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genetic changes | What are the genetic changes related to Werner syndrome ? | Mutations in the WRN gene cause Werner syndrome. The WRN gene provides instructions for producing the Werner protein, which is thought to perform several tasks related to the maintenance and repair of DNA. This protein also assists in the process of copying (replicating) DNA in preparation for cell division. Mutations in the WRN gene often lead to the production of an abnormally short, nonfunctional Werner protein. Research suggests that this shortened protein is not transported to the cell's nucleus, where it normally interacts with DNA. Evidence also suggests that the altered protein is broken down more quickly in the cell than the normal Werner protein. Researchers do not fully understand how WRN mutations cause the signs and symptoms of Werner syndrome. Cells with an altered Werner protein may divide more slowly or stop dividing earlier than normal, causing growth problems. Also, the altered protein may allow DNA damage to accumulate, which could impair normal cell activities and cause the health problems associated with this condition. |
inheritance | Is Werner syndrome inherited ? | Werner syndrome is inherited in an autosomal recessive pattern, which means both copies of the WRN gene in each cell have mutations. The parents of an individual with Werner syndrome 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 Werner syndrome ? | These resources address the diagnosis or management of Werner syndrome: - Gene Review: Gene Review: Werner Syndrome - Genetic Testing Registry: Werner 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) X-linked infantile spasm syndrome ? | X-linked infantile spasm syndrome is a seizure disorder characterized by a type of seizure known as infantile spasms. The spasms usually appear before the age of 1. Several types of spasms have been described, but the most commonly reported involves bending at the waist and neck with extension of the arms and legs (sometimes called a jackknife spasm). Each spasm lasts only seconds, but they occur in clusters several minutes long. Although individuals are not usually affected while they are sleeping, the spasms commonly occur just after awakening. Infantile spasms usually disappear by age 5, but many children then develop other types of seizures that recur throughout their lives. Most babies with X-linked infantile spasm syndrome have characteristic results on an electroencephalogram (EEG), a test used to measure the electrical activity of the brain. The EEG of these individuals typically shows an irregular pattern known as hypsarrhythmia, and this finding can help differentiate infantile spasms from other types of seizures. Because of the recurrent seizures, babies with X-linked infantile spasm syndrome stop developing normally and begin to lose skills they have acquired (developmental regression), such as sitting, rolling over, and babbling. Subsequently, development in affected children is delayed. Most affected individuals also have intellectual disability throughout their lives. |
frequency | How many people are affected by X-linked infantile spasm syndrome ? | Infantile spasms are estimated to affect 1 to 1.6 in 100,000 individuals. This estimate includes X-linked infantile spasm syndrome as well as infantile spasms that have other causes. |
genetic changes | What are the genetic changes related to X-linked infantile spasm syndrome ? | X-linked infantile spasm syndrome is caused by mutations in either the ARX gene or the CDKL5 gene. The proteins produced from these genes play a role in the normal functioning of the brain. The ARX protein is involved in the regulation of other genes that contribute to brain development. The CDKL5 protein is thought to regulate the activity of at least one protein that is critical for normal brain function. Researchers are working to determine how mutations in either of these genes lead to seizures and intellectual disability. Infantile spasms can have nongenetic causes, such as brain malformations, other disorders that affect brain function, or brain damage. In addition, changes in genes that are not located on the X chromosome cause infantile spasms in rare cases. |
inheritance | Is X-linked infantile spasm syndrome inherited ? | X-linked infantile spasm syndrome can have different inheritance patterns depending on the genetic cause. When caused by mutations in the ARX gene, this condition is inherited in an X-linked recessive pattern. The ARX gene is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. Usually in females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. However, in some instances, one altered copy of the ARX gene is sufficient because the X chromosome with the normal copy of the ARX gene is turned off through a process called X-inactivation. Early in embryonic development in females, one of the two X chromosomes is permanently inactivated in somatic cells (cells other than egg and sperm cells). X-inactivation ensures that females, like males, have only one active copy of the X chromosome in each body cell. Usually X-inactivation occurs randomly, such that each X chromosome is active in about half of the body cells. Sometimes X-inactivation is not random, and one X chromosome is active in more than half of cells. When X-inactivation does not occur randomly, it is called skewed X-inactivation. Some ARX gene mutations may be associated with skewed X-inactivation, which results in the inactivation of the X chromosome with the normal copy of the ARX gene in most cells of the body. This skewed X-inactivation causes the chromosome with the mutated ARX gene to be expressed in more than half of cells, causing X-linked infantile spasm syndrome. When caused by mutations in the CDKL5 gene, this condition is thought to have an X-linked dominant inheritance pattern. The CDKL5 gene is also located on the X chromosome, making this condition X-linked. The inheritance is dominant because one copy of the altered gene in each cell is sufficient to cause the condition in both males and females. X-linked infantile spasm syndrome caused by CDKL5 gene mutations usually occurs in individuals with no history of the disorder in their family. These mutations likely occur in early embryonic development (called de novo mutations). Because males have only one X chromosome, X-linked dominant disorders are often more severe in males than in females. Male fetuses with CDKL5-related X-linked infantile spasm syndrome may not survive to birth, so more females are diagnosed with the condition. In females, the distribution of active and inactive X chromosomes due to X-inactivation may affect whether a woman develops the condition or the severity of the signs and symptoms. Generally, the larger the proportion of active X chromosomes that contain the mutated CDKL5 gene, the more severe the signs and symptoms of the condition are. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. |
treatment | What are the treatments for X-linked infantile spasm syndrome ? | These resources address the diagnosis or management of X-linked infantile spasm syndrome: - Child Neurology Foundation - Genetic Testing Registry: Early infantile epileptic encephalopathy 2 - Genetic Testing Registry: West 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) Knobloch syndrome ? | Knobloch syndrome is a rare condition characterized by severe vision problems and a skull defect. A characteristic feature of Knobloch syndrome is extreme nearsightedness (high myopia). In addition, several other eye abnormalities are common in people with this condition. Most affected individuals have vitreoretinal degeneration, which is breakdown (degeneration) of two structures in the eye called the vitreous and the retina. The vitreous is the gelatin-like substance that fills the eye, and the retina is the light-sensitive tissue at the back of the eye. Vitreoretinal degeneration often leads to separation of the retina from the back of the eye (retinal detachment). Affected individuals may also have abnormalities in the central area of the retina, called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. Due to abnormalities in the vitreous, retina, and macula, people with Knobloch syndrome often develop blindness in one or both eyes. Another characteristic feature of Knobloch syndrome is a skull defect called an occipital encephalocele, which is a sac-like protrusion of the brain (encephalocele) through a defect in the bone at the base of the skull (occipital bone). Some affected individuals have been diagnosed with a different skull defect in the occipital region, and it is unclear whether the defect is always a true encephalocele. In other conditions, encephaloceles may be associated with intellectual disability; however, most people with Knobloch syndrome have normal intelligence. |
frequency | How many people are affected by Knobloch syndrome ? | Knobloch syndrome is a rare condition. However, the exact prevalence of the condition is unknown. |
genetic changes | What are the genetic changes related to Knobloch syndrome ? | Mutations in the COL18A1 gene can cause Knobloch syndrome. The COL18A1 gene provides instructions for making a protein that forms collagen XVIII, which is found in the basement membranes of tissues throughout the body. Basement membranes are thin, sheet-like structures that separate and support cells in these tissues. Collagen XVIII is found in the basement membranes of several parts of the eye, including the vitreous and retina, among other tissues. Little is known about the function of this protein, but it appears to be involved in normal development of the eye. Several mutations in the COL18A1 gene have been identified in people with Knobloch syndrome. Most COL18A1 gene mutations lead to an abnormally short version of the genetic blueprint used to make the collagen XVIII protein. Although the process is unclear, the COL18A1 gene mutations result in the loss of collagen XVIII protein, which likely causes the signs and symptoms of Knobloch syndrome. When the condition is caused by COL18A1 gene mutations, it is sometimes referred to as Knobloch syndrome type I. Research indicates that mutations in at least two other genes that have not been identified may cause Knobloch syndrome types II and III. Although they are caused by alterations in different genes, the three types of the condition have similar signs and symptoms. |
