 Yemenite Jews, in 3 in 1,000 North-African Jews, and in 1 in 1,000 Iraqi Jews. In northeastern Italy, the condition occurs in approximately 1 in 14,000 individuals; in Japan it occurs in 1 in 36,000 people; and in Luxembourg, eosinophil peroxidase deficiency is thought to occur in 1 in 100,000 people. |
genetic changes | What are the genetic changes related to eosinophil peroxidase deficiency ? | Mutations in the EPX gene cause eosinophil peroxidase deficiency. The EPX gene provides instructions for making the eosinophil peroxidase protein. During an immune response, activated eosinophils release eosinophil peroxidase at the site of injury. This protein helps form molecules that are highly toxic to bacteria and parasites. These toxic molecules also play a role in regulating inflammation by fighting microbial invaders. EPX gene mutations reduce or prevent eosinophil peroxidase production or result in a protein that is unstable and nonfunctional. As a result, eosinophils have severely reduced amounts of eosinophil peroxidase or none at all. Other proteins within affected eosinophils are normal, and while the cells lacking eosinophil peroxidase are smaller and may have structural changes, the loss of eosinophil peroxidase does not appear to impair the function of eosinophils. |
inheritance | Is eosinophil peroxidase deficiency inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for eosinophil peroxidase deficiency ? | These resources address the diagnosis or management of eosinophil peroxidase deficiency: - Genetic Testing Registry: Eosinophil peroxidase deficiency - Tulane University Eosinophilic Disorder Center These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Friedreich ataxia ? | Friedreich ataxia is a genetic condition that affects the nervous system and causes movement problems. People with this condition develop impaired muscle coordination (ataxia) that worsens over time. Other features of this condition include the gradual loss of strength and sensation in the arms and legs, muscle stiffness (spasticity), and impaired speech. Individuals with Friedreich ataxia often have a form of heart disease called hypertrophic cardiomyopathy that enlarges and weakens the heart muscle. Some affected individuals develop diabetes, impaired vision, hearing loss, or an abnormal curvature of the spine (scoliosis). Most people with Friedreich ataxia begin to experience the signs and symptoms of the disorder around puberty. Poor balance when walking and slurred speech are often the first noticeable features. Affected individuals typically require the use of a wheelchair about 10 years after signs and symptoms appear. About 25 percent of people with Friedreich ataxia have an atypical form that begins after age 25. Affected individuals who develop Friedreich ataxia between ages 26 and 39 are considered to have late-onset Friedreich ataxia (LOFA). When the signs and symptoms begin after age 40 the condition is called very late-onset Friedreich ataxia (VLOFA). LOFA and VLOFA usually progress more slowly than typical Friedreich ataxia. |
frequency | How many people are affected by Friedreich ataxia ? | Friedreich ataxia is estimated to affect 1 in 40,000 people. This condition is found in people with European, Middle Eastern, or North African ancestry. It is rarely identified in other ethnic groups. |
genetic changes | What are the genetic changes related to Friedreich ataxia ? | Mutations in the FXN gene cause Friedreich ataxia. This gene provides instructions for making a protein called frataxin. Although its role is not fully understood, frataxin appears to be important for the normal function of mitochondria, the energy-producing centers within cells. One region of the FXN gene contains a segment of DNA known as a GAA trinucleotide repeat. This segment is made up of a series of three DNA building blocks (one guanine and two adenines) that appear multiple times in a row. Normally, this segment is repeated 5 to 33 times within the FXN gene. In people with Friedreich ataxia, the GAA segment is repeated 66 to more than 1,000 times. The length of the GAA trinucleotide repeat appears to be related to the age at which the symptoms of Friedreich ataxia appear. People with GAA segments repeated fewer than 300 times tend to have a later appearance of symptoms (after age 25) than those with larger GAA trinucleotide repeats. The abnormally long GAA trinucleotide repeat disrupts the production of frataxin, which severely reduces the amount of this protein in cells. Certain nerve and muscle cells cannot function properly with a shortage of frataxin, leading to the characteristic signs and symptoms of Friedreich ataxia. |
inheritance | Is Friedreich ataxia inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for Friedreich ataxia ? | These resources address the diagnosis or management of Friedreich ataxia: - Friedreich's Ataxia Research Alliance: Clinical Care Guidelines - Gene Review: Gene Review: Friedreich Ataxia - Genetic Testing Registry: Friedreich ataxia 1 - MedlinePlus Encyclopedia: Friedreich's Ataxia - MedlinePlus Encyclopedia: Hypertrophic Cardiomyopathy - National Institute of Neurological Disorders and Stroke: Friedreich's Ataxia Fact Sheet These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care |
information | What is (are) Meesmann corneal dystrophy ? | Meesmann corneal dystrophy is an eye disease that affects the cornea, which is the clear front covering of the eye. This condition is characterized by the formation of tiny round cysts in the outermost layer of the cornea, called the corneal epithelium. This part of the cornea acts as a barrier to help prevent foreign materials, such as dust and bacteria, from entering the eye. In people with Meesmann corneal dystrophy, cysts can appear as early as the first year of life. They usually affect both eyes and increase in number over time. The cysts usually do not cause any symptoms until late adolescence or adulthood, when they start to break open (rupture) on the surface of the cornea and cause irritation. The resulting symptoms typically include increased sensitivity to light (photophobia), twitching of the eyelids (blepharospasm), increased tear production, the sensation of having a foreign object in the eye, and an inability to tolerate wearing contact lenses. Some affected individuals also have temporary episodes of blurred vision. |
frequency | How many people are affected by Meesmann corneal dystrophy ? | Meesmann corneal dystrophy is a rare disorder whose prevalence is unknown. It was first described in a large, multi-generational German family with more than 100 affected members. Since then, the condition has been reported in individuals and families worldwide. |
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