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genetic changes | What are the genetic changes related to Brody myopathy ? | Mutations in the ATP2A1 gene cause Brody myopathy. The ATP2A1 gene provides instructions for making an enzyme called sarco(endo)plasmic reticulum calcium-ATPase 1 (SERCA1). The SERCA1 enzyme is found in skeletal muscle cells, specifically in the membrane of a structure called the sarcoplasmic reticulum. This structure plays a major role in muscle contraction and relaxation by storing and releasing positively charged calcium atoms (calcium ions). When calcium ions are transported out of the sarcoplasmic reticulum, muscles contract; when calcium ions are transported into the sarcoplasmic reticulum, muscles relax. The SERCA1 enzyme transports calcium ions from the cell into the sarcoplasmic reticulum, triggering muscle relaxation. ATP2A1 gene mutations lead to the production of a SERCA1 enzyme with decreased or no function. As a result, calcium ions are slow to enter the sarcoplasmic reticulum and muscle relaxation is delayed. After exercise or strenuous activity, during which the muscles rapidly contract and relax, people with Brody myopathy develop muscle cramps because their muscles cannot fully relax. |
inheritance | Is Brody myopathy inherited ? | Brody myopathy 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. Some people with autosomal recessive Brody myopathy do not have an identified mutation in the ATP2A1 gene; the cause of the disease in these individuals is unknown. |
treatment | What are the treatments for Brody myopathy ? | These resources address the diagnosis or management of Brody myopathy: - Genetic Testing Registry: Brody myopathy - New York Presbyterian Hospital: Myopathy 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) isolated lissencephaly sequence ? | Isolated lissencephaly sequence (ILS) is a condition that affects brain development before birth. Normally, the cells that make up the exterior of the brain (cerebral cortex) are well-organized, multi-layered, and arranged into many folds and grooves (gyri). In people with ILS, the cells of the cerebral cortex are disorganized, and the brain surface is abnormally smooth with an absence (agyria) or reduction (pachygyria) of folds and grooves. In most cases, these abnormalities impair brain growth, causing the brain to be smaller than normal (microcephaly). This underdevelopment of the brain causes severe intellectual disability, delayed development, and recurrent seizures (epilepsy) in individuals with ILS. More than 90 percent of individuals with ILS develop epilepsy, often within the first year of life. Up to 80 percent of infants with ILS have a type of seizure called infantile spasms, these seizures can be severe enough to cause brain dysfunction (epileptic encephalopathy). After the first months of life, most children with ILS develop a variety of seizure types, including persisting infantile spasms, short periods of loss of consciousness (absence seizures); sudden episodes of weak muscle tone (drop attacks); rapid, uncontrolled muscle jerks (myoclonic seizures); and episodes of muscle rigidity, convulsions, and loss of consciousness (tonic-clonic seizures). Infants with ILS may have poor muscle tone (hypotonia) and difficulty feeding, which leads to poor growth overall. Hypotonia also affects the muscles used for breathing, which often causes breathing problems that can lead to a life-threatening bacterial lung infection known as aspiration pneumonia. Children with ILS often develop muscle stiffness (spasticity) in their arms and legs and an abnormal side-to-side curvature of the spine (scoliosis). Rarely, the muscle stiffness will progress to paralysis (spastic paraplegia). Individuals with ILS cannot walk and rarely crawl. Most children with ILS do not develop communication skills. |
frequency | How many people are affected by isolated lissencephaly sequence ? | ILS affects approximately 1 in 100,000 newborns. |
genetic changes | What are the genetic changes related to isolated lissencephaly sequence ? | Mutations in the PAFAH1B1, DCX, or TUBA1A gene can cause ILS. PAFAH1B1 gene mutations are responsible for over half of ILS cases; DCX gene mutations cause about 10 percent of cases; and TUBA1A gene mutations cause a small percentage of ILS. These genes provide instructions for making proteins that are involved in the movement (migration) of nerve cells (neurons) to their proper locations in the developing brain. Neuronal migration is dependent on cell structures called microtubules. Microtubules are rigid, hollow fibers that make up the cell's structural framework (the cytoskeleton). Microtubules form scaffolding within the cell that elongates in a specific direction, altering the cytoskeleton and moving the neuron. The protein produced from the TUBA1A gene is a component of microtubules. The proteins produced from the DCX and PAFAH1B1 genes promote neuronal migration by interacting with microtubules. Mutations in any of these three genes impair the function of microtubules and the normal migration of neurons during fetal development. As a result, the layers of the cerebral cortex are disorganized and the normal folds and grooves of the brain do not form. This impairment of brain development leads to the smooth brain appearance and the resulting neurological problems characteristic of ILS. Some individuals with ILS do not have an identified mutation in any of these three genes; the cause of the condition in these individuals may be unidentified mutations in other genes that affect neuronal migration or other unknown factors. |
inheritance | Is isolated lissencephaly sequence inherited ? | The inheritance pattern of ILS depends on the gene involved. When ILS is caused by mutations in the PAFAH1B1 or TUBA1A gene, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases result from new mutations in the gene and occur in people with no history of the disorder in their family. When mutations in the DCX gene cause ILS, it is inherited in an X-linked 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 males (who have only one X chromosome), one altered copy of the DCX gene in each cell is sufficient to cause the condition. In females, who have two copies of the X chromosome, one altered copy of the DCX gene in each cell can lead to a less severe condition in females called subcortical band heterotopia, or may cause no symptoms at all. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. |
treatment | What are the treatments for isolated lissencephaly sequence ? | These resources address the diagnosis or management of isolated lissencephaly sequence: - Gene Review: Gene Review: DCX-Related Disorders - Gene Review: Gene Review: LIS1-Associated Lissencephaly/Subcortical Band Heterotopia - Gene Review: Gene Review: Tubulinopathies Overview - Genetic Testing Registry: Lissencephaly 1 - Genetic Testing Registry: Lissencephaly 3 - Genetic Testing Registry: Lissencephaly, X-linked 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) homocystinuria ? | Homocystinuria is an inherited disorder in which the body is unable to process certain building blocks of proteins (amino acids) properly. There are multiple forms of homocystinuria, which are distinguished by their signs and symptoms and genetic cause. The most common form of homocystinuria is characterized by nearsightedness (myopia), dislocation of the lens at the front of the eye, an increased risk of abnormal blood clotting, and brittle bones that are prone to fracture (osteoporosis) or other skeletal abnormalities. Some affected individuals also have developmental delay and learning problems. Less common forms of homocystinuria can cause intellectual disability, failure to grow and gain weight at the expected rate (failure to thrive), seizures, problems with movement, and a blood disorder called megaloblastic anemia. Megaloblastic anemia occurs when a person has a low number of red blood cells (anemia), and the remaining red blood cells are larger than normal (megaloblastic). The signs and symptoms of homocystinuria typically develop within the first year of life, although some mildly affected people may not develop features until later in childhood or adulthood. |
frequency | How many people are affected by homocystinuria ? | The most common form of homocystinuria affects at least 1 in 200,000 to 335,000 people worldwide. The disorder appears to be more common in some countries, such as Ireland (1 in 65,000), Germany (1 in 17,800), Norway (1 in 6,400), and Qatar (1 in 1,800). The rarer forms of homocystinuria each have a small number of cases reported in the scientific literature. |
genetic changes | What are the genetic changes related to homocystinuria ? | Mutations in the CBS, MTHFR, MTR, MTRR, and MMADHC genes cause homocystinuria. Mutations in the CBS gene cause the most common form of homocystinuria. The CBS gene provides instructions for producing an enzyme called cystathionine beta-synthase. This enzyme acts in a chemical pathway and is responsible for converting the amino acid homocysteine to a molecule called cystathionine. As a result of this pathway, other amino acids, including methionine, are produced. Mutations in the CBS gene disrupt the function of cystathionine beta-synthase, preventing homocysteine from being used properly. As a result, this amino acid and toxic byproducts substances build up in the blood. Some of the excess homocysteine is excreted in urine. Rarely, homocystinuria can be caused by mutations in several other genes. The enzymes made by the MTHFR, MTR, MTRR, and MMADHC genes play roles in converting homocysteine to methionine. Mutations in any of these genes prevent the enzymes from functioning properly, which leads to a buildup of homocysteine in the body. Researchers have not determined how excess homocysteine and related compounds lead to the signs and symptoms of homocystinuria. |