inheritance | Is Knobloch 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 Knobloch syndrome ? | These resources address the diagnosis or management of Knobloch syndrome: - American Academy of Ophthalmology: Eye Smart - Genetic Testing Registry: Knobloch syndrome 1 - JAMA Patient Page: Retinal Detachment - National Eye Institute: Facts About Retinal Detachment - Prevent Blindness America: Retinal Tears and Detachments 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) Stevens-Johnson syndrome/toxic epidermal necrolysis ? | Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a severe skin reaction most often triggered by particular medications. Although Stevens-Johnson syndrome and toxic epidermal necrolysis were once thought to be separate conditions, they are now considered part of a continuum. Stevens-Johnson syndrome represents the less severe end of the disease spectrum, and toxic epidermal necrolysis represents the more severe end. SJS/TEN often begins with a fever and flu-like symptoms. Within a few days, the skin begins to blister and peel, forming very painful raw areas called erosions that resemble a severe hot-water burn. The skin erosions usually start on the face and chest before spreading to other parts of the body. In most affected individuals, the condition also damages the mucous membranes, including the lining of the mouth and the airways, which can cause trouble with swallowing and breathing. The painful blistering can also affect the urinary tract and genitals. SJS/TEN often affects the eyes as well, causing irritation and redness of the conjunctiva, which are the mucous membranes that protect the white part of the eye and line the eyelids, and damage to the clear front covering of the eye (the cornea). Severe damage to the skin and mucous membranes makes SJS/TEN a life-threatening disease. Because the skin normally acts as a protective barrier, extensive skin damage can lead to a dangerous loss of fluids and allow infections to develop. Serious complications can include pneumonia, overwhelming bacterial infections (sepsis), shock, multiple organ failure, and death. About 10 percent of people with Stevens-Johnson syndrome die from the disease, while the condition is fatal in up to 50 percent of those with toxic epidermal necrolysis. Among people who survive, long-term effects of SJS/TEN can include changes in skin coloring (pigmentation), dryness of the skin and mucous membranes (xerosis), excess sweating (hyperhidrosis), hair loss (alopecia), and abnormal growth or loss of the fingernails and toenails. Other long-term problems can include impaired taste, difficulty urinating, and genital abnormalities. A small percentage of affected individuals develop chronic dryness or inflammation of the eyes, which can lead to increased sensitivity to light (photophobia) and vision impairment. |
frequency | How many people are affected by Stevens-Johnson syndrome/toxic epidermal necrolysis ? | SJS/TEN is a rare disease, affecting 1 to 2 per million people each year. Stevens-Johnson syndrome (the less severe form of the condition) is more common than toxic epidermal necrolysis. People who are HIV-positive and those with a chronic inflammatory disease called systemic lupus erythematosus are more likely to develop SJS/TEN than the general population. The reason for the increased risk is unclear, but immune system factors and exposure to multiple medications may play a role. |
genetic changes | What are the genetic changes related to Stevens-Johnson syndrome/toxic epidermal necrolysis ? | Several genetic changes have been found to increase the risk of SJS/TEN in response to triggering factors such as medications. Most of these changes occur in genes that are involved in the normal function of the immune system. The genetic variations most strongly associated with SJS/TEN occur in the HLA-B gene. This gene is part of a family of genes called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders (such as viruses and bacteria). The HLA-B gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign proteins. Certain variations in this gene occur much more often in people with SJS/TEN than in people without the condition. Studies suggest that the HLA-B gene variations associated with SJS/TEN cause the immune system to react abnormally to certain medications. In a process that is not well understood, the drug causes immune cells called cytotoxic T cells and natural killer (NK) cells to release a substance called granulysin that destroys cells in the skin and mucous membranes. The death of these cells causes the blistering and peeling that is characteristic of SJS/TEN. Variations in several other HLA and non-HLA genes have also been studied as potential risk factors for SJS/TEN. However, most people with genetic variations that increase the risk of SJS/TEN never develop the disease, even if they are exposed to drugs that can trigger it. Researchers believe that additional genetic and nongenetic factors, many of which are unknown, likely play a role in whether a particular individual develops SJS/TEN. The drugs most frequently associated with SJS/TEN include several medications that are used to treat seizures (particularly carbamazepine, lamotrigine, and phenytoin); allopurinol, which is used to treat kidney stones and a form of arthritis called gout; a class of antibiotic drugs called sulfonamides; nevirapine, which is used to treat HIV infection; and a type of non-steroidal anti-inflammatory drugs (NSAIDs) called oxicams. Other factors may also trigger SJS/TEN. In particular, these skin reactions have occurred in people with an unusual form of pneumonia caused by infection with Mycoplasma pneumoniae and in people with viral infections, including cytomegalovirus. Researchers suspect that a combination of infections and drugs could contribute to the disease in some individuals. In many cases, no definitive trigger for an individual's SJS/TEN is ever discovered. |
inheritance | Is Stevens-Johnson syndrome/toxic epidermal necrolysis inherited ? | SJS/TEN is not an inherited condition. However, the genetic changes that increase the risk of developing SJS/TEN can be passed from one generation to the next. |
treatment | What are the treatments for Stevens-Johnson syndrome/toxic epidermal necrolysis ? | These resources address the diagnosis or management of Stevens-Johnson syndrome/toxic epidermal necrolysis: - Genetic Testing Registry: Stevens-Johnson syndrome - Genetic Testing Registry: Toxic epidermal necrolysis 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) benign recurrent intrahepatic cholestasis ? | Benign recurrent intrahepatic cholestasis (BRIC) is characterized by episodes of liver dysfunction called cholestasis. During these episodes, the liver cells have a reduced ability to release a digestive fluid called bile. Because the problems with bile release occur within the liver (intrahepatic), the condition is described as intrahepatic cholestasis. Episodes of cholestasis can last from weeks to months, and the time between episodes, during which there are usually no symptoms, can vary from weeks to years. The first episode of cholestasis usually occurs in an affected person's teens or twenties. An attack typically begins with severe itchiness (pruritus), followed by yellowing of the skin and whites of the eyes (jaundice) a few weeks later. Other general signs and symptoms that occur during these episodes include a vague feeling of discomfort (malaise), irritability, nausea, vomiting, and a lack of appetite. A common feature of BRIC is the reduced absorption of fat in the body, which leads to excess fat in the feces (steatorrhea). Because of a lack of fat absorption and loss of appetite, affected individuals often lose weight during episodes of cholestasis. BRIC is divided into two types, BRIC1 and BRIC2, based on the genetic cause of the condition. The signs and symptoms are the same in both types. This condition is called benign because it does not cause lasting damage to the liver. However, episodes of liver dysfunction occasionally develop into a more severe, permanent form of liver disease known as progressive familial intrahepatic cholestasis (PFIC). BRIC and PFIC are sometimes considered to be part of a spectrum of intrahepatic cholestasis disorders of varying severity. |
frequency | How many people are affected by benign recurrent intrahepatic cholestasis ? | BRIC is a rare disorder. Although the prevalence is unknown, this condition is less common than the related disorder PFIC, which affects approximately 1 in 50,000 to 100,000 people worldwide. |
genetic changes | What are the genetic changes related to benign recurrent intrahepatic cholestasis ? | Mutations in the ATP8B1 gene cause benign recurrent intrahepatic cholestasis type 1 (BRIC1), and mutations in the ABCB11 gene cause benign recurrent intrahepatic cholestasis type 2 (BRIC2). These two genes are involved in the release (secretion) of bile, a fluid produced by the liver that helps digest fats. The ATP8B1 gene provides instructions for making a protein that helps to control the distribution of certain fats, called lipids, in the membranes of liver cells. This function likely plays a role in maintaining an appropriate balance of bile acids, a component of bile. This process, known as bile acid homeostasis, is critical for the normal secretion of bile and the proper functioning of liver cells. Although the mechanism is unclear, mutations in the ATP8B1 gene result in the buildup of bile acids in liver cells. The imbalance of bile acids leads to the signs and symptoms of BRIC1. The ABCB11 gene provides instructions for making a protein called the bile salt export pump (BSEP). This protein is found in the liver, and its main role is to move bile salts (a component of bile) out of liver cells. Mutations in the ABCB11 gene result in a reduction of BSEP function. This reduction leads to a decrease of bile salt secretion, which causes the features of BRIC2. The factors that trigger episodes of BRIC are unknown. Some people with BRIC do not have a mutation in the ATP8B1 or ABCB11 gene. In these individuals, the cause of the condition is unknown. |
inheritance | Is benign recurrent intrahepatic cholestasis inherited ? | Both types of BRIC are 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. Some people with BRIC have no family history of the disorder. These cases arise from mutations in the ATP8B1 or ABCB11 gene that occur in the body's cells after conception and are not inherited. |
treatment | What are the treatments for benign recurrent intrahepatic cholestasis ? | These resources address the diagnosis or management of benign recurrent intrahepatic cholestasis: - Gene Review: Gene Review: ATP8B1 Deficiency - Genetic Testing Registry: Benign recurrent intrahepatic cholestasis 1 - Genetic Testing Registry: Benign recurrent intrahepatic cholestasis 2 - Merck Manual Home Health Edition: Cholestasis 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) Wilson disease ? | Wilson disease is an inherited disorder in which excessive amounts of copper accumulate in the body, particularly in the liver, brain, and eyes. The signs and symptoms of Wilson disease usually first appear between the ages of 6 and 45, but they most often begin during the teenage years. The features of this condition include a combination of liver disease and neurological and psychiatric problems. Liver disease is typically the initial feature of Wilson disease in affected children and young adults; individuals diagnosed at an older age usually do not have symptoms of liver problems, although they may have very mild liver disease. The signs and symptoms of liver disease include yellowing of the skin or whites of the eyes (jaundice), fatigue, loss of appetite, and abdominal swelling. Nervous system or psychiatric problems are often the initial features in individuals diagnosed in adulthood and commonly occur in young adults with Wilson disease. Signs and symptoms of these problems can include clumsiness, tremors, difficulty walking, speech problems, impaired thinking ability, depression, anxiety, and mood swings. In many individuals with Wilson disease, copper deposits in the front surface of the eye (the cornea) form a green-to-brownish ring, called the Kayser-Fleischer ring, that surrounds the colored part of the eye. Abnormalities in eye movements, such as a restricted ability to gaze upwards, may also occur. |
