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What are the genetic changes related to Cohen syndrome ?
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Mutations in the VPS13B gene (frequently called the COH1 gene) cause Cohen syndrome. The function of the protein produced from the VPS13B gene is unknown; however, researchers suggest it may be involved in sorting and transporting proteins inside the cell. Most mutations in the VPS13B gene are believed to prevent cells from producing a functional VPS13B protein. It is unclear how loss of functional VPS13B protein leads to the signs and symptoms of Cohen syndrome.
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Is Cohen syndrome inherited ?
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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.
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What are the treatments for Cohen syndrome ?
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These resources address the diagnosis or management of Cohen syndrome: - Gene Review: Gene Review: Cohen Syndrome - Genetic Testing Registry: Cohen syndrome - MedlinePlus Encyclopedia: Hypotonia 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
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What is (are) leukoencephalopathy with vanishing white matter ?
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Leukoencephalopathy with vanishing white matter is a progressive disorder that mainly affects the brain and spinal cord (central nervous system). This disorder causes deterioration of the central nervous system's white matter, which consists of nerve fibers covered by myelin. Myelin is the fatty substance that insulates and protects nerves. In most cases, people with leukoencephalopathy with vanishing white matter show no signs or symptoms of the disorder at birth. Affected children may have slightly delayed development of motor skills such as crawling or walking. During early childhood, most affected individuals begin to develop motor symptoms, including abnormal muscle stiffness (spasticity) and difficulty with coordinating movements (ataxia). There may also be some deterioration of mental functioning, but this is not usually as pronounced as the motor symptoms. Some affected females may have abnormal development of the ovaries (ovarian dysgenesis). Specific changes in the brain as seen using magnetic resonance imaging (MRI) are characteristic of leukoencephalopathy with vanishing white matter, and may be visible before the onset of symptoms. While childhood onset is the most common form of leukoencephalopathy with vanishing white matter, some severe forms are apparent at birth. A severe, early-onset form seen among the Cree and Chippewayan populations of Quebec and Manitoba is called Cree leukoencephalopathy. Milder forms may not become evident until adolescence or adulthood, when behavioral or psychiatric problems may be the first signs of the disease. Some females with milder forms of leukoencephalopathy with vanishing white matter who survive to adolescence exhibit ovarian dysfunction. This variant of the disorder is called ovarioleukodystrophy. Progression of leukoencephalopathy with vanishing white matter is generally uneven, with periods of relative stability interrupted by episodes of rapid decline. People with this disorder are particularly vulnerable to stresses such as infection, mild head trauma or other injury, or even extreme fright. These stresses may trigger the first symptoms of the condition or worsen existing symptoms, and can cause affected individuals to become lethargic or comatose.
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How many people are affected by leukoencephalopathy with vanishing white matter ?
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The prevalence of leukoencephalopathy with vanishing white matter is unknown. Although it is a rare disorder, it is believed to be one of the most common inherited diseases that affect the white matter.
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What are the genetic changes related to leukoencephalopathy with vanishing white matter ?
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Mutations in the EIF2B1, EIF2B2, EIF2B3, EIF2B4, and EIF2B5 genes cause leukoencephalopathy with vanishing white matter. The EIF2B1, EIF2B2, EIF2B3, EIF2B4 and EIF2B5 genes provide instructions for making the five parts (subunits) of a protein called eIF2B. The eIF2B protein helps regulate overall protein production (synthesis) in the cell by interacting with another protein, eIF2. The eIF2 protein is called an initiation factor because it is involved in starting (initiating) protein synthesis. Proper regulation of protein synthesis is vital for ensuring that the correct levels of protein are available for the cell to cope with changing conditions. For example, cells must synthesize protein much faster if they are multiplying than if they are in a resting state. Mutations have been identified in all five of the genes from which the eIF2B protein is produced, although most of these mutations (about 65 percent) occur in the EIF2B5 gene. These mutations cause partial loss of eIF2B function in various ways. For example, they may impair the ability of one of the protein subunits to form a complex with the others, or make it more difficult for the protein to attach to the initiation factor. Partial loss of eIF2B function makes it more difficult for the body's cells to regulate protein synthesis and deal with changing conditions and stress. Researchers believe that cells in the white matter may be particularly affected by an abnormal response to stress, resulting in the signs and symptoms of leukoencephalopathy with vanishing white matter.
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Is leukoencephalopathy with vanishing white matter inherited ?
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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.
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What are the treatments for leukoencephalopathy with vanishing white matter ?
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These resources address the diagnosis or management of leukoencephalopathy with vanishing white matter: - Gene Review: Gene Review: Childhood Ataxia with Central Nervous System Hypomelination/Vanishing White Matter - Genetic Testing Registry: Leukoencephalopathy with vanishing white matter 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
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What is (are) progressive external ophthalmoplegia ?
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Progressive external ophthalmoplegia is a condition characterized by weakness of the eye muscles. The condition typically appears in adults between ages 18 and 40. The most common signs and symptoms of progressive external ophthalmoplegia are drooping eyelids (ptosis), which can affect one or both eyelids, and weakness or paralysis of the muscles that move the eye (ophthalmoplegia). Affected individuals may also have general weakness of the skeletal muscles (myopathy), particularly in the neck, arms, or legs. The weakness may be especially noticeable during exercise (exercise intolerance). Muscle weakness may also cause difficulty swallowing (dysphagia). When the muscle cells of affected individuals are stained and viewed under a microscope, these cells usually appear abnormal. These abnormal muscle cells contain an excess of structures called mitochondria and are known as ragged-red fibers. Additionally, a close study of muscle cells may reveal abnormalities in a type of DNA found in mitochondria called mitochondrial DNA (mtDNA). Affected individuals often have large deletions of genetic material from mtDNA in muscle tissue. Although muscle weakness is the primary symptom of progressive external ophthalmoplegia, this condition can be accompanied by other signs and symptoms. In these instances, the condition is referred to as progressive external ophthalmoplegia plus (PEO+). Additional signs and symptoms can include hearing loss caused by nerve damage in the inner ear (sensorineural hearing loss), weakness and loss of sensation in the limbs due to nerve damage (neuropathy), impaired muscle coordination (ataxia), a pattern of movement abnormalities known as parkinsonism, or depression. Progressive external ophthalmoplegia is part of a spectrum of disorders with overlapping signs and symptoms. Similar disorders include other conditions caused by POLG gene mutations, such as ataxia neuropathy spectrum, as well as other mtDNA deletion disorders, such as Kearns-Sayre syndrome. Like progressive external ophthalmoplegia, the other conditions in this spectrum can involve weakness of the eye muscles. However, these conditions have many additional features not shared by most people with progressive external ophthalmoplegia.
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How many people are affected by progressive external ophthalmoplegia ?
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The prevalence of progressive external ophthalmoplegia is unknown.
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What are the genetic changes related to progressive external ophthalmoplegia ?
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Progressive external ophthalmoplegia is a condition caused by defects in mitochondria, which are structures within cells that use oxygen to convert the energy from food into a form cells can use. This process is called oxidative phosphorylation. Although most DNA is packaged in chromosomes within the nucleus (nuclear DNA), mitochondria also have a small amount of their own DNA, called mitochondrial DNA or mtDNA. Progressive external ophthalmoplegia can result from mutations in several different genes. In some cases, mutations in the MT-TL1 gene, which is located in mtDNA, cause progressive external ophthalmoplegia. In other cases, mutations in nuclear DNA are responsible for the condition, particularly mutations in the POLG, SLC25A4, and C10orf2 genes. These genes are critical for mtDNA maintenance. Although the mechanism is unclear, mutations in any of these three genes lead to large deletions of mtDNA, ranging from 2,000 to 10,000 DNA building blocks (nucleotides). Researchers have not determined how deletions of mtDNA lead to the specific signs and symptoms of progressive external ophthalmoplegia, although the features of the condition are probably related to impaired oxidative phosphorylation. It has been suggested that eye muscles are commonly affected by mitochondrial defects because they are especially dependent on oxidative phosphorylation for energy.