inheritance | Is homocystinuria inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition. Although people who carry one mutated copy and one normal copy of the CBS gene do not have homocystinuria, they are more likely than people without a CBS mutation to have shortages (deficiencies) of vitamin B12 and folic acid. |
treatment | What are the treatments for homocystinuria ? | These resources address the diagnosis or management of homocystinuria: - Baby's First Test - Gene Review: Gene Review: Disorders of Intracellular Cobalamin Metabolism - Gene Review: Gene Review: Homocystinuria Caused by Cystathionine Beta-Synthase Deficiency - Genetic Testing Registry: Homocysteinemia due to MTHFR deficiency - Genetic Testing Registry: Homocystinuria due to CBS deficiency - Genetic Testing Registry: Homocystinuria, cblD type, variant 1 - Genetic Testing Registry: Homocystinuria-Megaloblastic anemia due to defect in cobalamin metabolism, cblE complementation type - Genetic Testing Registry: METHYLCOBALAMIN DEFICIENCY, cblG TYPE - Genetic Testing Registry: Methylmalonic acidemia with homocystinuria cblD - Genetic Testing Registry: Methylmalonic aciduria, cblD type, variant 2 - MedlinePlus Encyclopedia: Homocystinuria - New England Consortium of Metabolic Programs 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 congenital stationary night blindness ? | X-linked congenital stationary night blindness is a disorder of the retina, which is the specialized tissue at the back of the eye that detects light and color. People with this condition typically have difficulty seeing in low light (night blindness). They also have other vision problems, including loss of sharpness (reduced acuity), severe nearsightedness (high myopia), involuntary movements of the eyes (nystagmus), and eyes that do not look in the same direction (strabismus). Color vision is typically not affected by this disorder. The vision problems associated with this condition are congenital, which means they are present from birth. They tend to remain stable (stationary) over time. Researchers have identified two major types of X-linked congenital stationary night blindness: the complete form and the incomplete form. The types have very similar signs and symptoms. However, everyone with the complete form has night blindness, while not all people with the incomplete form have night blindness. The types are distinguished by their genetic cause and by the results of a test called an electroretinogram, which measures the function of the retina. |
frequency | How many people are affected by X-linked congenital stationary night blindness ? | The prevalence of this condition is unknown. It appears to be more common in people of Dutch-German Mennonite descent. However, this disorder has been reported in families with many different ethnic backgrounds. The incomplete form is more common than the complete form. |
genetic changes | What are the genetic changes related to X-linked congenital stationary night blindness ? | Mutations in the NYX and CACNA1F genes cause the complete and incomplete forms of X-linked congenital stationary night blindness, respectively. The proteins produced from these genes play critical roles in the retina. Within the retina, the NYX and CACNA1F proteins are located on the surface of light-detecting cells called photoreceptors. The retina contains two types of photoreceptor cells: rods and cones. Rods are needed for vision in low light. Cones are needed for vision in bright light, including color vision. The NYX and CACNA1F proteins ensure that visual signals are passed from rods and cones to other retinal cells called bipolar cells, which is an essential step in the transmission of visual information from the eyes to the brain. Mutations in the NYX or CACNA1F gene disrupt the transmission of visual signals between photoreceptors and retinal bipolar cells, which impairs vision. In people with the complete form of X-linked congenital stationary night blindness (resulting from NYX mutations), the function of rods is severely disrupted, while the function of cones is only mildly affected. In people with the incomplete form of the condition (resulting from CACNA1F mutations), rods and cones are both affected, although they retain some ability to detect light. |
inheritance | Is X-linked congenital stationary night blindness inherited ? | This condition is inherited in an X-linked recessive pattern. The NYX and CACNA1F genes 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. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons. In X-linked recessive inheritance, a female with one altered copy of the gene in each cell is called a carrier. Carriers of an NYX or CACNA1F mutation can pass on the mutated gene, but most do not develop any of the vision problems associated with X-linked congenital stationary night blindness. However, carriers may have retinal changes that can be detected with an electroretinogram. |
treatment | What are the treatments for X-linked congenital stationary night blindness ? | These resources address the diagnosis or management of X-linked congenital stationary night blindness: - American Optometric Association: Infant Vision - Gene Review: Gene Review: X-Linked Congenital Stationary Night Blindness - Genetic Testing Registry: Congenital stationary night blindness - Genetic Testing Registry: Congenital stationary night blindness, type 1A - Genetic Testing Registry: Congenital stationary night blindness, type 2A - MedlinePlus Encyclopedia: Electroretinography - MedlinePlus Encyclopedia: Eye movements - Uncontrollable - MedlinePlus Encyclopedia: Nearsightedness - MedlinePlus Encyclopedia: Strabismus - MedlinePlus Encyclopedia: Vision - Night Blindness 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) cytogenetically normal acute myeloid leukemia ? | Cytogenetically normal acute myeloid leukemia (CN-AML) is one form of a cancer of the blood-forming tissue (bone marrow) called acute myeloid leukemia. In normal bone marrow, early blood cells called hematopoietic stem cells develop into several types of blood cells: white blood cells (leukocytes) that protect the body from infection, red blood cells (erythrocytes) that carry oxygen, and platelets (thrombocytes) that are involved in blood clotting. In acute myeloid leukemia, the bone marrow makes large numbers of abnormal, immature white blood cells called myeloid blasts. Instead of developing into normal white blood cells, the myeloid blasts develop into cancerous leukemia cells. The large number of abnormal cells in the bone marrow interferes with the production of functional white blood cells, red blood cells, and platelets. People with CN-AML have a shortage of all types of mature blood cells: a shortage of white blood cells (leukopenia) leads to increased susceptibility to infections, a low number of red blood cells (anemia) causes fatigue and weakness, and a reduction in the amount of platelets (thrombocytopenia) can result in easy bruising and abnormal bleeding. Other symptoms of CN-AML may include fever and weight loss. The age at which CN-AML begins ranges from childhood to late adulthood. CN-AML is said to be an intermediate-risk cancer because the prognosis varies: some affected individuals respond well to normal treatment while others may require stronger treatments. The age at which the condition begins and the prognosis are affected by the specific genetic factors involved in the condition. |
frequency | How many people are affected by cytogenetically normal acute myeloid leukemia ? | Acute myeloid leukemia occurs in approximately 3.5 per 100,000 individuals each year. Forty to 50 percent of people with acute myeloid leukemia have CN-AML. |
genetic changes | What are the genetic changes related to cytogenetically normal acute myeloid leukemia ? | CN-AML is classified as "cytogenetically normal" based on the type of genetic changes involved in its development. Cytogenetically normal refers to the fact that this form of acute myeloid leukemia is not associated with large chromosomal abnormalities. About half of people with acute myeloid leukemia have this form of the condition; the other half have genetic changes that alter large regions of certain chromosomes. These changes can be identified by a test known as cytogenetic analysis. CN-AML is associated with smaller genetic changes that cannot be seen by cytogenetic analysis. Mutations in a large number of genes have been found in people with CN-AML; the most commonly affected genes are NPM1, FLT3, DNMT3A, CEBPA, IDH1, and IDH2. The proteins produced from these genes have different functions in the cell. Most are involved in regulating processes such as the growth and division (proliferation), maturation (differentiation), or survival of cells. For example, the protein produced from the FLT3 gene stimulates the proliferation and survival of cells. The proteins produced from the CEBPA and DNMT3A genes regulate gene activity and help to control when cells divide and how they mature. The NPM1 gene provides instructions for a protein that is likely involved in the regulation of cell growth and division. Mutations in any of these genes can disrupt one or more of these processes in hematopoietic stem cells and lead to overproduction of abnormal, immature white blood cells, which is characteristic of CN-AML. Although the proteins produced from two other genes involved in CN-AML, IDH1 and IDH2, are not normally involved in proliferation, differentiation, or survival of cells, mutations in these genes lead to the production of proteins with a new function. These changes result in impaired differentiation of hematopoietic stem cells, which leads to CN-AML. CN-AML is a complex condition influenced by several genetic and environmental factors. Typically, mutations in more than one gene are involved. For example, people with an NPM1 gene mutation frequently also have a mutation in the FLT3 gene, both of which are likely involved in the cancer's development. In addition, environmental factors such as smoking or exposure to radiation increase an individual's risk of developing acute myeloid leukemia. |