frequency | How many people are affected by Wilson disease ? | Wilson disease is a rare disorder that affects approximately 1 in 30,000 individuals. |
genetic changes | What are the genetic changes related to Wilson disease ? | Wilson disease is caused by mutations in the ATP7B gene. This gene provides instructions for making a protein called copper-transporting ATPase 2, which plays a role in the transport of copper from the liver to other parts of the body. Copper is necessary for many cellular functions, but it is toxic when present in excessive amounts. The copper-transporting ATPase 2 protein is particularly important for the elimination of excess copper from the body. Mutations in the ATP7B gene prevent the transport protein from functioning properly. With a shortage of functional protein, excess copper is not removed from the body. As a result, copper accumulates to toxic levels that can damage tissues and organs, particularly the liver and brain. Research indicates that a normal variation in the PRNP gene may modify the course of Wilson disease. The PRNP gene provides instructions for making prion protein, which is active in the brain and other tissues and appears to be involved in transporting copper. Studies have focused on the effects of a PRNP gene variation that affects position 129 of the prion protein. At this position, people can have either the protein building block (amino acid) methionine or the amino acid valine. Among people who have mutations in the ATP7B gene, it appears that having methionine instead of valine at position 129 of the prion protein is associated with delayed onset of symptoms and an increased occurrence of neurological symptoms, particularly tremors. Larger studies are needed, however, before the effects of this PRNP gene variation on Wilson disease can be established. |
inheritance | Is Wilson 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 Wilson disease ? | These resources address the diagnosis or management of Wilson disease: - Gene Review: Gene Review: Wilson Disease - Genetic Testing Registry: Wilson's disease - MedlinePlus Encyclopedia: Wilson's disease - National Human Genome Research Institute 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) beta thalassemia ? | Beta thalassemia is a blood disorder that reduces the production of hemoglobin. Hemoglobin is the iron-containing protein in red blood cells that carries oxygen to cells throughout the body. In people with beta thalassemia, low levels of hemoglobin lead to a lack of oxygen in many parts of the body. Affected individuals also have a shortage of red blood cells (anemia), which can cause pale skin, weakness, fatigue, and more serious complications. People with beta thalassemia are at an increased risk of developing abnormal blood clots. Beta thalassemia is classified into two types depending on the severity of symptoms: thalassemia major (also known as Cooley's anemia) and thalassemia intermedia. Of the two types, thalassemia major is more severe. The signs and symptoms of thalassemia major appear within the first 2 years of life. Children develop life-threatening anemia. They do not gain weight and grow at the expected rate (failure to thrive) and may develop yellowing of the skin and whites of the eyes (jaundice). Affected individuals may have an enlarged spleen, liver, and heart, and their bones may be misshapen. Some adolescents with thalassemia major experience delayed puberty. Many people with thalassemia major have such severe symptoms that they need frequent blood transfusions to replenish their red blood cell supply. Over time, an influx of iron-containing hemoglobin from chronic blood transfusions can lead to a buildup of iron in the body, resulting in liver, heart, and hormone problems. Thalassemia intermedia is milder than thalassemia major. The signs and symptoms of thalassemia intermedia appear in early childhood or later in life. Affected individuals have mild to moderate anemia and may also have slow growth and bone abnormalities. |
frequency | How many people are affected by beta thalassemia ? | Beta thalassemia is a fairly common blood disorder worldwide. Thousands of infants with beta thalassemia are born each year. Beta thalassemia occurs most frequently in people from Mediterranean countries, North Africa, the Middle East, India, Central Asia, and Southeast Asia. |
genetic changes | What are the genetic changes related to beta thalassemia ? | Mutations in the HBB gene cause beta thalassemia. The HBB gene provides instructions for making a protein called beta-globin. Beta-globin is a component (subunit) of hemoglobin. Hemoglobin consists of four protein subunits, typically two subunits of beta-globin and two subunits of another protein called alpha-globin. Some mutations in the HBB gene prevent the production of any beta-globin. The absence of beta-globin is referred to as beta-zero (B0) thalassemia. Other HBB gene mutations allow some beta-globin to be produced but in reduced amounts. A reduced amount of beta-globin is called beta-plus (B+) thalassemia. Having either B0 or B+ thalassemia does not necessarily predict disease severity, however; people with both types have been diagnosed with thalassemia major and thalassemia intermedia. A lack of beta-globin leads to a reduced amount of functional hemoglobin. Without sufficient hemoglobin, red blood cells do not develop normally, causing a shortage of mature red blood cells. The low number of mature red blood cells leads to anemia and other associated health problems in people with beta thalassemia. |
inheritance | Is beta thalassemia inherited ? | Thalassemia major and thalassemia intermedia are inherited in an autosomal recessive pattern, which means both copies of the HBB 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. Sometimes, however, people with only one HBB gene mutation in each cell develop mild anemia. These mildly affected people are said to have thalassemia minor. In a small percentage of families, the HBB gene mutation is inherited in an autosomal dominant manner. In these cases, one copy of the altered gene in each cell is sufficient to cause the signs and symptoms of beta thalassemia. |
treatment | What are the treatments for beta thalassemia ? | These resources address the diagnosis or management of beta thalassemia: - Gene Review: Gene Review: Beta-Thalassemia - Genetic Testing Registry: Beta-thalassemia, dominant inclusion body type - Genetic Testing Registry: beta Thalassemia - MedlinePlus Encyclopedia: Thalassemia 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) esophageal atresia/tracheoesophageal fistula ? | Esophageal atresia/tracheoesophageal fistula (EA/TEF) is a condition resulting from abnormal development before birth of the tube that carries food from the mouth to the stomach (the esophagus). During early development, the esophagus and windpipe (trachea) begin as a single tube that normally divides into the two adjacent passages between four and eight weeks after conception. If this separation does not occur properly, EA/TEF is the result. In esophageal atresia (EA), the upper esophagus does not connect (atresia) to the lower esophagus and stomach. Almost 90 percent of babies born with esophageal atresia also have a tracheoesophageal fistula (TEF), in which the esophagus and the trachea are abnormally connected, allowing fluids from the esophagus to get into the airways and interfere with breathing. A small number of infants have only one of these abnormalities. There are several types of EA/TEF, classified by the location of the malformation and the structures that are affected. In more than 80 percent of cases, the lower section of the malformed esophagus is connected to the trachea (EA with a distal TEF). Other possible configurations include having the upper section of the malformed esophagus connected to the trachea (EA with a proximal TEF), connections to the trachea from both the upper and lower sections of the malformed esophagus (EA with proximal and distal TEF), an esophagus that is malformed but does not connect to the trachea (isolated EA), and a connection to the trachea from an otherwise normal esophagus (H-type TEF with no EA). While EA/TEF arises during fetal development, it generally becomes apparent shortly after birth. Saliva, liquids fed to the infant, or digestive fluids may enter the windpipe through the tracheoesophageal fistula, leading to coughing, respiratory distress, and a bluish appearance of the skin or lips (cyanosis). Esophageal atresia blocks liquids fed to the infant from entering the stomach, so they are spit back up, sometimes along with fluids from the respiratory tract. EA/TEF is a life-threatening condition; affected babies generally require surgery to correct the malformation in order to allow feeding and prevent lung damage from repeated exposure to esophageal fluids. EA/TEF occurs alone (isolated EA/TEF) in about 40 percent of affected individuals. In other cases it occurs with other birth defects or as part of a genetic syndrome (non-isolated or syndromic EA/TEF). |
frequency | How many people are affected by esophageal atresia/tracheoesophageal fistula ? | EA/TEF occurs in 1 in 3,000 to 5,000 newborns. |
genetic changes | What are the genetic changes related to esophageal atresia/tracheoesophageal fistula ? | Isolated EA/TEF is considered to be a multifactorial condition, which means that multiple gene variations and environmental factors likely contribute to its occurrence. In most cases of isolated EA/TEF, no specific genetic changes or environmental factors have been conclusively determined to be the cause. Non-isolated or syndromic forms of EA/TEF can be caused by changes in single genes or in chromosomes, or they can be multifactorial. For example, approximately 10 percent of people with CHARGE syndrome, which is usually caused by mutations in the CHD7 gene, have EA/TEF. About 25 percent of individuals with the chromosomal abnormality trisomy 18 are born with EA/TEF. EA/TEF also occurs in VACTERL association, a multifactorial condition. VACTERL is an acronym that stands for vertebral defects, anal atresia, cardiac defects, tracheoesophageal fistula, renal anomalies, and limb abnormalities. People diagnosed with VACTERL association typically have at least three of these features; between 50 and 80 percent have a tracheoesophageal fistula. |