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Is progressive external ophthalmoplegia inherited ?
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Progressive external ophthalmoplegia can have different inheritance patterns depending on the gene involved. When this condition is caused by mutations in the MT-TL1 gene, it is inherited in a mitochondrial pattern, which is also known as maternal inheritance. This pattern of inheritance applies to genes contained in 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. When the nuclear genes POLG, SLC25A4, or C10orf2 are involved, progressive external ophthalmoplegia is usually inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Certain mutations in the POLG gene can also cause a form of the condition that 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. Some mutations in the POLG gene that cause progressive external ophthalmoplegia occur during a person's lifetime and are not inherited. These genetic changes are called somatic mutations.
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What are the treatments for progressive external ophthalmoplegia ?
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These resources address the diagnosis or management of progressive external ophthalmoplegia: - Gene Review: Gene Review: Mitochondrial DNA Deletion Syndromes - Gene Review: Gene Review: POLG-Related Disorders - Genetic Testing Registry: Autosomal dominant progressive external ophthalmoplegia with mitochondrial DNA deletions 1 - Genetic Testing Registry: Autosomal dominant progressive external ophthalmoplegia with mitochondrial DNA deletions 2 - Genetic Testing Registry: Autosomal dominant progressive external ophthalmoplegia with mitochondrial DNA deletions 3 - Genetic Testing Registry: Progressive external ophthalmoplegia - United Mitochondrial Disease Foundation: Diagnosis of Mitochondrial Disease These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
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What is (are) Duane-radial ray syndrome ?
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Duane-radial ray syndrome is a disorder that affects the eyes and causes abnormalities of bones in the arms and hands. This condition is characterized by a particular problem with eye movement called Duane anomaly (also known as Duane syndrome). This abnormality results from the improper development of certain nerves that control eye movement. Duane anomaly limits outward eye movement (toward the ear), and in some cases may limit inward eye movement (toward the nose). Also, as the eye moves inward, the eye opening becomes narrower and the eyeball may pull back (retract) into its socket. Bone abnormalities in the hands include malformed or absent thumbs, an extra thumb, or a long thumb that looks like a finger. Partial or complete absence of bones in the forearm is also common. Together, these hand and arm abnormalities are known as radial ray malformations. People with the combination of Duane anomaly and radial ray malformations may have a variety of other signs and symptoms. These features include unusually shaped ears, hearing loss, heart and kidney defects, a distinctive facial appearance, an inward- and upward-turning foot (clubfoot), and fused spinal bones (vertebrae). The varied signs and symptoms of Duane-radial ray syndrome often overlap with features of other disorders. For example, acro-renal-ocular syndrome is characterized by Duane anomaly and other eye abnormalities, radial ray malformations, and kidney defects. Both conditions are caused by mutations in the same gene. Based on these similarities, researchers suspect that Duane-radial ray syndrome and acro-renal-ocular syndrome are part of an overlapping set of syndromes with many possible signs and symptoms. The features of Duane-radial ray syndrome are also similar to those of a condition called Holt-Oram syndrome; however, these two disorders are caused by mutations in different genes.
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How many people are affected by Duane-radial ray syndrome ?
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Duane-radial ray syndrome is a rare condition whose prevalence is unknown. Only a few affected families have been reported worldwide.
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What are the genetic changes related to Duane-radial ray syndrome ?
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Duane-radial ray syndrome results from mutations in the SALL4 gene. This gene is part of a group of genes called the SALL family. SALL genes provide instructions for making proteins that are involved in the formation of tissues and organs before birth. The proteins produced from these genes act as transcription factors, which means they attach (bind) to specific regions of DNA and help control the activity of particular genes. The exact function of the SALL4 protein is unclear, although it appears to be important for the normal development of the eyes, heart, and limbs. Mutations in the SALL4 gene prevent cells from making any functional protein from one copy of the gene. It is unclear how a reduction in the amount of the SALL4 protein leads to Duane anomaly, radial ray malformations, and the other features of Duane-radial ray syndrome and similar conditions.
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Is Duane-radial ray syndrome inherited ?
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This condition is inherited in an autosomal dominant pattern, which means one copy of the altered SALL4 gene in each cell is sufficient to cause the disorder. In many cases, an affected person inherits a 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.
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What are the treatments for Duane-radial ray syndrome ?
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These resources address the diagnosis or management of Duane-radial ray syndrome: - Gene Review: Gene Review: SALL4-Related Disorders - Genetic Testing Registry: Duane-radial ray syndrome - 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
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What is (are) X-linked congenital stationary night blindness ?
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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.
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How many people are affected by X-linked congenital stationary night blindness ?
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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.
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What are the genetic changes related to X-linked congenital stationary night blindness ?
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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.
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Is X-linked congenital stationary night blindness inherited ?
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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.
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What are the treatments for X-linked congenital stationary night blindness ?
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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
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What is (are) geleophysic dysplasia ?
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Geleophysic dysplasia is an inherited condition that affects many parts of the body. It is characterized by abnormalities involving the bones, joints, heart, and skin. People with geleophysic dysplasia have short stature with very short hands and feet. Most also develop thickened skin and joint deformities called contractures, both of which significantly limit mobility. Affected individuals usually have a limited range of motion in their fingers, toes, wrists, and elbows. Additionally, contractures in the legs and hips cause many affected people to walk on their toes. The name of this condition, which comes from the Greek words for happy ("gelios") and nature ("physis"), is derived from the good-natured facial appearance seen in most affected individuals. The distinctive facial features associated with this condition include a round face with full cheeks, a small nose with upturned nostrils, a broad nasal bridge, a thin upper lip, upturned corners of the mouth, and a flat area between the upper lip and the nose (philtrum). Geleophysic dysplasia is also characterized by heart (cardiac) problems, particularly abnormalities of the cardiac valves. These valves normally control the flow of blood through the heart. In people with geleophysic dysplasia, the cardiac valves thicken, which impedes blood flow and increases blood pressure in the heart. Other heart problems have also been reported in people with geleophysic dysplasia; these include a narrowing of the artery from the heart to the lungs (pulmonary stenosis) and a hole between the two upper chambers of the heart (atrial septal defect). Other features of geleophysic dysplasia can include an enlarged liver (hepatomegaly) and recurrent respiratory and ear infections. In severe cases, a narrowing of the windpipe (tracheal stenosis) can cause serious breathing problems. As a result of heart and respiratory abnormalities, geleophysic dysplasia is often life-threatening in childhood. However, some affected people have lived into adulthood.
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How many people are affected by geleophysic dysplasia ?
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Geleophysic dysplasia is a rare disorder whose prevalence is unknown. More than 30 affected individuals have been reported.
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What are the genetic changes related to geleophysic dysplasia ?