inheritance | Is cytogenetically normal acute myeloid leukemia inherited ? | CN-AML is not usually inherited but arises from genetic changes in the body's cells that occur after conception. Rarely, an inherited mutation in the CEBPA gene causes acute myeloid leukemia. In these cases, the condition follows an autosomal dominant pattern of inheritance, which means that one copy of the altered CEBPA gene in each cell is sufficient to cause the disorder. These cases of CN-AML are referred to as familial acute myeloid leukemia with mutated CEBPA. |
treatment | What are the treatments for cytogenetically normal acute myeloid leukemia ? | These resources address the diagnosis or management of cytogenetically normal acute myeloid leukemia: - Fred Hutchinson Cancer Research Center - National Cancer Institute: Acute Myeloid Leukemia Treatment - St. Jude Children's Research Hospital 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) adermatoglyphia ? | Adermatoglyphia is the absence of ridges on the skin on the pads of the fingers and toes, as well as on the palms of the hands and soles of the feet. The patterns of these ridges (called dermatoglyphs) form whorls, arches, and loops that are the basis for each person's unique fingerprints. Because no two people have the same patterns, fingerprints have long been used as a way to identify individuals. However, people with adermatoglyphia do not have these ridges, and so they cannot be identified by their fingerprints. Adermatoglyphia has been called the "immigration delay disease" because affected individuals have had difficulty entering countries that require fingerprinting for identification. In some families, adermatoglyphia occurs without any related signs and symptoms. In others, a lack of dermatoglyphs is associated with other features, typically affecting the skin. These can include small white bumps called milia on the face, blistering of the skin in areas exposed to heat or friction, and a reduced number of sweat glands on the hands and feet. Adermatoglyphia is also a feature of several rare syndromes classified as ectodermal dysplasias, including a condition called Naegeli-Franceschetti-Jadassohn syndrome/dermatopathia pigmentosa reticularis that affects the skin, hair, sweat glands, and teeth. |
frequency | How many people are affected by adermatoglyphia ? | Adermatoglyphia appears to be a rare condition. Only a few affected families have been identified worldwide. |
genetic changes | What are the genetic changes related to adermatoglyphia ? | Adermatoglyphia is caused by mutations in the SMARCAD1 gene. This gene provides information for making two versions of the SMARCAD1 protein: a full-length version that is active (expressed) in multiple tissues and a shorter version that is expressed only in the skin. Studies suggest that the full-length SMARCAD1 protein regulates the activity of a wide variety of genes involved in maintaining the stability of cells' genetic information. Little is known about the function of the skin-specific version of the SMARCAD1 protein, but it appears to play a critical role in dermatoglyph formation. Dermatoglyphs develop before birth and remain the same throughout life. The activity of this protein is likely one of several factors that determine each person's unique fingerprint pattern. The SMARCAD1 gene mutations that cause adermatoglyphia affect only the skin-specific version of the SMARCAD1 protein. These mutations reduce the total amount of this protein available in skin cells. Although it is unclear how these genetic changes cause adermatoglyphia, researchers speculate that a shortage of the skin-specific version of the SMARCAD1 protein impairs signaling pathways needed for normal skin development and function, including the formation of dermatoglyphs. |
inheritance | Is adermatoglyphia inherited ? | Adermatoglyphia is inherited in an autosomal dominant pattern, which means one copy of the altered SMARCAD1 gene in each cell is sufficient to cause the condition. In many cases, an affected person has one parent with the condition. |
treatment | What are the treatments for adermatoglyphia ? | These resources address the diagnosis or management of adermatoglyphia: - Genetic Testing Registry: Adermatoglyphia 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 lissencephaly with abnormal genitalia ? | X-linked lissencephaly with abnormal genitalia (XLAG) is a condition that affects the development of the brain and genitalia. It occurs most often in males. XLAG is characterized by abnormal brain development that results in the brain having a smooth appearance (lissencephaly) instead of its normal folds and grooves. Individuals without any folds in the brain (agyria) typically have more severe symptoms than people with reduced folds and grooves (pachygyria). Individuals with XLAG may also have a lack of development (agenesis) of the tissue connecting the left and right halves of the brain (corpus callosum). The brain abnormalities can cause severe intellectual disability and developmental delay, abnormal muscle stiffness (spasticity), weak muscle tone (hypotonia), and feeding difficulties. Starting soon after birth, babies with XLAG have frequent and recurrent seizures (epilepsy). Most children with XLAG do not survive past early childhood. Another key feature of XLAG in males is abnormal genitalia that can include an unusually small penis (micropenis), undescended testes (cryptorchidism), or external genitalia that do not look clearly male or clearly female (ambiguous genitalia). Additional signs and symptoms of XLAG include chronic diarrhea, periods of increased blood sugar (transient hyperglycemia), and problems with body temperature regulation. |
frequency | How many people are affected by X-linked lissencephaly with abnormal genitalia ? | The incidence of XLAG is unknown; approximately 30 affected families have been described in the medical literature. |
genetic changes | What are the genetic changes related to X-linked lissencephaly with abnormal genitalia ? | Mutations in the ARX gene cause XLAG. The ARX gene provides instructions for producing a protein that is involved in the development of several organs, including the brain, testes, and pancreas. In the developing brain, the ARX protein is involved with movement and communication in nerve cells (neurons). The ARX protein regulates genes that play a role in the migration of specialized neurons (interneurons) to their proper location. Interneurons relay signals between neurons. In the pancreas and testes, the ARX protein helps to regulate the process by which cells mature to carry out specific functions (differentiation). ARX gene mutations lead to the production of a nonfunctional ARX protein or to the complete absence of ARX protein. As a result, the ARX protein cannot perform its role regulating the activity of genes important for interneuron migration. In addition to impairing normal brain development, a lack of functional ARX protein disrupts cell differentiation during the formation of the testes, leading to abnormal genitalia. It is thought that the disruption of ARX protein function in the pancreas plays a role in the chronic diarrhea and hyperglycemia experienced by individuals with XLAG. |
inheritance | Is X-linked lissencephaly with abnormal genitalia inherited ? | This condition is inherited in an X-linked 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 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 copies of the X chromosome, one altered copy of the gene in each cell can lead to less severe brain malformations or may cause no symptoms at all. 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 lissencephaly with abnormal genitalia ? | These resources address the diagnosis or management of X-linked lissencephaly with abnormal genitalia: - Genetic Testing Registry: Lissencephaly 2, X-linked 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) prothrombin thrombophilia ? | Prothrombin thrombophilia is an inherited disorder of blood clotting. Thrombophilia is an increased tendency to form abnormal blood clots in blood vessels. People who have prothrombin thrombophilia are at somewhat higher than average risk for a type of clot called a deep venous thrombosis, which typically occurs in the deep veins of the legs. Affected people also have an increased risk of developing a pulmonary embolism, which is a clot that travels through the bloodstream and lodges in the lungs. Most people with prothrombin thrombophilia never develop abnormal blood clots, however. Some research suggests that prothrombin thrombophilia is associated with a somewhat increased risk of pregnancy loss (miscarriage) and may also increase the risk of other complications during pregnancy. These complications may include pregnancy-induced high blood pressure (preeclampsia), slow fetal growth, and early separation of the placenta from the uterine wall (placental abruption). It is important to note, however, that most women with prothrombin thrombophilia have normal pregnancies. |