inheritance | Is esophageal atresia/tracheoesophageal fistula inherited ? | When EA/TEF occurs as a feature of a genetic syndrome or chromosomal abnormality, it may cluster in families according to the inheritance pattern for that condition. Often EA/TEF is not inherited, and there is only one affected individual in a family. |
treatment | What are the treatments for esophageal atresia/tracheoesophageal fistula ? | These resources address the diagnosis or management of EA/TEF: - Boston Children's Hospital: Esophageal Atresia - Children's Hospital of Wisconsin - Gene Review: Gene Review: Esophageal Atresia/Tracheoesophageal Fistula Overview - Genetic Testing Registry: Tracheoesophageal fistula - MedlinePlus Encyclopedia: Tracheoesophageal Fistula and Esophageal Atresia Repair - University of California, San Francisco (UCSF) Medical 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) PDGFRB-associated chronic eosinophilic leukemia ? | PDGFRB-associated chronic eosinophilic leukemia is a type of cancer of blood-forming cells. It is characterized by an elevated number of white blood cells called eosinophils in the blood. These cells help fight infections by certain parasites and are involved in the inflammation associated with allergic reactions. However, these circumstances do not account for the increased number of eosinophils in PDGFRB-associated chronic eosinophilic leukemia. Some people with this condition have an increased number of other types of white blood cells, such as neutrophils or mast cells, in addition to eosinophils. People with this condition can have an enlarged spleen (splenomegaly) or enlarged liver (hepatomegaly). Some affected individuals develop skin rashes, likely as a result of an abnormal immune response due to the increased number of eosinophils. |
frequency | How many people are affected by PDGFRB-associated chronic eosinophilic leukemia ? | The exact prevalence of PDGFRB-associated chronic eosinophilic leukemia is unknown. For unknown reasons, males are up to nine times more likely than females to develop PDGFRB-associated chronic eosinophilic leukemia. |
genetic changes | What are the genetic changes related to PDGFRB-associated chronic eosinophilic leukemia ? | PDGFRB-associated chronic eosinophilic leukemia is caused by genetic rearrangements that join part of the PDGFRB gene with part of another gene. At least 20 genes have been found that fuse with the PDGFRB gene to cause PDGFRB-associated chronic eosinophilic leukemia. The most common genetic abnormality in this condition results from a rearrangement (translocation) of genetic material that brings part of the PDGFRB gene on chromosome 5 together with part of the ETV6 gene on chromosome 12, creating the ETV6-PDGFRB fusion gene. The PDGFRB gene provides instructions for making a protein that plays a role in turning on (activating) signaling pathways that control many cell processes, including cell growth and division (proliferation). The ETV6 gene provides instructions for making a protein that turns off (represses) gene activity. This protein is important in development before birth and in regulating blood cell formation. The protein produced from the ETV6-PDGFRB fusion gene, called ETV6/PDGFR, functions differently than the proteins normally produced from the individual genes. Like the normal PDGFR protein, the ETV6/PDGFR fusion protein turns on signaling pathways. However, the fusion protein does not need to be turned on to be active, so the signaling pathways are constantly turned on (constitutively activated). The fusion protein is unable to repress gene activity regulated by the normal ETV6 protein, so gene activity is increased. The constitutively active signaling pathways and abnormal gene activity increase the proliferation and survival of cells. When the ETV6-PDGFRB fusion gene mutation occurs in cells that develop into blood cells, the growth of eosinophils (and occasionally other blood cells, such as neutrophils and mast cells) is poorly controlled, leading to PDGFRB-associated chronic eosinophilic leukemia. It is unclear why eosinophils are preferentially affected by this genetic change. |
inheritance | Is PDGFRB-associated chronic eosinophilic leukemia inherited ? | PDGFRB-associated chronic eosinophilic leukemia is not inherited and occurs in people with no history of the condition in their families. Chromosomal rearrangements that lead to a PDGFRB fusion gene are somatic mutations, which are mutations acquired during a person's lifetime and present only in certain cells. The somatic mutation occurs initially in a single cell, which continues to grow and divide, producing a group of cells with the same mutation (a clonal population). |
treatment | What are the treatments for PDGFRB-associated chronic eosinophilic leukemia ? | These resources address the diagnosis or management of PDGFRB-associated chronic eosinophilic leukemia: - Cancer.Net: Leukemia--Eosinophilic: Treatment - Genetic Testing Registry: Myeloproliferative disorder, chronic, with eosinophilia - MedlinePlus Encyclopedia: Eosinophil Count--Absolute - Seattle Cancer Care Alliance: Hypereosinophilia 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) androgen insensitivity syndrome ? | Androgen insensitivity syndrome is a condition that affects sexual development before birth and during puberty. People with this condition are genetically male, with one X chromosome and one Y chromosome in each cell. Because their bodies are unable to respond to certain male sex hormones (called androgens), they may have mostly female sex characteristics or signs of both male and female sexual development. Complete androgen insensitivity syndrome occurs when the body cannot use androgens at all. People with this form of the condition have the external sex characteristics of females, but do not have a uterus and therefore do not menstruate and are unable to conceive a child (infertile). They are typically raised as females and have a female gender identity. Affected individuals have male internal sex organs (testes) that are undescended, which means they are abnormally located in the pelvis or abdomen. Undescended testes can become cancerous later in life if they are not surgically removed. People with complete androgen insensitivity syndrome also have sparse or absent hair in the pubic area and under the arms. The partial and mild forms of androgen insensitivity syndrome result when the body's tissues are partially sensitive to the effects of androgens. People with partial androgen insensitivity (also called Reifenstein syndrome) can have normal female sex characteristics, both male and female sex characteristics, or normal male sex characteristics. They may be raised as males or as females, and may have a male or a female gender identity. People with mild androgen insensitivity are born with male sex characteristics, but are often infertile and tend to experience breast enlargement at puberty. |
frequency | How many people are affected by androgen insensitivity syndrome ? | Complete androgen insensitivity syndrome affects 2 to 5 per 100,000 people who are genetically male. Partial androgen insensitivity is thought to be at least as common as complete androgen insensitivity. Mild androgen insensitivity is much less common. |
genetic changes | What are the genetic changes related to androgen insensitivity syndrome ? | Mutations in the AR gene cause androgen insensitivity syndrome. This gene provides instructions for making a protein called an androgen receptor. Androgen receptors allow cells to respond to androgens, which are hormones (such as testosterone) that direct male sexual development. Androgens and androgen receptors also have other important functions in both males and females, such as regulating hair growth and sex drive. Mutations in the AR gene prevent androgen receptors from working properly, which makes cells less responsive to androgens or prevents cells from using these hormones at all. Depending on the level of androgen insensitivity, an affected person's sex characteristics can vary from mostly female to mostly male. |
inheritance | Is androgen insensitivity syndrome inherited ? | This condition is inherited in an X-linked recessive 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 in each cell. In genetic males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In genetic females (who have two X chromosomes), a mutation must be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. About two-thirds of all cases of androgen insensitivity syndrome are inherited from mothers who carry an altered copy of the AR gene on one of their two X chromosomes. The remaining cases result from a new mutation that can occur in the mother's egg cell before the child is conceived or during early fetal development. |
treatment | What are the treatments for androgen insensitivity syndrome ? | These resources address the diagnosis or management of androgen insensitivity syndrome: - Gene Review: Gene Review: Androgen Insensitivity Syndrome - Genetic Testing Registry: Androgen resistance syndrome - MedlinePlus Encyclopedia: Androgen Insensitivity Syndrome - MedlinePlus Encyclopedia: Intersex - MedlinePlus Encyclopedia: Reifenstein 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) spondyloenchondrodysplasia with immune dysregulation ? | Spondyloenchondrodysplasia with immune dysregulation (SPENCDI) is an inherited condition that primarily affects bone growth and immune system function. The signs and symptoms of SPENCDI can become apparent anytime from infancy to adolescence. Bone abnormalities in individuals with SPENCDI include flattened spinal bones (platyspondyly), abnormalities at the ends of long bones in the limbs (metaphyseal dysplasia), and areas of damage (lesions) on the long bones and spinal bones that can be seen on x-rays. Additional skeletal problems occur because of abnormalities of the tough, flexible tissue called cartilage that makes up much of the skeleton during early development. Individuals with SPENCDI often have areas where cartilage did not convert to bone. They may also have noncancerous growths of cartilage (enchondromas). The bone and cartilage problems contribute to short stature in people with SPENCDI. Individuals with SPENCDI have a combination of immune system problems. Many affected individuals have malfunctioning immune systems that attack the body's own tissues and organs, which is known as an autoimmune reaction. The malfunctioning immune system can lead to a variety of disorders, such as a decrease in blood cells called platelets (thrombocytopenia), premature destruction of red blood cells (hemolytic anemia), an underactive thyroid gland (hypothyroidism), or chronic inflammatory disorders such as systemic lupus erythematosus or rheumatoid arthritis. In addition, affected individuals often have abnormal immune cells that cannot grow and divide in response to harmful invaders such as bacteria and viruses. As a result of this immune deficiency, these individuals have frequent fevers and recurrent respiratory infections. Some people with SPENCDI have neurological problems such as abnormal muscle stiffness (spasticity), difficulty with coordinating movements (ataxia), and intellectual disability. They may also have abnormal deposits of calcium (calcification) in the brain. Due to the range of immune system problems, people with SPENCDI typically have a shortened life expectancy, but figures vary widely. |