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Geleophysic dysplasia results from mutations in the ADAMTSL2 gene. This gene provides instructions for making a protein whose function is unclear. The protein is found in the extracellular matrix, which is the intricate lattice of proteins and other molecules that forms in the spaces between cells. Studies suggest that the ADAMTSL2 protein may play a role in the microfibrillar network, which is an organized clustering of thread-like filaments (called microfibrils) in the extracellular matrix. This network provides strength and flexibility to tissues throughout the body. Mutations in the ADAMTSL2 protein likely change the protein's 3-dimensional structure. Through a process that is poorly understood, ADAMTSL2 gene mutations alter the microfibrillar network in many different tissues. Impairment of this essential network disrupts the normal functions of cells, which likely contributes to the varied signs and symptoms of geleophysic dysplasia. Researchers are working to determine how mutations in the ADAMTSL2 gene lead to short stature, heart disease, and the other features of this condition.
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Is geleophysic dysplasia inherited ?
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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.
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What are the treatments for geleophysic dysplasia ?
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These resources address the diagnosis or management of geleophysic dysplasia: - Gene Review: Gene Review: Geleophysic Dysplasia - Genetic Testing Registry: Geleophysic dysplasia 2 - MedlinePlus Encyclopedia: Short Stature 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
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What is (are) Alagille syndrome ?
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Alagille syndrome is a genetic disorder that can affect the liver, heart, and other parts of the body. One of the major features of Alagille syndrome is liver damage caused by abnormalities in the bile ducts. These ducts carry bile (which helps to digest fats) from the liver to the gallbladder and small intestine. In Alagille syndrome, the bile ducts may be narrow, malformed, and reduced in number (bile duct paucity). As a result, bile builds up in the liver and causes scarring that prevents the liver from working properly to eliminate wastes from the bloodstream. Signs and symptoms arising from liver damage in Alagille syndrome may include a yellowish tinge in the skin and the whites of the eyes (jaundice), itchy skin, and deposits of cholesterol in the skin (xanthomas). Alagille syndrome is also associated with several heart problems, including impaired blood flow from the heart into the lungs (pulmonic stenosis). Pulmonic stenosis may occur along with a hole between the two lower chambers of the heart (ventricular septal defect) and other heart abnormalities. This combination of heart defects is called tetralogy of Fallot. People with Alagille syndrome may have distinctive facial features including a broad, prominent forehead; deep-set eyes; and a small, pointed chin. The disorder may also affect the blood vessels within the brain and spinal cord (central nervous system) and the kidneys. Affected individuals may have an unusual butterfly shape of the bones of the spinal column (vertebrae) that can be seen in an x-ray. Problems associated with Alagille syndrome generally become evident in infancy or early childhood. The severity of the disorder varies among affected individuals, even within the same family. Symptoms range from so mild as to go unnoticed to severe heart and/or liver disease requiring transplantation. Some people with Alagille syndrome may have isolated signs of the disorder, such as a heart defect like tetralogy of Fallot, or a characteristic facial appearance. These individuals do not have liver disease or other features typical of the disorder.
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How many people are affected by Alagille syndrome ?
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The estimated prevalence of Alagille syndrome is 1 in 70,000 newborns. This figure is based on diagnoses of liver disease in infants, and may be an underestimation because some people with Alagille syndrome do not develop liver disease during infancy.
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What are the genetic changes related to Alagille syndrome ?
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In more than 90 percent of cases, mutations in the JAG1 gene cause Alagille syndrome. Another 7 percent of individuals with Alagille syndrome have small deletions of genetic material on chromosome 20 that include the JAG1 gene. A few people with Alagille syndrome have mutations in a different gene, called NOTCH2. The JAG1 and NOTCH2 genes provide instructions for making proteins that fit together to trigger interactions called Notch signaling between neighboring cells during embryonic development. This signaling influences how the cells are used to build body structures in the developing embryo. Changes in either the JAG1 gene or NOTCH2 gene probably disrupt the Notch signaling pathway. As a result, errors may occur during development, especially affecting the bile ducts, heart, spinal column, and certain facial features.
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Is Alagille syndrome inherited ?
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This condition is inherited in an autosomal dominant pattern, which means one copy of the altered or deleted gene in each cell is sufficient to cause the disorder. In approximately 30 to 50 percent of cases, an affected person inherits the mutation or deletion from one affected parent. Other cases result from new mutations in the gene or new deletions of genetic material on chromosome 20 that occur as random events during the formation of reproductive cells (eggs or sperm) or in early fetal development. These cases occur in people with no history of the disorder in their family.
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What are the treatments for Alagille syndrome ?
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These resources address the diagnosis or management of Alagille syndrome: - Boston Children's Hospital - Children's Hospital of Philadelphia - Children's Hospital of Pittsburgh - Gene Review: Gene Review: Alagille Syndrome - Genetic Testing Registry: Alagille syndrome 1 - Genetic Testing Registry: Arteriohepatic dysplasia - MedlinePlus Encyclopedia: Tetralogy of Fallot 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
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What is (are) TK2-related mitochondrial DNA depletion syndrome, myopathic form ?
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TK2-related mitochondrial DNA depletion syndrome, myopathic form (TK2-MDS) is an inherited condition that causes progressive muscle weakness (myopathy). The signs and symptoms of TK2-MDS typically begin in early childhood. Development is usually normal early in life, but as muscle weakness progresses, people with TK2-MDS lose motor skills such as standing, walking, eating, and talking. Some affected individuals have increasing weakness in the muscles that control eye movement, leading to droopy eyelids (progressive external ophthalmoplegia). Most often in TK2-MDS, the muscles are the only affected tissues; however, the liver may be enlarged (hepatomegaly), seizures can occur, and hearing loss caused by nerve damage in the inner ear (sensorineural hearing loss) may be present. Intelligence is usually not affected. As the disorder worsens, the muscles that control breathing become weakened and affected individuals frequently have to rely on mechanical ventilation. Respiratory failure is the most common cause of death in people with TK2-MDS, often occurring in childhood. Rarely, the disorder progresses slowly and affected individuals survive into adolescence or adulthood.
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How many people are affected by TK2-related mitochondrial DNA depletion syndrome, myopathic form ?
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The prevalence of TK2-MDS is unknown. Approximately 45 cases have been described.
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What are the genetic changes related to TK2-related mitochondrial DNA depletion syndrome, myopathic form ?
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As the condition name suggests, mutations in the TK2 gene cause TK2-MDS. The TK2 gene provides instructions for making an enzyme called thymidine kinase 2 that functions within cell structures called mitochondria, which are found in all tissues. Mitochondria are involved in a wide variety of cellular activities, including energy production; chemical signaling; and regulation of cell growth, cell division, and cell death. Mitochondria contain their own genetic material, known as mitochondrial DNA (mtDNA), which is essential for the normal function of these structures. Thymidine kinase 2 is involved in the production and maintenance of mtDNA. Specifically, this enzyme plays a role in recycling mtDNA building blocks (nucleotides) so that errors in mtDNA sequencing can be repaired and new mtDNA molecules can be produced. Mutations in the TK2 gene reduce the production or activity of thymidine kinase 2. A decrease in enzyme activity impairs recycling of mtDNA nucleotides, causing a shortage of nucleotides available for the repair and production of mtDNA molecules. A reduction in the amount of mtDNA (known as mtDNA depletion) impairs mitochondrial function. Greater mtDNA depletion tends to cause more severe signs and symptoms. The muscle cells of people with TK2-MDS have very low amounts of mtDNA, ranging from 5 to 30 percent of normal. Other tissues can have 60 percent of normal to normal amounts of mtDNA. It is unclear why TK2 gene mutations typically affect only muscle tissue, but the high energy demands of muscle cells may make them the most susceptible to cell death when mtDNA is lost and less energy is produced in cells. The brain and the liver also have high energy demands, which may explain why these organs are affected in severe cases of TK2-MDS.