frequency | How many people are affected by prothrombin thrombophilia ? | Prothrombin thrombophilia is the second most common inherited form of thrombophilia after factor V Leiden thrombophilia. Approximately 1 in 50 people in the white population in the United States and Europe has prothrombin thrombophilia. This condition is less common in other ethnic groups, occurring in less than one percent of African American, Native American, or Asian populations. |
genetic changes | What are the genetic changes related to prothrombin thrombophilia ? | Prothrombin thrombophilia is caused by a particular mutation in the F2 gene. The F2 gene plays a critical role in the formation of blood clots in response to injury. The protein produced from the F2 gene, prothrombin (also called coagulation factor II), is the precursor to a protein called thrombin that initiates a series of chemical reactions in order to form a blood clot. The particular mutation that causes prothrombin thrombophilia results in an overactive F2 gene that causes too much prothrombin to be produced. An abundance of prothrombin leads to more thrombin, which promotes the formation of blood clots. Other factors also increase the risk of blood clots in people with prothrombin thrombophilia. These factors include increasing age, obesity, trauma, surgery, smoking, the use of oral contraceptives (birth control pills) or hormone replacement therapy, and pregnancy. The combination of prothrombin thrombophilia and mutations in other genes involved in blood clotting can also influence risk. |
inheritance | Is prothrombin thrombophilia inherited ? | The risk of developing an abnormal clot in a blood vessel depends on whether a person inherits one or two copies of the F2 gene mutation that causes prothrombin thrombophilia. In the general population, the risk of developing an abnormal blood clot is about 1 in 1,000 people per year. Inheriting one copy of the F2 gene mutation increases that risk to 2 to 3 in 1,000. People who inherit two copies of the mutation, one from each parent, may have a risk as high as 20 in 1,000. |
treatment | What are the treatments for prothrombin thrombophilia ? | These resources address the diagnosis or management of prothrombin thrombophilia: - Gene Review: Gene Review: Prothrombin-Related Thrombophilia - Genetic Testing Registry: Thrombophilia - MedlinePlus Encyclopedia: Deep venous thrombosis - MedlinePlus Encyclopedia: Pulmonary embolus 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) catecholaminergic polymorphic ventricular tachycardia ? | Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a condition characterized by an abnormal heart rhythm (arrhythmia). As the heart rate increases in response to physical activity or emotional stress, it can trigger an abnormally fast and irregular heartbeat called ventricular tachycardia. Episodes of ventricular tachycardia can cause light-headedness, dizziness, and fainting (syncope). In people with CPVT, these episodes typically begin in childhood. If CPVT is not recognized and treated, an episode of ventricular tachycardia may cause the heart to stop beating (cardiac arrest), leading to sudden death. Researchers suspect that CPVT may be a significant cause of sudden death in children and young adults without recognized heart abnormalities. |
frequency | How many people are affected by catecholaminergic polymorphic ventricular tachycardia ? | The prevalence of CPVT is estimated to be about 1 in 10,000 people. However, the true prevalence of this condition is unknown. |
genetic changes | What are the genetic changes related to catecholaminergic polymorphic ventricular tachycardia ? | CPVT can result from mutations in two genes, RYR2 and CASQ2. RYR2 gene mutations cause about half of all cases, while mutations in the CASQ2 gene account for 1 percent to 2 percent of cases. In people without an identified mutation in one of these genes, the genetic cause of the disorder is unknown. The RYR2 and CASQ2 genes provide instructions for making proteins that help maintain a regular heartbeat. For the heart to beat normally, heart muscle cells called myocytes must tense (contract) and relax in a coordinated way. Both the RYR2 and CASQ2 proteins are involved in handling calcium within myocytes, which is critical for the regular contraction of these cells. Mutations in either the RYR2 or CASQ2 gene disrupt the handling of calcium within myocytes. During exercise or emotional stress, impaired calcium regulation in the heart can lead to ventricular tachycardia in people with CPVT. |
inheritance | Is catecholaminergic polymorphic ventricular tachycardia inherited ? | When CPVT results from mutations in the RYR2 gene, it has an autosomal dominant pattern of inheritance. Autosomal dominant inheritance means that one copy of the altered gene in each cell is sufficient to cause the disorder. In about half of cases, an affected person inherits an RYR2 gene mutation from one affected parent. The remaining cases result from new mutations in the RYR2 gene and occur in people with no history of the disorder in their family. When CPVT is caused by mutations in the CASQ2 gene, the condition has an autosomal recessive pattern of inheritance. Autosomal recessive inheritance means that 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 catecholaminergic polymorphic ventricular tachycardia ? | These resources address the diagnosis or management of catecholaminergic polymorphic ventricular tachycardia: - Cleveland Clinic: Management of Arrhythmias - Gene Review: Gene Review: Catecholaminergic Polymorphic Ventricular Tachycardia - Genetic Testing Registry: Catecholaminergic polymorphic ventricular tachycardia - Genetic Testing Registry: Ventricular tachycardia, catecholaminergic polymorphic, 2 - MedlinePlus Encyclopedia: Fainting - MedlinePlus Encyclopedia: Ventricular Tachycardia 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) Schinzel-Giedion syndrome ? | Schinzel-Giedion syndrome is a severe condition that is apparent at birth and affects many body systems. Signs and symptoms of this condition include distinctive facial features, neurological problems, and organ and bone abnormalities. Because of their serious health problems, most affected individuals do not survive past childhood. Children with Schinzel-Giedion syndrome can have a variety of distinctive features. In most affected individuals, the middle of the face looks as though it has been drawn inward (midface retraction). Other facial features include a large or bulging forehead; wide-set eyes (ocular hypertelorism); a short, upturned nose; and a wide mouth with a large tongue (macroglossia). Affected individuals can have other distinctive features, including larger than normal gaps between the bones of the skull in infants (fontanelles), a short neck, ear malformations, an inability to secrete tears (alacrima), and excessive hairiness (hypertrichosis). Hypertrichosis often disappears in infancy. Children with Schinzel-Giedion syndrome have severe developmental delay. Other neurological problems can include severe feeding problems, seizures, or visual or hearing impairment. Affected individuals can also have abnormalities of organs such as the heart, kidneys, or genitals. Heart defects include problems with the heart valves, which control blood flow in the heart; the chambers of the heart that pump blood to the body (ventricles); or the dividing wall between the sides of the heart (the septum). Most children with Schinzel-Giedion syndrome have accumulation of urine in the kidneys (hydronephrosis), which can occur in one or both kidneys. Affected individuals can have genital abnormalities such as underdevelopment (hypoplasia) of the genitals. Affected boys may have the opening of the urethra on the underside of the penis (hypospadias). Bone abnormalities are common in people with Schinzel-Giedion syndrome. The bones at the base of the skull are often abnormally hard or thick (sclerotic), or the joint between the bones at the base of the skull (occipital synchondrosis) can be abnormally wide. In addition, affected individuals may have broad ribs, abnormal collarbones (clavicles), or shortened bones at the ends of the fingers (hypoplastic distal phalanges). Children with this condition who survive past infancy have a higher than normal risk of developing certain types of tumors called neuroepithelial tumors. |
frequency | How many people are affected by Schinzel-Giedion syndrome ? | Schinzel-Giedion syndrome is very rare, although the exact prevalence is unknown. |
genetic changes | What are the genetic changes related to Schinzel-Giedion syndrome ? | Schinzel-Giedion syndrome is caused by mutations in the SETBP1 gene. This gene provides instructions for making a protein called SET binding protein 1 (SETBP1), which is known to attach (bind) to another protein called SET. However, the function of the SETBP1 protein and the effect of its binding to the SET protein are unknown. The SETBP1 gene mutations that have been identified in Schinzel-Giedion syndrome cluster in one region of the gene known as exon 4. However, the effects of the mutations on the function of the gene or the protein are unknown. Researchers are working to understand how mutations in the SETBP1 gene cause the signs and symptoms of Schinzel-Giedion syndrome. |
inheritance | Is Schinzel-Giedion syndrome inherited ? | Schinzel-Giedion syndrome results from new mutations in the SETBP1 gene and occurs in people with no history of the disorder in their family. One copy of the altered gene in each cell is sufficient to cause the disorder. |