frequency | How many people are affected by spondyloenchondrodysplasia with immune dysregulation ? | SPENCDI appears to be a rare condition, although its prevalence is unknown. |
genetic changes | What are the genetic changes related to spondyloenchondrodysplasia with immune dysregulation ? | Mutations in the ACP5 gene cause SPENCDI. This gene provides instructions for making an enzyme called tartrate-resistant acid phosphatase type 5 (TRAP). The TRAP enzyme primarily regulates the activity of a protein called osteopontin, which is produced in bone cells called osteoclasts and in immune cells. Osteopontin performs a variety of functions in these cells. Osteoclasts are specialized cells that break down and remove (resorb) bone tissue that is no longer needed. These cells are involved in bone remodeling, which is a normal process that replaces old bone tissue with new bone. During bone remodeling, osteopontin is turned on (activated), allowing osteoclasts to attach (bind) to bones. When the breakdown of bone is complete, TRAP turns off (inactivates) osteopontin, causing the osteoclasts to release themselves from bone. In immune system cells, osteopontin helps fight infection by promoting inflammation, regulating immune cell activity, and turning on various immune system cells that are necessary to fight off foreign invaders. As in bone cells, the TRAP enzyme inactivates osteopontin in immune cells when it is no longer needed. The ACP5 gene mutations that cause SPENCDI impair or eliminate TRAP's ability to inactivate osteopontin. As a result, osteopontin is abnormally active, prolonging bone breakdown by osteoclasts and triggering abnormal inflammation and immune responses by immune cells. In people with SPENCDI, increased bone remodeling contributes to the skeletal abnormalities, including irregularly shaped bones and short stature. An overactive immune system leads to increased susceptibility to autoimmune disorders and impairs the body's normal immune response to harmful invaders, resulting in frequent infections. The mechanism that leads to the other features of SPENCDI, including movement disorders and intellectual disability, is currently unknown. |
inheritance | Is spondyloenchondrodysplasia with immune dysregulation 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 spondyloenchondrodysplasia with immune dysregulation ? | 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) oculodentodigital dysplasia ? | Oculodentodigital dysplasia is a condition that affects many parts of the body, particularly the eyes (oculo-), teeth (dento-), and fingers (digital). Common features in people with this condition are small eyes (microphthalmia) and other eye abnormalities that can lead to vision loss. Affected individuals also frequently have tooth abnormalities, such as small or missing teeth, weak enamel, multiple cavities, and early tooth loss. Other common features of this condition include a thin nose and webbing of the skin (syndactyly) between the fourth and fifth fingers. Less common features of oculodentodigital dysplasia include sparse hair growth (hypotrichosis), brittle nails, an unusual curvature of the fingers (camptodactyly), syndactyly of the toes, small head size (microcephaly), and an opening in the roof of the mouth (cleft palate). Some affected individuals experience neurological problems such as a lack of bladder or bowel control, difficulty coordinating movements (ataxia), abnormal muscle stiffness (spasticity), hearing loss, and impaired speech (dysarthria). A few people with oculodentodigital dysplasia also have a skin condition called palmoplantar keratoderma. Palmoplantar keratoderma causes the skin on the palms and the soles of the feet to become thick, scaly, and calloused. Some features of oculodentodigital dysplasia are evident at birth, while others become apparent with age. |
frequency | How many people are affected by oculodentodigital dysplasia ? | The exact incidence of oculodentodigital dysplasia is unknown. It has been diagnosed in fewer than 1,000 people worldwide. More cases are likely undiagnosed. |
genetic changes | What are the genetic changes related to oculodentodigital dysplasia ? | Mutations in the GJA1 gene cause oculodentodigital dysplasia. The GJA1 gene provides instructions for making a protein called connexin43. This protein forms one part (a subunit) of channels called gap junctions, which allow direct communication between cells. Gap junctions formed by connexin43 proteins are found in many tissues throughout the body. GJA1 gene mutations result in abnormal connexin43 proteins. Channels formed with abnormal proteins are often permanently closed. Some mutations prevent connexin43 proteins from traveling to the cell surface where they are needed to form channels between cells. Impaired functioning of these channels disrupts cell-to-cell communication, which likely interferes with normal cell growth and cell specialization, processes that determine the shape and function of many different parts of the body. These developmental problems cause the signs and symptoms of oculodentodigital dysplasia. |
inheritance | Is oculodentodigital dysplasia inherited ? | Most cases of oculodentodigital dysplasia are 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. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family. Less commonly, oculodentodigital dysplasia can be 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. Fewer than ten cases of autosomal recessive oculodentodigital dysplasia have been reported. |
treatment | What are the treatments for oculodentodigital dysplasia ? | These resources address the diagnosis or management of oculodentodigital dysplasia: - Genetic Testing Registry: Oculodentodigital dysplasia - MedlinePlus Encyclopedia: Webbing of the fingers or toes - UC Davis Children's Hospital: Cleft and Craniofacial Reconstruction 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) cone-rod dystrophy ? | Cone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with cone-rod dystrophy, vision loss occurs as the light-sensing cells of the retina gradually deteriorate. The first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). These features are typically followed by impaired color vision (dyschromatopsia), blind spots (scotomas) in the center of the visual field, and partial side (peripheral) vision loss. Over time, affected individuals develop night blindness and a worsening of their peripheral vision, which can limit independent mobility. Decreasing visual acuity makes reading increasingly difficult and most affected individuals are legally blind by mid-adulthood. As the condition progresses, individuals may develop involuntary eye movements (nystagmus). There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, or X-linked (each of which is described below). Additionally, cone-rod dystrophy can occur alone without any other signs and symptoms or it can occur as part of a syndrome that affects multiple parts of the body. |
frequency | How many people are affected by cone-rod dystrophy ? | Cone-rod dystrophy is estimated to affect 1 in 30,000 to 40,000 individuals. |
genetic changes | What are the genetic changes related to cone-rod dystrophy ? | Mutations in approximately 30 genes are known to cause cone-rod dystrophy. Approximately 20 of these genes are associated with the form of cone-rod dystrophy that is inherited in an autosomal recessive pattern. Mutations in the ABCA4 gene are the most common cause of autosomal recessive cone-rod dystrophy, accounting for 30 to 60 percent of cases. At least 10 genes have been associated with cone-rod dystrophy that is inherited in an autosomal dominant pattern. Mutations in the GUCY2D and CRX genes account for about half of these cases. Changes in at least two genes cause the X-linked form of the disorder, which is rare. The genes associated with cone-rod dystrophy play essential roles in the structure and function of specialized light receptor cells (photoreceptors) in the retina. The retina contains two types of photoreceptors, rods and cones. Rods are needed for vision in low light, while cones provide vision in bright light, including color vision. Mutations in any of the genes associated with cone-rod dystrophy lead to a gradual loss of rods and cones in the retina. The progressive degeneration of these cells causes the characteristic pattern of vision loss that occurs in people with cone-rod dystrophy. Cones typically break down before rods, which is why sensitivity to light and impaired color vision are usually the first signs of the disorder. (The order of cell breakdown is also reflected in the condition name.) Night vision is disrupted later, as rods are lost. Some of the genes associated with cone-rod dystrophy are also associated with other eye diseases, including a group of related eye disorders called rod-cone dystrophy. Rod-cone dystrophy has signs and symptoms similar to those of cone-rod dystrophy. However, rod-cone dystrophy is characterized by deterioration of the rods first, followed by the cones, so night vision is affected before daylight and color vision. The most common form of rod-cone dystrophy is a condition called retinitis pigmentosa. |
inheritance | Is cone-rod dystrophy inherited ? | Cone-rod dystrophy is usually 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. Less frequently, 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 of these cases, an affected person has one parent with the condition. Rarely, cone-rod dystrophy is inherited in an X-linked recessive pattern. The genes associated with this form of the condition are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. Females with one copy of the altered gene have mild vision problems, such as decreased visual acuity. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. |