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Is TK2-related mitochondrial DNA depletion syndrome, myopathic form inherited ?
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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.
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What are the treatments for TK2-related mitochondrial DNA depletion syndrome, myopathic form ?
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These resources address the diagnosis or management of TK2-related mitochondrial DNA depletion syndrome, myopathic form: - Cincinnati Children's Hospital: Mitochondrial Diseases Program - Gene Review: Gene Review: TK2-Related Mitochondrial DNA Depletion Syndrome, Myopathic Form 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
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What is (are) gray platelet syndrome ?
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Gray platelet syndrome is a bleeding disorder associated with abnormal platelets, which are blood cell fragments involved in blood clotting. People with this condition tend to bruise easily and have an increased risk of nosebleeds (epistaxis). They may also experience abnormally heavy or extended bleeding following surgery, dental work, or minor trauma. Women with gray platelet syndrome often have irregular, heavy periods (menometrorrhagia). These bleeding problems are usually mild to moderate, but they have been life-threatening in a few affected individuals. A condition called myelofibrosis, which is a buildup of scar tissue (fibrosis) in the bone marrow, is another common feature of gray platelet syndrome. Bone marrow is the spongy tissue in the center of long bones that produces most of the blood cells the body needs, including platelets. The scarring associated with myelofibrosis damages bone marrow, preventing it from making enough blood cells. Other organs, particularly the spleen, start producing more blood cells to compensate; this process often leads to an enlarged spleen (splenomegaly).
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How many people are affected by gray platelet syndrome ?
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Gray platelet syndrome appears to be a rare disorder. About 60 cases have been reported worldwide.
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What are the genetic changes related to gray platelet syndrome ?
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Gray platelet syndrome can be caused by mutations in the NBEAL2 gene. Little is known about the protein produced from this gene. It appears to play a role in the formation of alpha-granules, which are sacs inside platelets that contain growth factors and other proteins that are important for blood clotting and wound healing. In response to an injury that causes bleeding, the proteins stored in alpha-granules help platelets stick to one another to form a plug that seals off damaged blood vessels and prevents further blood loss. Mutations in the NBEAL2 gene disrupt the normal production of alpha-granules. Without alpha-granules, platelets are unusually large and fewer in number than usual (macrothrombocytopenia). The abnormal platelets also appear gray when viewed under a microscope, which gives this condition its name. A lack of alpha-granules impairs the normal activity of platelets during blood clotting, increasing the risk of abnormal bleeding. Myelofibrosis is thought to occur because the growth factors and other proteins that are normally packaged into alpha-granules leak out into the bone marrow. The proteins lead to fibrosis that affects the bone marrow's ability to make new blood cells. Some people with gray platelet syndrome do not have an identified mutation in the NBEAL2 gene. In these individuals, the cause of the condition is unknown.
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Is gray platelet syndrome inherited ?
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When gray platelet syndrome is caused by NBEAL2 gene mutations, it has an autosomal recessive pattern of inheritance, 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 altered gene in each cell. Gray platelet syndrome can also be inherited in an autosomal dominant pattern, which means one copy of an altered gene in each cell is sufficient to cause the disorder. An affected person often inherits the condition from one affected parent. Researchers are working to determine which gene or genes are associated with the autosomal dominant form of gray platelet syndrome.
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What are the treatments for gray platelet syndrome ?
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These resources address the diagnosis or management of gray platelet syndrome: - Genetic Testing Registry: Gray platelet syndrome - National Heart Lung and Blood Institute: How is Thrombocytopenia Treated? 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
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What is (are) fibrodysplasia ossificans progressiva ?
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Fibrodysplasia ossificans progressiva (FOP) is a disorder in which muscle tissue and connective tissue such as tendons and ligaments are gradually replaced by bone (ossified), forming bone outside the skeleton (extra-skeletal or heterotopic bone) that constrains movement. This process generally becomes noticeable in early childhood, starting with the neck and shoulders and proceeding down the body and into the limbs. Extra-skeletal bone formation causes progressive loss of mobility as the joints become affected. Inability to fully open the mouth may cause difficulty in speaking and eating. Over time, people with this disorder may experience malnutrition due to their eating problems. They may also have breathing difficulties as a result of extra bone formation around the rib cage that restricts expansion of the lungs. Any trauma to the muscles of an individual with fibrodysplasia ossificans progressiva, such as a fall or invasive medical procedures, may trigger episodes of muscle swelling and inflammation (myositis) followed by more rapid ossification in the injured area. Flare-ups may also be caused by viral illnesses such as influenza. People with fibrodysplasia ossificans progressiva are generally born with malformed big toes. This abnormality of the big toes is a characteristic feature that helps to distinguish this disorder from other bone and muscle problems. Affected individuals may also have short thumbs and other skeletal abnormalities.
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How many people are affected by fibrodysplasia ossificans progressiva ?
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Fibrodysplasia ossificans progressiva is a very rare disorder, believed to occur in approximately 1 in 2 million people worldwide. Several hundred cases have been reported.
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What are the genetic changes related to fibrodysplasia ossificans progressiva ?
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Mutations in the ACVR1 gene cause fibrodysplasia ossificans progressiva. The ACVR1 gene provides instructions for producing a member of a protein family called bone morphogenetic protein (BMP) type I receptors. The ACVR1 protein is found in many tissues of the body including skeletal muscle and cartilage. It helps to control the growth and development of the bones and muscles, including the gradual replacement of cartilage by bone (ossification) that occurs in normal skeletal maturation from birth to young adulthood. Researchers believe that a mutation in the ACVR1 gene may change the shape of the receptor under certain conditions and disrupt mechanisms that control the receptor's activity. As a result, the receptor may be constantly turned on (constitutive activation). Constitutive activation of the receptor causes overgrowth of bone and cartilage and fusion of joints, resulting in the signs and symptoms of fibrodysplasia ossificans progressiva.
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Is fibrodysplasia ossificans progressiva inherited ?
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This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Most cases of fibrodysplasia ossificans progressiva result from new mutations in the gene. These cases occur in people with no history of the disorder in their family. In a small number of cases, an affected person has inherited the mutation from one affected parent.
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What are the treatments for fibrodysplasia ossificans progressiva ?
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These resources address the diagnosis or management of fibrodysplasia ossificans progressiva: - Genetic Testing Registry: Progressive myositis ossificans 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
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What is (are) central core disease ?
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Central core disease is a disorder that affects muscles used for movement (skeletal muscles). This condition causes muscle weakness that ranges from almost unnoticeable to very severe. Most people with central core disease experience persistent, mild muscle weakness that does not worsen with time. This weakness affects the muscles near the center of the body (proximal muscles), particularly muscles in the upper legs and hips. Muscle weakness causes affected infants to appear "floppy" and can delay the development of motor skills such as sitting, standing, and walking. In severe cases, affected infants experience profoundly weak muscle tone (hypotonia) and serious or life-threatening breathing problems. Central core disease is also associated with skeletal abnormalities such as abnormal curvature of the spine (scoliosis), hip dislocation, and joint deformities called contractures that restrict the movement of certain joints. Many people with central core disease also have an increased risk of developing a severe reaction to certain drugs used during surgery and other invasive procedures. This reaction is called malignant hyperthermia. Malignant hyperthermia occurs in response to some anesthetic gases, which are used to block the sensation of pain, and with a particular type of muscle relaxant. If given these drugs, people at risk for malignant hyperthermia may experience muscle rigidity, breakdown of muscle fibers (rhabdomyolysis), a high fever, increased acid levels in the blood and other tissues (acidosis), and a rapid heart rate. The complications of malignant hyperthermia can be life-threatening unless they are treated promptly. Central core disease gets its name from disorganized areas called cores, which are found in the center of muscle fibers in many affected individuals. These abnormal regions can only be seen under a microscope. Although the presence of cores can help doctors diagnose central core disease, it is unclear how they are related to muscle weakness and the other features of this condition.