treatment | What are the treatments for Schinzel-Giedion syndrome ? | These resources address the diagnosis or management of Schinzel-Giedion syndrome: - Genetic Testing Registry: Schinzel-Giedion 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) PRICKLE1-related progressive myoclonus epilepsy with ataxia ? | PRICKLE1-related progressive myoclonus epilepsy with ataxia is a rare inherited condition characterized by recurrent seizures (epilepsy) and problems with movement. The signs and symptoms of this disorder usually begin between the ages of 5 and 10. Problems with balance and coordination (ataxia) are usually the first symptoms of PRICKLE1-related progressive myoclonus epilepsy with ataxia. Affected children often have trouble walking. Their gait is unbalanced and wide-based, and they may fall frequently. Later, children with this condition develop episodes of involuntary muscle jerking or twitching (myoclonus), which cause additional problems with movement. Myoclonus can also affect muscles in the face, leading to difficulty swallowing and slurred speech (dysarthria). Beginning later in childhood, some affected individuals develop tonic-clonic or grand mal seizures. These seizures involve a loss of consciousness, muscle rigidity, and convulsions. They often occur at night (nocturnally) while the person is sleeping. PRICKLE1-related progressive myoclonus epilepsy with ataxia does not seem to affect intellectual ability. Although a few affected individuals have died in childhood, many have lived into adulthood. |
frequency | How many people are affected by PRICKLE1-related progressive myoclonus epilepsy with ataxia ? | The prevalence of PRICKLE1-related progressive myoclonus epilepsy with ataxia is unknown. The condition has been reported in three large families from Jordan and northern Israel and in at least two unrelated individuals. |
genetic changes | What are the genetic changes related to PRICKLE1-related progressive myoclonus epilepsy with ataxia ? | PRICKLE1-related progressive myoclonus epilepsy with ataxia is caused by mutations in the PRICKLE1 gene. This gene provides instructions for making a protein called prickle homolog 1, whose function is unknown. Studies suggest that it interacts with other proteins that are critical for brain development and function. Mutations in the PRICKLE1 gene alter the structure of prickle homolog 1 and disrupt its ability to interact with other proteins. However, it is unclear how these changes lead to movement problems, seizures, and the other features of PRICKLE1-related progressive myoclonus epilepsy with ataxia. |
inheritance | Is PRICKLE1-related progressive myoclonus epilepsy with ataxia inherited ? | Some cases of PRICKLE1-related progressive myoclonus epilepsy with ataxia 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. Other cases of PRICKLE1-related progressive myoclonus epilepsy with ataxia are considered autosomal dominant because one copy of the altered gene in each cell is sufficient to cause the disorder. These cases result from new mutations in the gene and occur in people with no history of the disorder in their family. |
treatment | What are the treatments for PRICKLE1-related progressive myoclonus epilepsy with ataxia ? | These resources address the diagnosis or management of PRICKLE1-related progressive myoclonus epilepsy with ataxia: - Gene Review: Gene Review: PRICKLE1-Related Progressive Myoclonus Epilepsy with Ataxia - Genetic Testing Registry: Progressive myoclonus epilepsy with ataxia 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) autosomal dominant vitreoretinochoroidopathy ? | Autosomal dominant vitreoretinochoroidopathy (ADVIRC) is a disorder that affects several parts of the eyes, including the clear gel that fills the eye (the vitreous), the light-sensitive tissue that lines the back of the eye (the retina), and the network of blood vessels within the retina (the choroid). The eye abnormalities in ADVIRC can lead to varying degrees of vision impairment, from mild reduction to complete loss, although some people with the condition have normal vision. The signs and symptoms of ADVIRC vary, even among members of the same family. Many affected individuals have microcornea, in which the clear front covering of the eye (cornea) is small and abnormally curved. The area behind the cornea can also be abnormally small, which is described as a shallow anterior chamber. Individuals with ADVIRC can develop increased pressure in the eyes (glaucoma) or clouding of the lens of the eye (cataract). In addition, some people have breakdown (degeneration) of the vitreous or the choroid. A characteristic feature of ADVIRC, visible with a special eye exam, is a circular band of excess coloring (hyperpigmentation) in the retina. This feature can help physicians diagnose the disorder. Affected individuals may also have white spots on the retina. |
frequency | How many people are affected by autosomal dominant vitreoretinochoroidopathy ? | ADVIRC is considered a rare disease. Its prevalence is unknown. |
genetic changes | What are the genetic changes related to autosomal dominant vitreoretinochoroidopathy ? | ADVIRC is caused by mutations in the BEST1 gene. The protein produced from this gene, called bestrophin-1, is thought to play a critical role in normal vision. Bestrophin-1 is found in a thin layer of cells at the back of the eye called the retinal pigment epithelium. This cell layer supports and nourishes the retina and is involved in growth and development of the eye, maintenance of the retina, and the normal function of specialized cells called photoreceptors that detect light and color. In the retinal pigment epithelium, bestrophin-1 functions as a channel that transports charged chlorine atoms (chloride ions) across the cell membrane. Mutations in the BEST1 gene alter how the gene's instructions are used to make bestrophin-1, which leads to production of versions of the protein that are missing certain segments or have extra segments. It is not clear how these versions of bestrophin affect chloride ion transport or lead to the eye abnormalities characteristic of ADVIRC. Researchers suspect that the abnormalities are related to defects in the retinal pigment epithelium or the photoreceptors. |
inheritance | Is autosomal dominant vitreoretinochoroidopathy inherited ? | This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition. |
treatment | What are the treatments for autosomal dominant vitreoretinochoroidopathy ? | These resources address the diagnosis or management of autosomal dominant vitreoretinochoroidopathy: - American Foundation for the Blind: Living with Vision Loss - Genetic Testing Registry: Vitreoretinochoroidopathy 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) pyruvate carboxylase deficiency ? | Pyruvate carboxylase deficiency is an inherited disorder that causes lactic acid and other potentially toxic compounds to accumulate in the blood. High levels of these substances can damage the body's organs and tissues, particularly in the nervous system. Researchers have identified at least three types of pyruvate carboxylase deficiency, which are distinguished by the severity of their signs and symptoms. Type A, which has been identified mostly in people from North America, has moderately severe symptoms that begin in infancy. Characteristic features include developmental delay and a buildup of lactic acid in the blood (lactic acidosis). Increased acidity in the blood can lead to vomiting, abdominal pain, extreme tiredness (fatigue), muscle weakness, and difficulty breathing. In some cases, episodes of lactic acidosis are triggered by an illness or periods without food (fasting). Children with pyruvate carboxylase deficiency type A typically survive only into early childhood. Pyruvate carboxylase deficiency type B has life-threatening signs and symptoms that become apparent shortly after birth. This form of the condition has been reported mostly in Europe, particularly France. Affected infants have severe lactic acidosis, a buildup of ammonia in the blood (hyperammonemia), and liver failure. They experience neurological problems including weak muscle tone (hypotonia), abnormal movements, seizures, and coma. Infants with this form of the condition usually survive for less than 3 months after birth. A milder form of pyruvate carboxylase deficiency, sometimes called type C, has also been described. This type is characterized by slightly increased levels of lactic acid in the blood and minimal signs and symptoms affecting the nervous system. |
frequency | How many people are affected by pyruvate carboxylase deficiency ? | Pyruvate carboxylase deficiency is a rare condition, with an estimated incidence of 1 in 250,000 births worldwide. This disorder appears to be much more common in some Algonkian Indian tribes in eastern Canada. |
genetic changes | What are the genetic changes related to pyruvate carboxylase deficiency ? | Mutations in the PC gene cause pyruvate carboxylase deficiency. The PC gene provides instructions for making an enzyme called pyruvate carboxylase. This enzyme is active in mitochondria, which are the energy-producing centers within cells. It is involved in several important cellular functions including the generation of glucose, a simple sugar that is the body's main energy source. Pyruvate carboxylase also plays a role in the formation of the protective sheath that surrounds certain nerve cells (myelin) and the production of brain chemicals called neurotransmitters. Mutations in the PC gene reduce the amount of pyruvate carboxylase in cells or disrupt the enzyme's activity. The missing or altered enzyme cannot carry out its essential role in generating glucose, which impairs the body's ability to make energy in mitochondria. Additionally, a loss of pyruvate carboxylase allows potentially toxic compounds such as lactic acid and ammonia to build up and damage organs and tissues. Researchers suggest that the loss of pyruvate carboxylase function in the nervous system, particularly the role of the enzyme in myelin formation and neurotransmitter production, also contributes to the neurologic features of pyruvate carboxylase deficiency. |