treatment | What are the treatments for cone-rod dystrophy ? | These resources address the diagnosis or management of cone-rod dystrophy: - Cleveland Clinic: Eye Examinations: What to Expect - Genetic Testing Registry: CONE-ROD DYSTROPHY, AIPL1-RELATED - Genetic Testing Registry: Cone-rod dystrophy - Genetic Testing Registry: Cone-rod dystrophy 1 - Genetic Testing Registry: Cone-rod dystrophy 10 - Genetic Testing Registry: Cone-rod dystrophy 11 - Genetic Testing Registry: Cone-rod dystrophy 12 - Genetic Testing Registry: Cone-rod dystrophy 13 - Genetic Testing Registry: Cone-rod dystrophy 15 - Genetic Testing Registry: Cone-rod dystrophy 16 - Genetic Testing Registry: Cone-rod dystrophy 17 - Genetic Testing Registry: Cone-rod dystrophy 18 - Genetic Testing Registry: Cone-rod dystrophy 19 - Genetic Testing Registry: Cone-rod dystrophy 2 - Genetic Testing Registry: Cone-rod dystrophy 20 - Genetic Testing Registry: Cone-rod dystrophy 21 - Genetic Testing Registry: Cone-rod dystrophy 3 - Genetic Testing Registry: Cone-rod dystrophy 5 - Genetic Testing Registry: Cone-rod dystrophy 6 - Genetic Testing Registry: Cone-rod dystrophy 7 - Genetic Testing Registry: Cone-rod dystrophy 8 - Genetic Testing Registry: Cone-rod dystrophy 9 - Genetic Testing Registry: Cone-rod dystrophy X-linked 3 - Genetic Testing Registry: Cone-rod dystrophy, X-linked 1 - MedlinePlus Encyclopedia: Color Vision Test - MedlinePlus Encyclopedia: Visual Acuity Test - MedlinePlus Encyclopedia: Visual Field Test 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) multiple endocrine neoplasia ? | Multiple endocrine neoplasia is a group of disorders that affect the body's network of hormone-producing glands (the endocrine system). Hormones are chemical messengers that travel through the bloodstream and regulate the function of cells and tissues throughout the body. Multiple endocrine neoplasia typically involves tumors (neoplasia) in at least two endocrine glands; tumors can also develop in other organs and tissues. These growths can be noncancerous (benign) or cancerous (malignant). If the tumors become cancerous, the condition can be life-threatening. The major forms of multiple endocrine neoplasia are called type 1, type 2, and type 4. These types are distinguished by the genes involved, the types of hormones made, and the characteristic signs and symptoms. Many different types of tumors are associated with multiple endocrine neoplasia. Type 1 frequently involves tumors of the parathyroid glands, the pituitary gland, and the pancreas. Tumors in these glands can lead to the overproduction of hormones. The most common sign of multiple endocrine neoplasia type 1 is overactivity of the parathyroid glands (hyperparathyroidism). Hyperparathyroidism disrupts the normal balance of calcium in the blood, which can lead to kidney stones, thinning of bones, nausea and vomiting, high blood pressure (hypertension), weakness, and fatigue. The most common sign of multiple endocrine neoplasia type 2 is a form of thyroid cancer called medullary thyroid carcinoma. Some people with this disorder also develop a pheochromocytoma, which is an adrenal gland tumor that can cause dangerously high blood pressure. Multiple endocrine neoplasia type 2 is divided into three subtypes: type 2A, type 2B (formerly called type 3), and familial medullary thyroid carcinoma (FMTC). These subtypes differ in their characteristic signs and symptoms and risk of specific tumors; for example, hyperparathyroidism occurs only in type 2A, and medullary thyroid carcinoma is the only feature of FMTC. The signs and symptoms of multiple endocrine neoplasia type 2 are relatively consistent within any one family. Multiple endocrine neoplasia type 4 appears to have signs and symptoms similar to those of type 1, although it is caused by mutations in a different gene. Hyperparathyroidism is the most common feature, followed by tumors of the pituitary gland, additional endocrine glands, and other organs. |
frequency | How many people are affected by multiple endocrine neoplasia ? | Multiple endocrine neoplasia type 1 affects about 1 in 30,000 people; multiple endocrine neoplasia type 2 affects an estimated 1 in 35,000 people. Among the subtypes of type 2, type 2A is the most common form, followed by FMTC. Type 2B is relatively uncommon, accounting for about 5 percent of all cases of type 2. The prevalence of multiple endocrine neoplasia type 4 is unknown, although the condition appears to be rare. |
genetic changes | What are the genetic changes related to multiple endocrine neoplasia ? | Mutations in the MEN1, RET, and CDKN1B genes can cause multiple endocrine neoplasia. Mutations in the MEN1 gene cause multiple endocrine neoplasia type 1. This gene provides instructions for producing a protein called menin. Menin acts as a tumor suppressor, which means it normally keeps cells from growing and dividing too rapidly or in an uncontrolled way. Although the exact function of menin is unknown, it is likely involved in cell functions such as copying and repairing DNA and regulating the activity of other genes. When mutations inactivate both copies of the MEN1 gene, menin is no longer available to control cell growth and division. The loss of functional menin allows cells to divide too frequently, leading to the formation of tumors characteristic of multiple endocrine neoplasia type 1. It is unclear why these tumors preferentially affect endocrine tissues. Mutations in the RET gene cause multiple endocrine neoplasia type 2. This gene provides instructions for producing a protein that is involved in signaling within cells. The RET protein triggers chemical reactions that instruct cells to respond to their environment, for example by dividing or maturing. Mutations in the RET gene overactivate the protein's signaling function, which can trigger cell growth and division in the absence of signals from outside the cell. This unchecked cell division can lead to the formation of tumors in endocrine glands and other tissues. Mutations in the CDKN1B gene cause multiple endocrine neoplasia type 4. This gene provides instructions for making a protein called p27. Like the menin protein, p27 is a tumor suppressor that helps control the growth and division of cells. Mutations in the CDKN1B gene reduce the amount of functional p27, which allows cells to grow and divide unchecked. This unregulated cell division can lead to the development of tumors in endocrine glands and other tissues. |
inheritance | Is multiple endocrine neoplasia inherited ? | Most cases of multiple endocrine neoplasia type 1 are considered to have an autosomal dominant pattern of inheritance. People with this condition are born with one mutated copy of the MEN1 gene in each cell. In most cases, the altered gene is inherited from an affected parent. The remaining cases are a result of new mutations in the MEN1 gene, and occur in people with no history of the disorder in their family. Unlike most other autosomal dominant conditions, in which one altered copy of a gene in each cell is sufficient to cause the disorder, two copies of the MEN1 gene must be altered to trigger tumor formation in multiple endocrine neoplasia type 1. A mutation in the second copy of the MEN1 gene occurs in a small number of cells during a person's lifetime. Almost everyone who is born with one MEN1 mutation acquires a second mutation in certain cells, which can then divide in an unregulated way to form tumors. Multiple endocrine neoplasia type 2 and type 4 are also inherited in an autosomal dominant pattern. In these cases, one copy of the mutated gene is sufficient to cause the disorder. Affected individuals often inherit an altered RET or CDKN1B gene from one parent with the condition. Some cases, however, result from new mutations in the gene and occur in people without other affected family members. |
treatment | What are the treatments for multiple endocrine neoplasia ? | These resources address the diagnosis or management of multiple endocrine neoplasia: - Gene Review: Gene Review: Multiple Endocrine Neoplasia Type 1 - Gene Review: Gene Review: Multiple Endocrine Neoplasia Type 2 - Genetic Testing Registry: Familial medullary thyroid carcinoma - Genetic Testing Registry: Multiple endocrine neoplasia, type 1 - Genetic Testing Registry: Multiple endocrine neoplasia, type 2a - Genetic Testing Registry: Multiple endocrine neoplasia, type 2b - Genetic Testing Registry: Multiple endocrine neoplasia, type 4 - Genomics Education Programme (UK): Multiple Endocrine Neoplasia type 1 - Genomics Education Programme (UK): Multiple Endocrine Neoplasia type 2A - MedlinePlus Encyclopedia: Hyperparathyroidism - MedlinePlus Encyclopedia: Medullary Carcinoma of Thyroid - MedlinePlus Encyclopedia: Multiple Endocrine Neoplasia (MEN) I - MedlinePlus Encyclopedia: Multiple Endocrine Neoplasia (MEN) II - MedlinePlus Encyclopedia: Pancreatic Islet Cell Tumor - MedlinePlus Encyclopedia: Pheochromocytoma - MedlinePlus Encyclopedia: Pituitary Tumor - National Cancer Institute: Genetic Testing for Hereditary Cancer Syndromes - New York Thyroid Center: Medullary Thyroid Cancer 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) isovaleric acidemia ? | Isovaleric acidemia is a rare disorder in which the body is unable to process certain proteins properly. It is classified as an organic acid disorder, which is a condition that leads to an abnormal buildup of particular acids known as organic acids. Abnormal levels of organic acids in the blood (organic acidemia), urine (organic aciduria), and tissues can be toxic and can cause serious health problems. Normally, the body breaks down proteins from food into smaller parts called amino acids. Amino acids can be further processed to provide energy for growth and development. People with isovaleric acidemia have inadequate levels of an enzyme that helps break down a particular amino acid called leucine. Health problems related to isovaleric acidemia range from very mild to life-threatening. In severe cases, the features of isovaleric acidemia become apparent within a few days after birth. The initial symptoms include poor feeding, vomiting, seizures, and lack of energy (lethargy). These symptoms sometimes progress to more serious medical problems, including seizures, coma, and possibly death. A characteristic sign of isovaleric acidemia is a distinctive odor of sweaty feet during acute illness. This odor is caused by the buildup of a compound called isovaleric acid in affected individuals. In other cases, the signs and symptoms of isovaleric acidemia appear during childhood and may come and go over time. Children with this condition may fail to gain weight and grow at the expected rate (failure to thrive) and often have delayed development. In these children, episodes of more serious health problems can be triggered by prolonged periods without food (fasting), infections, or eating an increased amount of protein-rich foods. Some people with gene mutations that cause isovaleric acidemia are asymptomatic, which means they never experience any signs or symptoms of the condition. |
frequency | How many people are affected by isovaleric acidemia ? | Isovaleric acidemia is estimated to affect at least 1 in 250,000 people in the United States. |
genetic changes | What are the genetic changes related to isovaleric acidemia ? | Mutations in the IVD gene cause isovaleric acidemia. The IVD gene provides instructions for making an enzyme that plays an essential role in breaking down proteins from the diet. Specifically, this enzyme helps process the amino acid leucine, which is part of many proteins. If a mutation in the IVD gene reduces or eliminates the activity of this enzyme, the body is unable to break down leucine properly. As a result, an organic acid called isovaleric acid and related compounds build up to harmful levels in the body. This buildup damages the brain and nervous system, causing serious health problems. |