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How many people are affected by central core disease ?
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Central core disease is probably an uncommon condition, although its incidence is unknown.
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What are the genetic changes related to central core disease ?
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Mutations in the RYR1 gene cause central core disease. The RYR1 gene provides instructions for making a protein called ryanodine receptor 1. This protein plays an essential role in skeletal muscles. For the body to move normally, these muscles must tense (contract) and relax in a coordinated way. Muscle contractions are triggered by the flow of charged atoms (ions) into muscle cells. The ryanodine receptor 1 protein forms a channel that releases calcium ions stored within muscle cells. The resulting increase in calcium ion concentration inside muscle cells stimulates muscle fibers to contract, allowing the body to move. Mutations in the RYR1 gene change the structure of ryanodine receptor 1, allowing calcium ions to "leak" through the abnormal channel or impairing the channel's ability to release stored calcium ions at the correct time. This disruption in calcium ion transport prevents muscles from contracting normally, leading to the muscle weakness characteristic of central core disease.
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Is central core disease inherited ?
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Central core disease is most often 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 may result from new mutations in the gene. These cases occur in people with no history of the disorder in their family. Less commonly, central core disease 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 typically do not show signs and symptoms of the condition. People who carry one mutated copy of the RYR1 gene, however, may be at increased risk for malignant hyperthermia.
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What are the treatments for central core disease ?
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These resources address the diagnosis or management of central core disease: - Gene Review: Gene Review: Central Core Disease - Genetic Testing Registry: Central core disease - MedlinePlus Encyclopedia: Hypotonia - MedlinePlus Encyclopedia: Malignant Hyperthermia 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
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What is (are) oculocutaneous albinism ?
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Oculocutaneous albinism is a group of conditions that affect coloring (pigmentation) of the skin, hair, and eyes. Affected individuals typically have very fair skin and white or light-colored hair. Long-term sun exposure greatly increases the risk of skin damage and skin cancers, including an aggressive form of skin cancer called melanoma, in people with this condition. Oculocutaneous albinism also reduces pigmentation of the colored part of the eye (the iris) and the light-sensitive tissue at the back of the eye (the retina). People with this condition usually have vision problems such as reduced sharpness; rapid, involuntary eye movements (nystagmus); and increased sensitivity to light (photophobia). Researchers have identified multiple types of oculocutaneous albinism, which are distinguished by their specific skin, hair, and eye color changes and by their genetic cause. Oculocutaneous albinism type 1 is characterized by white hair, very pale skin, and light-colored irises. Type 2 is typically less severe than type 1; the skin is usually a creamy white color and hair may be light yellow, blond, or light brown. Type 3 includes a form of albinism called rufous oculocutaneous albinism, which usually affects dark-skinned people. Affected individuals have reddish-brown skin, ginger or red hair, and hazel or brown irises. Type 3 is often associated with milder vision abnormalities than the other forms of oculocutaneous albinism. Type 4 has signs and symptoms similar to those seen with type 2. Several additional types of this disorder have been proposed, each affecting one or a few families.
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How many people are affected by oculocutaneous albinism ?
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Overall, an estimated 1 in 20,000 people worldwide are born with oculocutaneous albinism. The condition affects people in many ethnic groups and geographical regions. Types 1 and 2 are the most common forms of this condition; types 3 and 4 are less common. Type 2 occurs more frequently in African Americans, some Native American groups, and people from sub-Saharan Africa. Type 3, specifically rufous oculocutaneous albinism, has been described primarily in people from southern Africa. Studies suggest that type 4 occurs more frequently in the Japanese and Korean populations than in people from other parts of the world.
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What are the genetic changes related to oculocutaneous albinism ?
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Oculocutaneous albinism can result from mutations in several genes, including TYR, OCA2, TYRP1, and SLC45A2. Changes in the TYR gene cause type 1; mutations in the OCA2 gene are responsible for type 2; TYRP1 mutations cause type 3; and changes in the SLC45A2 gene result in type 4. Mutations in additional genes likely underlie the other forms of this disorder. The genes associated with oculocutaneous albinism are involved in producing a pigment called melanin, which is the substance that gives skin, hair, and eyes their color. In the retina, melanin also plays a role in normal vision. Mutations in any of these genes disrupt the ability of cells to make melanin, which reduces pigmentation in the skin, hair, and eyes. A lack of melanin in the retina leads to the vision problems characteristic of oculocutaneous albinism. Alterations in the MC1R gene can change the appearance of people with oculocutaneous albinism type 2. This gene helps regulate melanin production and is responsible for some normal variation in pigmentation. People with genetic changes in both the OCA2 and MC1R genes have many of the usual features of oculocutaneous albinism type 2, including light-colored eyes and vision problems; however, they typically have red hair instead of the usual yellow, blond, or light brown hair seen with this condition. Some individuals with oculocutaneous albinism do not have mutations in any of the known genes. In these people, the genetic cause of the condition is unknown.
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Is oculocutaneous albinism inherited ?
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Oculocutaneous albinism is inherited in an autosomal recessive pattern, which means both copies of a 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 they do not show signs and symptoms of the condition.
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What are the treatments for oculocutaneous albinism ?
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These resources address the diagnosis or management of oculocutaneous albinism: - Gene Review: Gene Review: Oculocutaneous Albinism Type 1 - Gene Review: Gene Review: Oculocutaneous Albinism Type 2 - Gene Review: Gene Review: Oculocutaneous Albinism Type 4 - Genetic Testing Registry: Oculocutaneous albinism - MedlinePlus Encyclopedia: Albinism 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
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What is (are) aromatic l-amino acid decarboxylase deficiency ?
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Aromatic l-amino acid decarboxylase (AADC) deficiency is an inherited disorder that affects the way signals are passed between certain cells in the nervous system. Signs and symptoms of AADC deficiency generally appear in the first year of life. Affected infants may have severe developmental delay, weak muscle tone (hypotonia), muscle stiffness, difficulty moving, and involuntary writhing movements of the limbs (athetosis). They may be lacking in energy (lethargic), feed poorly, startle easily, and have sleep disturbances. People with AADC deficiency may also experience episodes called oculogyric crises that involve abnormal rotation of the eyeballs; extreme irritability and agitation; and pain, muscle spasms, and uncontrolled movements, especially of the head and neck. AADC deficiency may affect the autonomic nervous system, which controls involuntary body processes such as the regulation of blood pressure and body temperature. Resulting signs and symptoms can include droopy eyelids (ptosis), constriction of the pupils of the eyes (miosis), inappropriate or impaired sweating, nasal congestion, drooling, reduced ability to control body temperature, low blood pressure (hypotension), backflow of acidic stomach contents into the esophagus (gastroesophageal reflux), low blood sugar (hypoglycemia), fainting (syncope), and cardiac arrest. Signs and symptoms of AADC deficiency tend to worsen late in the day or when the individual is tired, and improve after sleep.