inheritance | Is pyruvate carboxylase deficiency inherited ? | This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. |
treatment | What are the treatments for pyruvate carboxylase deficiency ? | These resources address the diagnosis or management of pyruvate carboxylase deficiency: - Gene Review: Gene Review: Pyruvate Carboxylase Deficiency - Genetic Testing Registry: Pyruvate carboxylase 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) spondyloepiphyseal dysplasia congenita ? | Spondyloepiphyseal dysplasia congenita is an inherited bone growth disorder that results in short stature (dwarfism), skeletal abnormalities, and problems with vision and hearing. This condition affects the bones of the spine (spondylo-) and the ends (epiphyses) of long bones in the arms and legs. Congenita indicates that the condition is present from birth. People with spondyloepiphyseal dysplasia congenita have short stature from birth, with a very short trunk and neck and shortened limbs. Their hands and feet, however, are usually average-sized. Adult height ranges from 3 feet to just over 4 feet. Abnormal curvature of the spine (kyphoscoliosis and lordosis) becomes more severe during childhood. Instability of the spinal bones (vertebrae) in the neck may increase the risk of spinal cord damage. Other skeletal features include flattened vertebrae (platyspondyly); an abnormality of the hip joint that causes the upper leg bones to turn inward (coxa vara); a foot deformity called a clubfoot; and a broad, barrel-shaped chest. Abnormal development of the chest can cause problems with breathing. Arthritis and decreased joint mobility often develop early in life. People with spondyloepiphyseal dysplasia congenita have mild changes in their facial features. The cheekbones close to the nose may appear flattened. Some infants are born with an opening in the roof of the mouth (a cleft palate). Severe nearsightedness (high myopia) is common, as are other eye problems that can impair vision. About one quarter of people with this condition have hearing loss. |
frequency | How many people are affected by spondyloepiphyseal dysplasia congenita ? | This condition is rare; the exact incidence is unknown. More than 175 cases have been reported in the scientific literature. |
genetic changes | What are the genetic changes related to spondyloepiphyseal dysplasia congenita ? | Spondyloepiphyseal dysplasia congenita is one of a spectrum of skeletal disorders caused by mutations in the COL2A1 gene. This gene provides instructions for making a protein that forms type II collagen. This type of collagen is found mostly in cartilage and in the clear gel that fills the eyeball (the vitreous). The COL2A1 gene is essential for the normal development of bones and other tissues that form the body's supportive framework (connective tissues). Mutations in the COL2A1 gene interfere with the assembly of type II collagen molecules, which prevents bones and other connective tissues from developing properly. |
inheritance | Is spondyloepiphyseal dysplasia congenita 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 spondyloepiphyseal dysplasia congenita ? | These resources address the diagnosis or management of spondyloepiphyseal dysplasia congenita: - Genetic Testing Registry: Spondyloepiphyseal dysplasia congenita - MedlinePlus Encyclopedia: Clubfoot - MedlinePlus Encyclopedia: Lordosis - MedlinePlus Encyclopedia: Retinal Detachment - MedlinePlus Encyclopedia: Scoliosis 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) palmoplantar keratoderma with deafness ? | Palmoplantar keratoderma with deafness is a disorder characterized by skin abnormalities and hearing loss. Affected individuals develop unusually thick skin on the palms of the hands and soles of the feet (palmoplantar keratoderma) beginning in childhood. Hearing loss ranges from mild to profound. It begins in early childhood and gets worse over time. Affected individuals have particular trouble hearing high-pitched sounds. The signs and symptoms of this disorder may vary even within the same family, with some individuals developing only skin abnormalities and others developing only hearing loss. |
frequency | How many people are affected by palmoplantar keratoderma with deafness ? | Palmoplantar keratoderma with deafness is a rare disorder; its prevalence is unknown. At least 10 affected families have been identified. |
genetic changes | What are the genetic changes related to palmoplantar keratoderma with deafness ? | Palmoplantar keratoderma with deafness can be caused by mutations in the GJB2 or MT-TS1 genes. The GJB2 gene provides instructions for making a protein called gap junction beta 2, more commonly known as connexin 26. Connexin 26 is a member of the connexin protein family. Connexin proteins form channels called gap junctions that permit the transport of nutrients, charged atoms (ions), and signaling molecules between neighboring cells that are in contact with each other. Gap junctions made with connexin 26 transport potassium ions and certain small molecules. Connexin 26 is found in cells throughout the body, including the inner ear and the skin. In the inner ear, channels made from connexin 26 are found in a snail-shaped structure called the cochlea. These channels may help to maintain the proper level of potassium ions required for the conversion of sound waves to electrical nerve impulses. This conversion is essential for normal hearing. In addition, connexin 26 may be involved in the maturation of certain cells in the cochlea. Connexin 26 also plays a role in the growth, maturation, and stability of the outermost layer of skin (the epidermis). The GJB2 gene mutations that cause palmoplantar keratoderma with deafness change single protein building blocks (amino acids) in connexin 26. The altered protein probably disrupts the function of normal connexin 26 in cells, and may interfere with the function of other connexin proteins. This disruption could affect skin growth and also impair hearing by disturbing the conversion of sound waves to nerve impulses. Palmoplantar keratoderma with deafness can also be caused by a mutation in the MT-TS1 gene. This gene provides instructions for making a particular type of RNA, a molecule that is a chemical cousin of DNA. This type of RNA, called transfer RNA (tRNA), helps assemble amino acids into full-length, functioning proteins. The MT-TS1 gene provides instructions for a specific form of tRNA that is designated as tRNASer(UCN). This molecule attaches to a particular amino acid, serine (Ser), and inserts it into the appropriate locations in many different proteins. The tRNASer(UCN) molecule is present only in cellular structures called mitochondria. These structures convert energy from food into a form that cells can use. Through a process called oxidative phosphorylation, mitochondria use oxygen, simple sugars, and fatty acids to create adenosine triphosphate (ATP), the cell's main energy source. The tRNASer(UCN) molecule is involved in the assembly of proteins that carry out oxidative phosphorylation. The MT-TS1 gene mutation that causes palmoplantar keratoderma with deafness leads to reduced levels of tRNASer(UCN) to assemble proteins within mitochondria. Reduced production of proteins needed for oxidative phosphorylation may impair the ability of mitochondria to make ATP. Researchers have not determined why the effects of the mutation are limited to cells in the inner ear and the skin in this condition. |
inheritance | Is palmoplantar keratoderma with deafness inherited ? | Palmoplantar keratoderma with deafness can have different inheritance patterns. When this disorder is caused by GJB2 gene mutations, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family. When palmoplantar keratoderma with deafness is caused by mutations in the MT-TS1 gene, it is inherited in a mitochondrial pattern, which is also known as maternal inheritance. This pattern of inheritance applies to genes contained in mitochondrial DNA (mtDNA). Because egg cells, but not sperm cells, contribute mitochondria to the developing embryo, children can only inherit disorders resulting from mtDNA mutations from their mother. These disorders can appear in every generation of a family and can affect both males and females, but fathers do not pass traits associated with changes in mtDNA to their children. |
treatment | What are the treatments for palmoplantar keratoderma with deafness ? | These resources address the diagnosis or management of palmoplantar keratoderma with deafness: - Foundation for Ichthyosis and Related Skin Types: Palmoplantar Keratodermas - Genetic Testing Registry: Keratoderma palmoplantar deafness 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) 47,XYY syndrome ? | 47,XYY syndrome is characterized by an extra copy of the Y chromosome in each of a male's cells. Although males with this condition may be taller than average, this chromosomal change typically causes no unusual physical features. Most males with 47,XYY syndrome have normal sexual development and are able to father children. 47,XYY syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills (such as sitting and walking), weak muscle tone (hypotonia), hand tremors or other involuntary movements (motor tics), and behavioral and emotional difficulties are also possible. These characteristics vary widely among affected boys and men. A small percentage of males with 47,XYY syndrome are diagnosed with autistic spectrum disorders, which are developmental conditions that affect communication and social interaction. |