inheritance | Is isovaleric acidemia 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 isovaleric acidemia ? | These resources address the diagnosis or management of isovaleric acidemia: - Baby's First Test - Genetic Testing Registry: Isovaleryl-CoA dehydrogenase deficiency 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) activated PI3K-delta syndrome ? | Activated PI3K-delta syndrome is a disorder that impairs the immune system. Individuals with this condition often have low numbers of white blood cells (lymphopenia), particularly B cells and T cells. Normally, these cells recognize and attack foreign invaders, such as viruses and bacteria, to prevent infection. Beginning in childhood, people with activated PI3K-delta syndrome develop recurrent infections, particularly in the lungs, sinuses, and ears. Over time, recurrent respiratory tract infections can lead to a condition called bronchiectasis, which damages the passages leading from the windpipe to the lungs (bronchi) and can cause breathing problems. People with activated PI3K-delta syndrome may also have chronic active viral infections, commonly Epstein-Barr virus or cytomegalovirus infections. Another possible feature of activated PI3K-delta syndrome is abnormal clumping of white blood cells. These clumps can lead to enlarged lymph nodes (lymphadenopathy), or the white blood cells can build up to form solid masses (nodular lymphoid hyperplasia), usually in the moist lining of the airways or intestines. While lymphadenopathy and nodular lymphoid hyperplasia are noncancerous (benign), activated PI3K-delta syndrome also increases the risk of developing a form of cancer called B-cell lymphoma. |
frequency | How many people are affected by activated PI3K-delta syndrome ? | The prevalence of activated PI3K-delta syndrome is unknown. |
genetic changes | What are the genetic changes related to activated PI3K-delta syndrome ? | Activated PI3K-delta syndrome is caused by mutations in the PIK3CD gene, which provides instructions for making a protein called p110 delta (p110). This protein is one piece (subunit) of an enzyme called phosphatidylinositol 3-kinase (PI3K), which turns on signaling pathways within cells. The version of PI3K containing the p110 subunit, called PI3K-delta, is specifically found in white blood cells, including B cells and T cells. PI3K-delta signaling is involved in the growth and division (proliferation) of white blood cells, and it helps direct B cells and T cells to mature (differentiate) into different types, each of which has a distinct function in the immune system. PIK3CD gene mutations involved in activated PI3K-delta syndrome lead to production of an altered p110 protein. A PI3K-delta enzyme containing the altered subunit is abnormally turned on (activated). Studies indicate that overactive PI3K-delta signaling alters the differentiation of B cells and T cells, leading to production of cells that cannot respond to infections and that die earlier than usual. Lack of functioning B cells and T cells makes it difficult for people with this disorder to fight off bacterial and viral infections. Overactivation of PI3K-delta signaling can also stimulate abnormal proliferation of white blood cells, leading to lymphadenopathy and nodular lymphoid hyperplasia in some affected individuals. An increase in B cell proliferation in combination with reduced immune system function may contribute to development of B-cell lymphoma. |
inheritance | Is activated PI3K-delta 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. |
treatment | What are the treatments for activated PI3K-delta syndrome ? | These resources address the diagnosis or management of activated PI3K-delta syndrome: - Genetic Testing Registry: Activated PI3K-delta syndrome - National Institute of Allergy and Infectious Diseases: Primary Immune Deficiency Diseases: Talking To Your Doctor 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) mucopolysaccharidosis type II ? | Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a condition that affects many different parts of the body and occurs almost exclusively in males. It is a progressively debilitating disorder; however, the rate of progression varies among affected individuals. At birth, individuals with MPS II do not display any features of the condition. Between ages 2 and 4, they develop full lips, large rounded cheeks, a broad nose, and an enlarged tongue (macroglossia). The vocal cords also enlarge, which results in a deep, hoarse voice. Narrowing of the airway causes frequent upper respiratory infections and short pauses in breathing during sleep (sleep apnea). As the disorder progresses, individuals need medical assistance to keep their airway open. Many other organs and tissues are affected in MPS II. Individuals with this disorder often have a large head (macrocephaly), a buildup of fluid in the brain (hydrocephalus), an enlarged liver and spleen (hepatosplenomegaly), and a soft out-pouching around the belly-button (umbilical hernia) or lower abdomen (inguinal hernia). People with MPS II usually have thick skin that is not very stretchy. Some affected individuals also have distinctive white skin growths that look like pebbles. Most people with this disorder develop hearing loss and have recurrent ear infections. Some individuals with MPS II develop problems with the light-sensitive tissue in the back of the eye (retina) and have reduced vision. Carpal tunnel syndrome commonly occurs in children with this disorder and is characterized by numbness, tingling, and weakness in the hand and fingers. Narrowing of the spinal canal (spinal stenosis) in the neck can compress and damage the spinal cord. The heart is also significantly affected by MPS II, and many individuals develop heart valve problems. Heart valve abnormalities can cause the heart to become enlarged (ventricular hypertrophy) and can eventually lead to heart failure. Children with MPS II grow steadily until about age 5, and then their growth slows and they develop short stature. Individuals with this condition have joint deformities (contractures) that significantly affect mobility. Most people with MPS II also have dysostosis multiplex, which refers to multiple skeletal abnormalities seen on x-ray. Dysostosis multiplex includes a generalized thickening of most long bones, particularly the ribs. There are two types of MPS II, called the severe and mild types. While both types affect many different organs and tissues as described above, people with severe MPS II also experience a decline in intellectual function and a more rapid disease progression. Individuals with the severe form begin to lose basic functional skills (developmentally regress) between the ages of 6 and 8. The life expectancy of these individuals is 10 to 20 years. Individuals with mild MPS II also have a shortened lifespan, but they typically live into adulthood and their intelligence is not affected. Heart disease and airway obstruction are major causes of death in people with both types of MPS II. |
frequency | How many people are affected by mucopolysaccharidosis type II ? | MPS II occurs in approximately 1 in 100,000 to 1 in 170,000 males. |
genetic changes | What are the genetic changes related to mucopolysaccharidosis type II ? | Mutations in the IDS gene cause MPS II. The IDS gene provides instructions for producing the I2S enzyme, which is involved in the breakdown of large sugar molecules called glycosaminoglycans (GAGs). GAGs were originally called mucopolysaccharides, which is where this condition gets its name. Mutations in the IDS gene reduce or completely eliminate the function of the I2S enzyme. Lack of I2S enzyme activity leads to the accumulation of GAGs within cells, specifically inside the lysosomes. Lysosomes are compartments in the cell that digest and recycle different types of molecules. Conditions that cause molecules to build up inside the lysosomes, including MPS II, are called lysosomal storage disorders. The accumulation of GAGs increases the size of the lysosomes, which is why many tissues and organs are enlarged in this disorder. Researchers believe that the GAGs may also interfere with the functions of other proteins inside the lysosomes and disrupt the movement of molecules inside the cell. |
inheritance | Is mucopolysaccharidosis type II inherited ? | This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. |
treatment | What are the treatments for mucopolysaccharidosis type II ? | These resources address the diagnosis or management of mucopolysaccharidosis type II: - Baby's First Test - Gene Review: Gene Review: Mucopolysaccharidosis Type II - Genetic Testing Registry: Mucopolysaccharidosis, MPS-II - MedlinePlus Encyclopedia: Hunter syndrome - MedlinePlus Encyclopedia: Mucopolysaccharides 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) fish-eye disease ? | Fish-eye disease, also called partial LCAT deficiency, is a disorder that causes the clear front surface of the eyes (the corneas) to gradually become cloudy. The cloudiness, which generally first appears in adolescence or early adulthood, consists of small grayish dots of cholesterol (opacities) distributed across the corneas. Cholesterol is a waxy, fat-like substance that is produced in the body and obtained from foods that come from animals; it aids in many functions of the body but can become harmful in excessive amounts. As fish-eye disease progresses, the corneal cloudiness worsens and can lead to severely impaired vision. |
frequency | How many people are affected by fish-eye disease ? | Fish-eye disease is a rare disorder. Approximately 30 cases have been reported in the medical literature. |
genetic changes | What are the genetic changes related to fish-eye disease ? | Fish-eye disease is caused by mutations in the LCAT gene. This gene provides instructions for making an enzyme called lecithin-cholesterol acyltransferase (LCAT). The LCAT enzyme plays a role in removing cholesterol from the blood and tissues by helping it attach to molecules called lipoproteins, which carry it to the liver. Once in the liver, the cholesterol is redistributed to other tissues or removed from the body. The enzyme has two major functions, called alpha- and beta-LCAT activity. Alpha-LCAT activity helps attach cholesterol to a lipoprotein called high-density lipoprotein (HDL). Beta-LCAT activity helps attach cholesterol to other lipoproteins called very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL). LCAT gene mutations that cause fish-eye disease impair alpha-LCAT activity, reducing the enzyme's ability to attach cholesterol to HDL. Impairment of this mechanism for reducing cholesterol in the body leads to cholesterol-containing opacities in the corneas. It is not known why the cholesterol deposits affect only the corneas in this disorder. Mutations that affect both alpha-LCAT activity and beta-LCAT activity lead to a related disorder called complete LCAT deficiency, which involves corneal opacities in combination with features affecting other parts of the body. |