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How many people are affected by aromatic l-amino acid decarboxylase deficiency ?
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AADC deficiency is a rare disorder. Only about 100 people with this condition have been described in the medical literature worldwide; about 20 percent of these individuals are from Taiwan.
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What are the genetic changes related to aromatic l-amino acid decarboxylase deficiency ?
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Mutations in the DDC gene cause AADC deficiency. The DDC gene provides instructions for making the AADC enzyme, which is important in the nervous system. This enzyme helps produce dopamine and serotonin from other molecules. Dopamine and serotonin are neurotransmitters, which are chemical messengers that transmit signals between nerve cells, both in the brain and spinal cord (central nervous system) and in other parts of the body (peripheral nervous system). Mutations in the DDC gene result in reduced activity of the AADC enzyme. Without enough of this enzyme, nerve cells produce less dopamine and serotonin. Dopamine and serotonin are necessary for normal nervous system function, and changes in the levels of these neurotransmitters contribute to the developmental delay, intellectual disability, abnormal movements, and autonomic dysfunction seen in people with AADC deficiency.
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Is aromatic l-amino acid decarboxylase deficiency inherited ?
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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.
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What are the treatments for aromatic l-amino acid decarboxylase deficiency ?
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These resources address the diagnosis or management of aromatic l-amino acid decarboxylase deficiency: - Genetic Testing Registry: Deficiency of aromatic-L-amino-acid decarboxylase 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
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What is (are) Pelizaeus-Merzbacher disease ?
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Pelizaeus-Merzbacher disease is an inherited condition involving the brain and spinal cord (central nervous system). This disease is one of a group of genetic disorders called leukodystrophies. Leukodystrophies are characterized by degeneration of myelin, which is the covering that protects nerves and promotes the efficient transmission of nerve impulses. Pelizaeus-Merzbacher disease is caused by an inability to form myelin (dysmyelination). As a result, individuals with this condition have impaired intellectual functions, such as language and memory, and delayed motor skills, such as coordination and walking. Typically, motor skills are more severely affected than intellectual function; motor skills development tends to occur more slowly and usually stops in a person's teens, followed by gradual deterioration. Pelizaeus-Merzbacher disease is divided into classic and connatal types. Although these two types differ in severity, their features can overlap. Classic Pelizaeus-Merzbacher disease is the more common type. Within the first year of life, those affected with classic Pelizaeus-Merzbacher disease typically experience weak muscle tone (hypotonia), involuntary movements of the eyes (nystagmus), and delayed development of motor skills such as crawling or walking. As the child gets older, nystagmus usually stops but other movement disorders develop, including muscle stiffness (spasticity), problems with movement and balance (ataxia), and involuntary jerking (choreiform movements). Connatal Pelizaeus-Merzbacher disease is the more severe of the two types. Symptoms can begin in infancy and include problems feeding, a whistling sound when breathing, progressive spasticity leading to joint deformities (contractures) that restrict movement, speech difficulties (dysarthria), ataxia, and seizures. Those affected with connatal Pelizaeus-Merzbacher disease show little development of motor skills and intellectual function.
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How many people are affected by Pelizaeus-Merzbacher disease ?
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The prevalence of Pelizaeus-Merzbacher disease is estimated to be 1 in 200,000 to 500,000 males in the United States. This condition rarely affects females.
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What are the genetic changes related to Pelizaeus-Merzbacher disease ?
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Mutations in the PLP1 gene cause Pelizaeus-Merzbacher disease. The PLP1 gene provides instructions for producing proteolipid protein 1 and a modified version (isoform) of proteolipid protein 1, called DM20. Proteolipid protein 1 and DM20 are primarily located in the central nervous system and are the main proteins found in myelin, the fatty covering that insulates nerve fibers. A lack of proteolipid protein 1 and DM20 can cause dysmyelination, which can impair nervous system function, resulting in the signs and symptoms of Pelizaeus-Merzbacher disease. It is estimated that 5 percent to 20 percent of people with Pelizaeus-Merzbacher disease do not have identified mutations in the PLP1 gene. In these cases, the cause of the condition is unknown.
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Is Pelizaeus-Merzbacher disease inherited ?
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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 males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. Because females have two copies of the X chromosome, one altered copy of the gene in each cell usually leads to less severe symptoms in females than in males, or may cause no symptoms at all. 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. She can pass on the gene, but generally does not experience signs and symptoms of the disorder. Some females who carry a PLP1 mutation, however, may experience muscle stiffness and a decrease in intellectual function. Females with one PLP1 mutation have an increased risk of experiencing progressive deterioration of cognitive functions (dementia) later in life.
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What are the treatments for Pelizaeus-Merzbacher disease ?
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These resources address the diagnosis or management of Pelizaeus-Merzbacher disease: - Gene Review: Gene Review: PLP1-Related Disorders - Genetic Testing Registry: Pelizaeus-Merzbacher disease These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
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What is (are) thanatophoric dysplasia ?
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Thanatophoric dysplasia is a severe skeletal disorder characterized by extremely short limbs and folds of extra (redundant) skin on the arms and legs. Other features of this condition include a narrow chest, short ribs, underdeveloped lungs, and an enlarged head with a large forehead and prominent, wide-spaced eyes. Researchers have described two major forms of thanatophoric dysplasia, type I and type II. Type I thanatophoric dysplasia is distinguished by the presence of curved thigh bones and flattened bones of the spine (platyspondyly). Type II thanatophoric dysplasia is characterized by straight thigh bones and a moderate to severe skull abnormality called a cloverleaf skull. The term thanatophoric is Greek for "death bearing." Infants with thanatophoric dysplasia are usually stillborn or die shortly after birth from respiratory failure; however, a few affected individuals have survived into childhood with extensive medical help.
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How many people are affected by thanatophoric dysplasia ?
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This condition occurs in 1 in 20,000 to 50,000 newborns. Type I thanatophoric dysplasia is more common than type II.
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What are the genetic changes related to thanatophoric dysplasia ?
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Mutations in the FGFR3 gene cause thanatophoric dysplasia. Both types of this condition result from mutations in the FGFR3 gene. This gene provides instructions for making a protein that is involved in the development and maintenance of bone and brain tissue. Mutations in this gene cause the FGFR3 protein to be overly active, which leads to the severe disturbances in bone growth that are characteristic of thanatophoric dysplasia. It is not known how FGFR3 mutations cause the brain and skin abnormalities associated with this disorder.
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Is thanatophoric dysplasia inherited ?
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Thanatophoric dysplasia is considered an autosomal dominant disorder because one mutated copy of the FGFR3 gene in each cell is sufficient to cause the condition. Virtually all cases of thanatophoric dysplasia are caused by new mutations in the FGFR3 gene and occur in people with no history of the disorder in their family. No affected individuals are known to have had children; therefore, the disorder has not been passed to the next generation.
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What are the treatments for thanatophoric dysplasia ?
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These resources address the diagnosis or management of thanatophoric dysplasia: - Gene Review: Gene Review: Thanatophoric Dysplasia - Genetic Testing Registry: Thanatophoric dysplasia type 1 - Genetic Testing Registry: Thanatophoric dysplasia, type 2 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
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What is (are) Pallister-Hall syndrome ?