frequency | How many people are affected by 47,XYY syndrome ? | This condition occurs in about 1 in 1,000 newborn boys. Five to 10 boys with 47,XYY syndrome are born in the United States each day. |
genetic changes | What are the genetic changes related to 47,XYY syndrome ? | People normally have 46 chromosomes in each cell. Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics. Females typically have two X chromosomes (46,XX), and males have one X chromosome and one Y chromosome (46,XY). 47,XYY syndrome is caused by the presence of an extra copy of the Y chromosome in each of a male's cells. As a result of the extra Y chromosome, each cell has a total of 47 chromosomes instead of the usual 46. It is unclear why an extra copy of the Y chromosome is associated with tall stature, learning problems, and other features in some boys and men. Some males with 47,XYY syndrome have an extra Y chromosome in only some of their cells. This phenomenon is called 46,XY/47,XYY mosaicism. |
inheritance | Is 47,XYY syndrome inherited ? | Most cases of 47,XYY syndrome are not inherited. The chromosomal change usually occurs as a random event during the formation of sperm cells. An error in cell division called nondisjunction can result in sperm cells with an extra copy of the Y chromosome. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra Y chromosome in each of the body's cells. 46,XY/47,XYY mosaicism is also not inherited. It occurs as a random event during cell division in early embryonic development. As a result, some of an affected person's cells have one X chromosome and one Y chromosome (46,XY), and other cells have one X chromosome and two Y chromosomes (47,XYY). |
treatment | What are the treatments for 47,XYY syndrome ? | These resources address the diagnosis or management of 47,XYY syndrome: - Association for X and Y Chromosome Variations: Tell Me About 47,XYY - Genetic Testing Registry: Double Y 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) Leydig cell hypoplasia ? | Leydig cell hypoplasia is a condition that affects male sexual development. It is characterized by underdevelopment (hypoplasia) of Leydig cells in the testes. Leydig cells secrete male sex hormones (androgens) that are important for normal male sexual development before birth and during puberty. In Leydig cell hypoplasia, affected individuals with a typical male chromosomal pattern (46,XY) may have a range of genital abnormalities. Affected males may have a small penis (micropenis), the opening of the urethra on the underside of the penis (hypospadias), or a scrotum divided into two lobes (bifid scrotum). Because of these abnormalities, the external genitalia may not look clearly male or clearly female (ambiguous genitalia). In more severe cases of Leydig cell hypoplasia, people with a typical male chromosomal pattern (46,XY) have female external genitalia. They have small testes that are undescended, which means they are abnormally located in the pelvis, abdomen, or groin. People with this form of the disorder do not develop secondary sex characteristics, such as increased body hair, at puberty. Some researchers refer to this form of Leydig cell hypoplasia as type 1 and designate less severe cases as type 2. |
frequency | How many people are affected by Leydig cell hypoplasia ? | Leydig cell hypoplasia is a rare disorder; its prevalence is unknown. |
genetic changes | What are the genetic changes related to Leydig cell hypoplasia ? | Mutations in the LHCGR gene cause Leydig cell hypoplasia. The LHCGR gene provides instructions for making a protein called the luteinizing hormone/chorionic gonadotropin receptor. Receptor proteins have specific sites into which certain other proteins, called ligands, fit like keys into locks. Together, ligands and their receptors trigger signals that affect cell development and function. The protein produced from the LHCGR gene acts as a receptor for two ligands: luteinizing hormone and a similar hormone called chorionic gonadotropin. The receptor allows the body to respond appropriately to these hormones. In males, chorionic gonadotropin stimulates the development of cells in the testes called Leydig cells, and luteinizing hormone triggers these cells to produce androgens. Androgens, including testosterone, are the hormones that control male sexual development and reproduction. In females, luteinizing hormone triggers the release of egg cells from the ovary (ovulation). Chorionic gonadotropin is produced during pregnancy and helps maintain conditions necessary for the pregnancy to continue. The LHCGR gene mutations that cause Leydig cell hypoplasia disrupt luteinizing hormone/chorionic gonadotropin receptor function, impeding the body's ability to react to these hormones. In males, the mutations result in poorly developed or absent Leydig cells and impaired production of testosterone. A lack of testosterone interferes with the development of male reproductive organs before birth and the changes that appear at puberty. Mutations that prevent the production of any functional receptor protein cause the more severe features of Leydig cell hypoplasia, and mutations that allow some receptor protein function cause milder signs and symptoms. |
inheritance | Is Leydig cell hypoplasia 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. Only people who have mutations in both copies of the LHCGR gene and are genetically male (with one X and one Y chromosome in each cell) have the characteristic signs of Leydig cell hypoplasia. Although people who are genetically female (with two X chromosomes in each cell) may inherit mutations in both copies of the LHCGR gene, they do not have Leydig cell hypoplasia because they do not have Leydig cells. They have normal female genitalia and normal breast and pubic hair development, but they may begin menstruation later than usual (after age 16) and have irregular menstrual periods. LHCGR gene mutations in females also prevent ovulation, leading to inability to have children (infertility). |
treatment | What are the treatments for Leydig cell hypoplasia ? | These resources address the diagnosis or management of Leydig cell hypoplasia: - Genetic Testing Registry: Leydig cell agenesis - MedlinePlus Encyclopedia: Ambiguous Genitalia - MedlinePlus Encyclopedia: Hypospadias - MedlinePlus Encyclopedia: Intersex 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) permanent neonatal diabetes mellitus ? | Permanent neonatal diabetes mellitus is a type of diabetes that first appears within the first 6 months of life and persists throughout the lifespan. This form of diabetes is characterized by high blood sugar levels (hyperglycemia) resulting from a shortage of the hormone insulin. Insulin controls how much glucose (a type of sugar) is passed from the blood into cells for conversion to energy. Individuals with permanent neonatal diabetes mellitus experience slow growth before birth (intrauterine growth retardation). Affected infants have hyperglycemia and an excessive loss of fluids (dehydration) and are unable to gain weight and grow at the expected rate (failure to thrive). In some cases, people with permanent neonatal diabetes mellitus also have certain neurological problems, including developmental delay and recurrent seizures (epilepsy). This combination of developmental delay, epilepsy, and neonatal diabetes is called DEND syndrome. Intermediate DEND syndrome is a similar combination but with milder developmental delay and without epilepsy. A small number of individuals with permanent neonatal diabetes mellitus have an underdeveloped pancreas. Because the pancreas produces digestive enzymes as well as secreting insulin and other hormones, affected individuals experience digestive problems such as fatty stools and an inability to absorb fat-soluble vitamins. |
frequency | How many people are affected by permanent neonatal diabetes mellitus ? | About 1 in 400,000 infants are diagnosed with diabetes mellitus in the first few months of life. However, in about half of these babies the condition is transient and goes away on its own by age 18 months. The remainder are considered to have permanent neonatal diabetes mellitus. |
genetic changes | What are the genetic changes related to permanent neonatal diabetes mellitus ? | Permanent neonatal diabetes mellitus may be caused by mutations in several genes. About 30 percent of individuals with permanent neonatal diabetes mellitus have mutations in the KCNJ11 gene. An additional 20 percent of people with permanent neonatal diabetes mellitus have mutations in the ABCC8 gene. These genes provide instructions for making parts (subunits) of the ATP-sensitive potassium (K-ATP) channel. Each K-ATP channel consists of eight subunits, four produced from the KCNJ11 gene and four from the ABCC8 gene. K-ATP channels are found across cell membranes in the insulin-secreting beta cells of the pancreas. These channels open and close in response to the amount of glucose in the bloodstream. Closure of the channels in response to increased glucose triggers the release of insulin out of beta cells and into the bloodstream, which helps control blood sugar levels. Mutations in the KCNJ11 or ABCC8 gene that cause permanent neonatal diabetes mellitus result in K-ATP channels that do not close, leading to reduced insulin secretion from beta cells and impaired blood sugar control. Mutations in the INS gene, which provides instructions for making insulin, have been identified in about 20 percent of individuals with permanent neonatal diabetes mellitus. Insulin is produced in a precursor form called proinsulin, which consists of a single chain of protein building blocks (amino acids). The proinsulin chain is cut (cleaved) to form individual pieces called the A and B chains, which are joined together by connections called disulfide bonds to form insulin. Mutations in the INS gene are believed to disrupt the cleavage of the proinsulin chain or the binding of the A and B chains to form insulin, leading to impaired blood sugar control. Permanent neonatal diabetes mellitus can also be caused by mutations in other genes, some of which have not been identified. |