inheritance | Is fish-eye 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 fish-eye disease ? | These resources address the diagnosis or management of fish-eye disease: - Genetic Testing Registry: Fish-eye disease - MedlinePlus Encyclopedia: Corneal Transplant - Oregon Health and Science University: Corneal Dystrophy 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) factor V deficiency ? | Factor V deficiency is a rare bleeding disorder. The signs and symptoms of this condition can begin at any age, although the most severe cases are apparent in childhood. Factor V deficiency commonly causes nosebleeds; easy bruising; bleeding under the skin; bleeding of the gums; and prolonged or excessive bleeding following surgery, trauma, or childbirth. Women with factor V deficiency can have heavy or prolonged menstrual bleeding (menorrhagia). Bleeding into joint spaces (hemarthrosis) can also occur, although it is rare. Severely affected individuals have an increased risk of bleeding inside the skull (intracranial hemorrhage), in the lungs (pulmonary hemorrhage), or in the gastrointestinal tract, which can be life-threatening. |
frequency | How many people are affected by factor V deficiency ? | Factor V deficiency affects an estimated 1 in 1 million people. This condition is more common in countries such as Iran and southern India, where it occurs up to ten times more frequently than in western countries. |
genetic changes | What are the genetic changes related to factor V deficiency ? | Factor V deficiency is usually caused by mutations in the F5 gene, which provides instructions for making a protein called coagulation factor V. This protein plays a critical role in the coagulation system, which is a series of chemical reactions that forms blood clots in response to injury. F5 gene mutations that cause factor V deficiency prevent the production of functional coagulation factor V or severely reduce the amount of the protein in the bloodstream. People with this condition typically have less than 10 percent of normal levels of coagulation factor V in their blood; the most severely affected individuals have less than 1 percent. A reduced amount of functional coagulation factor V prevents blood from clotting normally, causing episodes of abnormal bleeding that can be severe. Very rarely, a form of factor V deficiency is caused by abnormal antibodies that recognize coagulation factor V. Antibodies normally attach (bind) to specific foreign particles and germs, marking them for destruction, but the antibodies in this form of factor V deficiency attack a normal human protein, leading to its inactivation. These cases are called acquired factor V deficiency and usually occur in individuals who have been treated with substances that stimulate the production of anti-factor V antibodies, such as bovine thrombin used during surgical procedures. There is no known genetic cause for this form of the condition. |
inheritance | Is factor V deficiency inherited ? | Factor V deficiency is inherited in an autosomal recessive pattern, which means both copies of the F5 gene in each cell have mutations. Individuals with a mutation in a single copy of the F5 gene have a reduced amount of coagulation factor V in their blood and can have mild bleeding problems, although most have no related health effects. |
treatment | What are the treatments for factor V deficiency ? | These resources address the diagnosis or management of factor V deficiency: - Genetic Testing Registry: Factor V deficiency - MedlinePlus Encyclopedia: Factor V Deficiency 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) X-linked chondrodysplasia punctata 2 ? | X-linked chondrodysplasia punctata 2 is a disorder characterized by bone, skin, and eye abnormalities. It occurs almost exclusively in females. Although the signs and symptoms of this condition vary widely, almost all affected individuals have chondrodysplasia punctata, an abnormality that appears on x-rays as spots (stippling) near the ends of bones and in cartilage. In this form of chondrodysplasia punctata, the stippling typically affects the long bones in the arms and legs, the ribs, the spinal bones (vertebrae), and the cartilage that makes up the windpipe (trachea). The stippling is apparent in infancy but disappears in early childhood. Other skeletal abnormalities seen in people with X-linked chondrodysplasia punctata 2 include shortening of the bones in the upper arms and thighs (rhizomelia) that is often different on the right and left sides, and progressive abnormal curvature of the spine (kyphoscoliosis). As a result of these abnormalities, people with this condition tend to have short stature. Infants with X-linked chondrodysplasia punctata 2 are born with dry, scaly patches of skin (ichthyosis) in a linear or spiral (whorled) pattern. The scaly patches fade over time, leaving abnormally colored blotches of skin without hair (follicular atrophoderma). Most affected individuals also have sparse, coarse hair on their scalps. Most people with X-linked chondrodysplasia punctata 2 have clouding of the lens of the eye (cataracts) from birth or early childhood. Other eye abnormalities that have been associated with this disorder include unusually small eyes (microphthalmia) and small corneas (microcornea). The cornea is the clear front surface of the eye. These eye abnormalities can impair vision. In affected females, X-linked chondrodysplasia punctata 2 is typically associated with normal intelligence and a normal lifespan. However, a much more severe form of the condition has been reported in a small number of males. Affected males have some of the same features as affected females, as well as weak muscle tone (hypotonia), changes in the structure of the brain, moderately to profoundly delayed development, seizures, distinctive facial features, and other birth defects. The health problems associated with X-linked chondrodysplasia punctata 2 are often life-threatening in males. |
frequency | How many people are affected by X-linked chondrodysplasia punctata 2 ? | X-linked chondrodysplasia punctata 2 has been estimated to affect fewer than 1 in 400,000 newborns. However, the disorder may actually be more common than this estimate because it is likely underdiagnosed, particularly in females with mild signs and symptoms. More than 95 percent of cases of X-linked chondrodysplasia punctata 2 occur in females. About a dozen males with the condition have been reported in the scientific literature. |
genetic changes | What are the genetic changes related to X-linked chondrodysplasia punctata 2 ? | X-linked chondrodysplasia punctata 2 is caused by mutations in the EBP gene. This gene provides instructions for making an enzyme called 3-hydroxysteroid-8,7-isomerase, which is responsible for one of the final steps in the production of cholesterol. Cholesterol is a waxy, fat-like substance that is produced in the body and obtained from foods that come from animals (particularly egg yolks, meat, poultry, fish, and dairy products). Although too much cholesterol is a risk factor for heart disease, this molecule is necessary for normal embryonic development and has important functions both before and after birth. It is a structural component of cell membranes and plays a role in the production of certain hormones and digestive acids. Mutations in the EBP gene reduce the activity of 3-hydroxysteroid-8,7-isomerase, preventing cells from producing enough cholesterol. A shortage of this enzyme also allows potentially toxic byproducts of cholesterol production to build up in the body. The combination of low cholesterol levels and an accumulation of other substances likely disrupts the growth and development of many body systems. It is not known, however, how this disturbance in cholesterol production leads to the specific features of X-linked chondrodysplasia punctata 2. |
inheritance | Is X-linked chondrodysplasia punctata 2 inherited ? | This condition is inherited in an X-linked dominant pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In females (who have two X chromosomes), a mutation in one of the two copies of the EBP gene in each cell is sufficient to cause the disorder. Some cells produce a normal amount of 3-hydroxysteroid-8,7-isomerase and other cells produce none. The resulting overall reduction in the amount of this enzyme underlies the signs and symptoms of X-linked chondrodysplasia punctata 2. In males (who have only one X chromosome), a mutation in the EBP gene can result in a total loss of 3-hydroxysteroid-8,7-isomerase. A complete lack of this enzyme is usually lethal in the early stages of development, so few males have been born with X-linked chondrodysplasia punctata 2. |
treatment | What are the treatments for X-linked chondrodysplasia punctata 2 ? | These resources address the diagnosis or management of X-linked chondrodysplasia punctata 2: - Gene Review: Gene Review: Chondrodysplasia Punctata 2, X-Linked - Genetic Testing Registry: Chondrodysplasia punctata 2 X-linked 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) familial idiopathic basal ganglia calcification ? | Familial idiopathic basal ganglia calcification (FIBGC, formerly known as Fahr disease) is a condition characterized by abnormal deposits of calcium (calcification) in the brain. These calcium deposits typically occur in the basal ganglia, which are structures deep within the brain that help start and control movement; however, other brain regions can also be affected. The signs and symptoms of FIBGC include movement disorders and psychiatric or behavioral difficulties. These problems begin in adulthood, usually in a person's thirties. The movement difficulties experienced by people with FIBGC include involuntary tensing of various muscles (dystonia), problems coordinating movements (ataxia), and uncontrollable movements of the limbs (choreoathetosis). Affected individuals often have seizures as well. The psychiatric and behavioral problems include difficulty concentrating, memory loss, changes in personality, a distorted view of reality (psychosis), and decline in intellectual function (dementia). An estimated 20 to 30 percent of people with FIBGC have one of these psychiatric disorders. The severity of this condition varies among affected individuals; some people have no symptoms related to the brain calcification, whereas other people have significant movement and psychiatric problems. |
frequency | How many people are affected by familial idiopathic basal ganglia calcification ? | FIBGC is thought to be a rare disorder; about 60 affected families have been described in the medical literature. However, because brain imaging tests are needed to recognize the calcium deposits, this condition is believed to be underdiagnosed. |
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