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Pallister-Hall syndrome is a disorder that affects the development of many parts of the body. Most people with this condition have extra fingers and/or toes (polydactyly), and the skin between some fingers or toes may be fused (cutaneous syndactyly). An abnormal growth in the brain called a hypothalamic hamartoma is characteristic of this disorder. In many cases, these growths do not cause any medical problems; however, some hypothalamic hamartomas lead to seizures or hormone abnormalities that can be life-threatening in infancy. Other features of Pallister-Hall syndrome include a malformation of the airway called a bifid epiglottis, an obstruction of the anal opening (imperforate anus), and kidney abnormalities. Although the signs and symptoms of this disorder vary from mild to severe, only a small percentage of affected people have serious complications.
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How many people are affected by Pallister-Hall syndrome ?
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This condition is very rare; its prevalence is unknown.
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What are the genetic changes related to Pallister-Hall syndrome ?
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Mutations in the GLI3 gene cause Pallister-Hall syndrome. The GLI3 gene provides instructions for making a protein that controls gene expression, which is a process that regulates whether genes are turned on or off in particular cells. By interacting with certain genes at specific times during development, the GLI3 protein plays a role in the normal shaping (patterning) of many organs and tissues before birth. Mutations that cause Pallister-Hall syndrome typically lead to the production of an abnormally short version of the GLI3 protein. Unlike the normal GLI3 protein, which can turn target genes on or off, the short protein can only turn off (repress) target genes. Researchers are working to determine how this change in the protein's function affects early development. It remains uncertain how GLI3 mutations can cause polydactyly, hypothalamic hamartoma, and the other features of Pallister-Hall syndrome.
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Is Pallister-Hall syndrome inherited ?
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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 some cases, an affected person inherits a mutation in the GLI3 gene 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.
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What are the treatments for Pallister-Hall syndrome ?
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These resources address the diagnosis or management of Pallister-Hall syndrome: - Gene Review: Gene Review: Pallister-Hall Syndrome - Genetic Testing Registry: Pallister-Hall syndrome - MedlinePlus Encyclopedia: Epiglottis (Image) - MedlinePlus Encyclopedia: Imperforate Anus - MedlinePlus Encyclopedia: Polydactyly 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
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What is (are) GM1 gangliosidosis ?
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GM1 gangliosidosis is an inherited disorder that progressively destroys nerve cells (neurons) in the brain and spinal cord. Some researchers classify this condition into three major types based on the age at which signs and symptoms first appear. Although the three types differ in severity, their features can overlap significantly. Because of this overlap, other researchers believe that GM1 gangliosidosis represents a continuous disease spectrum instead of three distinct types. The signs and symptoms of the most severe form of GM1 gangliosidosis, called type I or the infantile form, usually become apparent by the age of 6 months. Infants with this form of the disorder typically appear normal until their development slows and muscles used for movement weaken. Affected infants eventually lose the skills they had previously acquired (developmentally regress) and may develop an exaggerated startle reaction to loud noises. As the disease progresses, children with GM1 gangliosidosis type I develop an enlarged liver and spleen (hepatosplenomegaly), skeletal abnormalities, seizures, profound intellectual disability, and clouding of the clear outer covering of the eye (the cornea). Loss of vision occurs as the light-sensing tissue at the back of the eye (the retina) gradually deteriorates. An eye abnormality called a cherry-red spot, which can be identified with an eye examination, is characteristic of this disorder. In some cases, affected individuals have distinctive facial features that are described as "coarse," enlarged gums (gingival hypertrophy), and an enlarged and weakened heart muscle (cardiomyopathy). Individuals with GM1 gangliosidosis type I usually do not survive past early childhood. Type II GM1 gangliosidosis consists of intermediate forms of the condition, also known as the late infantile and juvenile forms. Children with GM1 gangliosidosis type II have normal early development, but they begin to develop signs and symptoms of the condition around the age of 18 months (late infantile form) or 5 years (juvenile form). Individuals with GM1 gangliosidosis type II experience developmental regression but usually do not have cherry-red spots, distinctive facial features, or enlarged organs. Type II usually progresses more slowly than type I, but still causes a shortened life expectancy. People with the late infantile form typically survive into mid-childhood, while those with the juvenile form may live into early adulthood. The third type of GM1 gangliosidosis is known as the adult or chronic form, and it represents the mildest end of the disease spectrum. The age at which symptoms first appear varies in GM1 gangliosidosis type III, although most affected individuals develop signs and symptoms in their teens. The characteristic features of this type include involuntary tensing of various muscles (dystonia) and abnormalities of the spinal bones (vertebrae). Life expectancy varies among people with GM1 gangliosidosis type III.
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How many people are affected by GM1 gangliosidosis ?
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GM1 gangliosidosis is estimated to occur in 1 in 100,000 to 200,000 newborns. Type I is reported more frequently than the other forms of this condition. Most individuals with type III are of Japanese descent.
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What are the genetic changes related to GM1 gangliosidosis ?
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Mutations in the GLB1 gene cause GM1 gangliosidosis. The GLB1 gene provides instructions for making an enzyme called beta-galactosidase (-galactosidase), which plays a critical role in the brain. This enzyme is located in lysosomes, which are compartments within cells that break down and recycle different types of molecules. Within lysosomes, -galactosidase helps break down several molecules, including a substance called GM1 ganglioside. GM1 ganglioside is important for normal functioning of nerve cells in the brain. Mutations in the GLB1 gene reduce or eliminate the activity of -galactosidase. Without enough functional -galactosidase, GM1 ganglioside cannot be broken down when it is no longer needed. As a result, this substance accumulates to toxic levels in many tissues and organs, particularly in the brain. Progressive damage caused by the buildup of GM1 ganglioside leads to the destruction of nerve cells in the brain, causing many of the signs and symptoms of GM1 gangliosidosis. In general, the severity of GM1 gangliosidosis is related to the level of -galactosidase activity. Individuals with higher enzyme activity levels usually have milder signs and symptoms than those with lower activity levels because they have less accumulation of GM1 ganglioside within the body. Conditions such as GM1 gangliosidosis that cause molecules to build up inside the lysosomes are called lysosomal storage disorders.
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Is GM1 gangliosidosis inherited ?
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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.
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What are the treatments for GM1 gangliosidosis ?
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These resources address the diagnosis or management of GM1 gangliosidosis: - Genetic Testing Registry: Gangliosidosis GM1 type 3 - Genetic Testing Registry: Gangliosidosis generalized GM1 type 1 - Genetic Testing Registry: Infantile GM1 gangliosidosis - Genetic Testing Registry: Juvenile GM>1< gangliosidosis 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
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What is (are) fucosidosis ?
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Fucosidosis is a condition that affects many areas of the body, especially the brain. Affected individuals have intellectual disability that worsens with age, and many develop dementia later in life. People with this condition often have delayed development of motor skills such as walking; the skills they do acquire deteriorate over time. Additional signs and symptoms of fucosidosis include impaired growth; abnormal bone development (dysostosis multiplex); seizures; abnormal muscle stiffness (spasticity); clusters of enlarged blood vessels forming small, dark red spots on the skin (angiokeratomas); distinctive facial features that are often described as "coarse"; recurrent respiratory infections; and abnormally large abdominal organs (visceromegaly). In severe cases, symptoms typically appear in infancy, and affected individuals usually live into late childhood. In milder cases, symptoms begin at age 1 or 2, and affected individuals tend to survive into mid-adulthood. In the past, researchers described two types of this condition based on symptoms and age of onset, but current opinion is that the two types are actually a single disorder with signs and symptoms that range in severity.
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How many people are affected by fucosidosis ?