inheritance | Is permanent neonatal diabetes mellitus inherited ? | Permanent neonatal diabetes mellitus can have different inheritance patterns. When this condition is caused by mutations in the KCNJ11 or INS gene it 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 about 90 percent of these cases, the condition results from new mutations in the gene and occurs in people with no history of the disorder in their family. In the remaining cases, an affected person inherits the mutation from one affected parent. When permanent neonatal diabetes mellitus is caused by mutations in the ABCC8 gene, it may be inherited in either an autosomal dominant or autosomal recessive pattern. In autosomal recessive inheritance, 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 commonly the condition is caused by mutations in other genes, and in these cases it is also inherited in an autosomal recessive pattern. |
treatment | What are the treatments for permanent neonatal diabetes mellitus ? | These resources address the diagnosis or management of permanent neonatal diabetes mellitus: - Gene Review: Gene Review: Permanent Neonatal Diabetes Mellitus - Genetic Testing Registry: Pancreatic agenesis, congenital - Genetic Testing Registry: Permanent neonatal diabetes mellitus - University of Chicago Kovler Diabetes 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) Camurati-Engelmann disease ? | Camurati-Engelmann disease is a condition that mainly affects the bones. People with this disease have increased bone density, particularly affecting the long bones of the arms and legs. In some cases, the skull and hip bones are also affected. The thickened bones can lead to pain in the arms and legs, a waddling walk, muscle weakness, and extreme tiredness. An increase in the density of the skull results in increased pressure on the brain and can cause a variety of neurological problems, including headaches, hearing loss, vision problems, dizziness (vertigo), ringing in the ears (tinnitus), and facial paralysis. The added pressure that thickened bones put on the muscular and skeletal systems can cause abnormal curvature of the spine (scoliosis), joint deformities (contractures), knock knees, and flat feet (pes planus). Other features of Camurati-Engelmann disease include abnormally long limbs in proportion to height, a decrease in muscle mass and body fat, and delayed puberty. The age at which affected individuals first experience symptoms varies greatly; however, most people with this condition develop pain or weakness by adolescence. In some instances, people have the gene mutation that causes Camurati-Engelmann disease but never develop the characteristic features of this condition. |
frequency | How many people are affected by Camurati-Engelmann disease ? | The prevalence of Camurati-Engelmann disease is unknown. Approximately 200 cases have been reported worldwide. |
genetic changes | What are the genetic changes related to Camurati-Engelmann disease ? | Mutations in the TGFB1 gene cause Camurati-Engelmann disease. The TGFB1 gene provides instructions for producing a protein called transforming growth factor beta-1 (TGF-1). The TGF-1 protein helps control the growth and division (proliferation) of cells, the process by which cells mature to carry out specific functions (differentiation), cell movement (motility), and the self-destruction of cells (apoptosis). The TGF-1 protein is found throughout the body and plays a role in development before birth, the formation of blood vessels, the regulation of muscle tissue and body fat development, wound healing, and immune system function. TGF-1 is particularly abundant in tissues that make up the skeleton, where it helps regulate bone growth, and in the intricate lattice that forms in the spaces between cells (the extracellular matrix). Within cells, the TGF-1 protein is turned off (inactive) until it receives a chemical signal to become active. The TGFB1 gene mutations that cause Camurati-Engelmann disease result in the production of a TGF-1 protein that is always turned on (active). Overactive TGF-1 proteins lead to increased bone density and decreased body fat and muscle tissue, contributing to the signs and symptoms of Camurati-Engelmann disease. Some individuals with Camurati-Engelmann disease do not have identified mutations in the TGFB1 gene. In these cases, the cause of the condition is unknown. |
inheritance | Is Camurati-Engelmann disease 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 Camurati-Engelmann disease ? | These resources address the diagnosis or management of Camurati-Engelmann disease: - Gene Review: Gene Review: Camurati-Engelmann Disease - Genetic Testing Registry: Diaphyseal dysplasia 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) congenital contractural arachnodactyly ? | Congenital contractural arachnodactyly is a disorder that affects many parts of the body. People with this condition typically are tall with long limbs (dolichostenomelia) and long, slender fingers and toes (arachnodactyly). They often have permanently bent joints (contractures) that can restrict movement in their hips, knees, ankles, or elbows. Additional features of congenital contractural arachnodactyly include underdeveloped muscles, a rounded upper back that also curves to the side (kyphoscoliosis), permanently bent fingers and toes (camptodactyly), ears that look "crumpled," and a protruding chest (pectus carinatum). Rarely, people with congenital contractural arachnodactyly have heart defects such as an enlargement of the blood vessel that distributes blood from the heart to the rest of the body (aortic root dilatation) or a leak in one of the valves that control blood flow through the heart (mitral valve prolapse). The life expectancy of individuals with congenital contractural arachnodactyly varies depending on the severity of symptoms but is typically not shortened. A rare, severe form of congenital contractural arachnodactyly involves both heart and digestive system abnormalities in addition to the skeletal features described above; individuals with this severe form of the condition usually do not live past infancy. |
frequency | How many people are affected by congenital contractural arachnodactyly ? | The prevalence of congenital contractural arachnodactyly is estimated to be less than 1 in 10,000 worldwide. |
genetic changes | What are the genetic changes related to congenital contractural arachnodactyly ? | Mutations in the FBN2 gene cause congenital contractural arachnodactyly. The FBN2 gene provides instructions for producing the fibrillin-2 protein. Fibrillin-2 binds to other proteins and molecules to form threadlike filaments called microfibrils. Microfibrils become part of the fibers that provide strength and flexibility to connective tissue that supports the body's joints and organs. Additionally, microfibrils regulate the activity of molecules called growth factors. Growth factors enable the growth and repair of tissues throughout the body. Mutations in the FBN2 gene can decrease fibrillin-2 production or result in the production of a protein with impaired function. As a result, microfibril formation is reduced, which probably weakens the structure of connective tissue and disrupts regulation of growth factor activity. The resulting abnormalities of connective tissue underlie the signs and symptoms of congenital contractural arachnodactyly. |
inheritance | Is congenital contractural arachnodactyly 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 congenital contractural arachnodactyly ? | These resources address the diagnosis or management of congenital contractural arachnodactyly: - Gene Review: Gene Review: Congenital Contractural Arachnodactyly - Genetic Testing Registry: Congenital contractural arachnodactyly - MedlinePlus Encyclopedia: Arachnodactyly - MedlinePlus Encyclopedia: Contracture Deformity - MedlinePlus Encyclopedia: Skeletal Limb Abnormalities 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) Cole disease ? | Cole disease is a disorder that affects the skin. People with this disorder have areas of unusually light-colored skin (hypopigmentation), typically on the arms and legs, and spots of thickened skin on the palms of the hands and the soles of the feet (punctate palmoplantar keratoderma). These skin features are present at birth or develop in the first year of life. In some cases, individuals with Cole disease develop abnormal accumulations of the mineral calcium (calcifications) in the tendons, which can cause pain during movement. Calcifications may also occur in the skin or breast tissue. |
frequency | How many people are affected by Cole disease ? | Cole disease is a rare disease; its prevalence is unknown. Only a few affected families have been described in the medical literature. |
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