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Fucosidosis is a rare condition; approximately 100 cases have been reported worldwide. This condition appears to be most prevalent in Italy, Cuba, and the southwestern United States.
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What are the genetic changes related to fucosidosis ?
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Mutations in the FUCA1 gene cause fucosidosis. The FUCA1 gene provides instructions for making an enzyme called alpha-L-fucosidase. This enzyme plays a role in the breakdown of complexes of sugar molecules (oligosaccharides) attached to certain proteins (glycoproteins) and fats (glycolipids). Alpha-L-fucosidase is responsible for cutting (cleaving) off a sugar molecule called fucose toward the end of the breakdown process. FUCA1 gene mutations severely reduce or eliminate the activity of the alpha-L-fucosidase enzyme. A lack of enzyme activity results in an incomplete breakdown of glycolipids and glycoproteins. These partially broken down compounds gradually accumulate within various cells and tissues throughout the body and cause cells to malfunction. Brain cells are particularly sensitive to the buildup of glycolipids and glycoproteins, which can result in cell death. Loss of brain cells is thought to cause the neurological symptoms of fucosidosis. Accumulation of glycolipids and glycoproteins also occurs in other organs such as the liver, spleen, skin, heart, pancreas, and kidneys, contributing to the additional symptoms of fucosidosis.
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Is fucosidosis inherited ?
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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.
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What are the treatments for fucosidosis ?
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These resources address the diagnosis or management of fucosidosis: - Genetic Testing Registry: Fucosidosis 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
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What is (are) myosin storage myopathy ?
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Myosin storage myopathy is a condition that causes muscle weakness (myopathy) that does not worsen or worsens very slowly over time. This condition is characterized by the formation of protein clumps, which contain a protein called myosin, within certain muscle fibers. The signs and symptoms of myosin storage myopathy usually become noticeable in childhood, although they can occur later. Because of muscle weakness, affected individuals may start walking later than usual and have a waddling gait, trouble climbing stairs, and difficulty lifting the arms above shoulder level. Muscle weakness also causes some affected individuals to have trouble breathing.
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How many people are affected by myosin storage myopathy ?
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Myosin storage myopathy is a rare condition. Its prevalence is unknown.
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What are the genetic changes related to myosin storage myopathy ?
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Mutations in the MYH7 gene cause myosin storage myopathy. The MYH7 gene provides instructions for making a protein known as the cardiac beta ()-myosin heavy chain. This protein is found in heart (cardiac) muscle and in type I skeletal muscle fibers, one of two types of fibers that make up the muscles that the body uses for movement. Cardiac -myosin heavy chain is the major component of the thick filament in muscle cell structures called sarcomeres. Sarcomeres, which are made up of thick and thin filaments, are the basic units of muscle contraction. The overlapping thick and thin filaments attach to each other and release, which allows the filaments to move relative to one another so that muscles can contract. Mutations in the MYH7 gene lead to the production of an altered cardiac -myosin heavy chain protein, which is thought to be less able to form thick filaments. The altered proteins accumulate in type I skeletal muscle fibers, forming the protein clumps characteristic of the disorder. It is unclear how these changes lead to muscle weakness in people with myosin storage myopathy.
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Is myosin storage myopathy inherited ?
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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.
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What are the treatments for myosin storage myopathy ?
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These resources address the diagnosis or management of myosin storage myopathy: - Genetic Testing Registry: Myosin storage 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
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What is (are) Wiskott-Aldrich syndrome ?
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Wiskott-Aldrich syndrome is characterized by abnormal immune system function (immune deficiency) and a reduced ability to form blood clots. This condition primarily affects males. Individuals with Wiskott-Aldrich syndrome have microthrombocytopenia, which is a decrease in the number and size of blood cells involved in clotting (platelets). This platelet abnormality, which is typically present from birth, can lead to easy bruising or episodes of prolonged bleeding following minor trauma. Wiskott-Aldrich syndrome causes many types of white blood cells, which are part of the immune system, to be abnormal or nonfunctional, leading to an increased risk of several immune and inflammatory disorders. Many people with this condition develop eczema, an inflammatory skin disorder characterized by abnormal patches of red, irritated skin. Affected individuals also have an increased susceptibility to infection. People with Wiskott-Aldrich syndrome are at greater risk of developing autoimmune disorders, which occur when the immune system malfunctions and attacks the body's own tissues and organs. The chance of developing some types of cancer, such as cancer of the immune system cells (lymphoma), is also greater in people with Wiskott-Aldrich syndrome.
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How many people are affected by Wiskott-Aldrich syndrome ?
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The estimated incidence of Wiskott-Aldrich syndrome is between 1 and 10 cases per million males worldwide; this condition is rarer in females.
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What are the genetic changes related to Wiskott-Aldrich syndrome ?
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Mutations in the WAS gene cause Wiskott-Aldrich syndrome. The WAS gene provides instructions for making a protein called WASP. This protein is found in all blood cells. WASP is involved in relaying signals from the surface of blood cells to the actin cytoskeleton, which is a network of fibers that make up the cell's structural framework. WASP signaling activates the cell when it is needed and triggers its movement and attachment to other cells and tissues (adhesion). In white blood cells, this signaling allows the actin cytoskeleton to establish the interaction between cells and the foreign invaders that they target (immune synapse). WAS gene mutations that cause Wiskott-Aldrich syndrome lead to a lack of any functional WASP. Loss of WASP signaling disrupts the function of the actin cytoskeleton in developing blood cells. White blood cells that lack WASP have a decreased ability to respond to their environment and form immune synapses. As a result, white blood cells are less able to respond to foreign invaders, causing many of the immune problems related to Wiskott-Aldrich syndrome. Similarly, a lack of functional WASP in platelets impairs their development, leading to reduced size and early cell death.
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Is Wiskott-Aldrich syndrome inherited ?
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This condition is inherited in an X-linked 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 gene in each cell may or may not cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of the gene in each cell causes the disorder. In most cases of X-linked inheritance, males experience more severe symptoms of the disorder than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
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What are the treatments for Wiskott-Aldrich syndrome ?
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These resources address the diagnosis or management of Wiskott-Aldrich syndrome: - Gene Review: Gene Review: WAS-Related Disorders - Genetic Testing Registry: Wiskott-Aldrich syndrome - MedlinePlus Encyclopedia: Thrombocytopenia - National Marrow Donor Program - Rare Disease Clinical Research Network: Primary Immune Deficiency Treatment Consortium 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
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What is (are) microphthalmia with linear skin defects syndrome ?
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Microphthalmia with linear skin defects syndrome is a disorder that mainly affects females. In people with this condition, one or both eyes may be very small or poorly developed (microphthalmia). Affected individuals also typically have unusual linear skin markings on the head and neck. These markings follow the paths along which cells migrate as the skin develops before birth (lines of Blaschko). The skin defects generally improve over time and leave variable degrees of scarring. The signs and symptoms of microphthalmia with linear skin defects syndrome vary widely, even among affected individuals within the same family. In addition to the characteristic eye problems and skin markings, this condition can cause abnormalities in the brain, heart, and genitourinary system. A hole in the muscle that separates the abdomen from the chest cavity (the diaphragm), which is called a diaphragmatic hernia, may occur in people with this disorder. Affected individuals may also have short stature and fingernails and toenails that do not grow normally (nail dystrophy).
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How many people are affected by microphthalmia with linear skin defects syndrome ?
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The prevalence of microphthalmia with linear skin defects syndrome is unknown. More than 50 affected individuals have been identified.
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