bowang0911/MedQuAD huggingface dataset:
The SLC46A1 gene provides instructions for making a protein called the proton-coupled folate transporter (PCFT). PCFT is important for normal functioning of intestinal epithelial cells, which are cells that line the walls of the intestine. These cells have fingerlike projections called microvilli that absorb nutrients from food as it passes through the intestine. Based on their appearance, groups of these microvilli are known collectively as the brush border. PCFT is involved in the process of using energy to move folates across the brush border membrane, a mechanism called active transport. It is also involved in the transport of folates between the brain and the fluid that surrounds it (cerebrospinal fluid).  Mutations in the SLC46A1 gene result in a PCFT protein that has little or no activity. In some cases the mutated protein is not transported to the cell membrane, and so it is unable to perform its function. A lack of functional PCFT impairs the body's ability to absorb folates from food, resulting in the signs and symptoms of hereditary folate malabsorption.
These resources address the diagnosis or management of hereditary folate malabsorption:  - Gene Review: Gene Review: Hereditary Folate Malabsorption  - Genetic Testing Registry: Congenital defect of folate absorption  - MedlinePlus Encyclopedia: Folate  - MedlinePlus Encyclopedia: Folate Deficiency  - MedlinePlus Encyclopedia: Folate-Deficiency Anemia  - MedlinePlus Encyclopedia: Malabsorption   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
MECP2 duplication syndrome is a condition that occurs almost exclusively in males and is characterized by moderate to severe intellectual disability. Most people with this condition also have weak muscle tone in infancy, feeding difficulties, poor or absent speech, seizures that may not improve with treatment, or muscle stiffness (spasticity). Individuals with MECP2 duplication syndrome have delayed development of motor skills such as sitting and walking. Some affected individuals experience the loss of previously acquired skills (developmental regression). Approximately one third of people with this condition cannot walk without assistance. Many individuals with MECP2 duplication syndrome have recurrent respiratory tract infections. These respiratory infections are a major cause of death in affected individuals, with almost half succumbing by age 25.
MECP2 duplication syndrome is caused by a genetic change in which there is an extra copy of the MECP2 gene in each cell. This extra copy of the MECP2 gene is caused by a duplication of genetic material on the long (q) arm of the X chromosome. The size of the duplication varies from 100,000 to 900,000 DNA building blocks (base pairs), also written as 100 to 900 kilobases (kb). The MECP2 gene is always included in this duplication, and other genes may be involved, depending on the size of the duplicated segment. Extra copies of these other genes do not seem to affect the severity of the condition, because people with larger duplications have signs and symptoms that are similar to people with smaller duplications.  The MECP2 gene provides instructions for making a protein called MeCP2 that is critical for normal brain function. Researchers believe that this protein has several functions, including regulating other genes in the brain by switching them off when they are not needed. An extra copy of the MECP2 gene leads to the production of excess MeCP2 protein, which is unable to properly regulate the expression of other genes. The misregulation of gene expression in the brain results in abnormal nerve cell (neuronal) function. These neuronal abnormalities cause irregular brain activity, leading to the signs and symptoms of MECP2 duplication syndrome.
MECP2 duplication syndrome 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 males (who have only one X chromosome), a duplication of the only copy of the MECP2 gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a duplication of one of the two copies of the gene typically does not cause the disorder. Females usually do not have signs and symptoms of MECP2 duplication syndrome because the X chromosome that contains the duplication may be turned off (inactive) due to a process called X-inactivation.  Early in embryonic development in females, one of the two X chromosomes is permanently inactivated in somatic cells (cells other than egg and sperm cells). X-inactivation ensures that females, like males, have only one active copy of the X chromosome in each body cell. Usually X-inactivation occurs randomly, such that each X chromosome is active in about half of the body cells. Sometimes X-inactivation is not random, and one X chromosome is active in more than half of cells. When X-inactivation does not occur randomly, it is called skewed X-inactivation.  Research shows that females with an MECP2 gene duplication have skewed X-inactivation, which results in the inactivation of the X chromosome containing the duplication in most cells of the body. This skewed X inactivation ensures that only the chromosome with the normal MECP2 gene is expressed. This skewed X-inactivation is why females with an MECP2 gene duplication typically do not have any features related to the additional genetic material.
These resources address the diagnosis or management of MECP2 duplication syndrome:  - Cincinnati Children's Hospital: MECP2-Related Disorders  - Cleveland Clinic: Spasticity  - Gene Review: Gene Review: MECP2 Duplication Syndrome  - Genetic Testing Registry: MECP2 duplication syndrome   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care
Paroxysmal nocturnal hemoglobinuria is an acquired disorder that leads to the premature death and impaired production of blood cells. The disorder affects red blood cells (erythrocytes), which carry oxygen; white blood cells (leukocytes), which protect the body from infection; and platelets (thrombocytes), which are involved in blood clotting. Paroxysmal nocturnal hemoglobinuria affects both sexes equally, and can occur at any age, although it is most often diagnosed in young adulthood.  People with paroxysmal nocturnal hemoglobinuria have sudden, recurring episodes of symptoms (paroxysmal symptoms), which may be triggered by stresses on the body, such as infections or physical exertion. During these episodes, red blood cells are prematurely destroyed (hemolysis). Affected individuals may pass dark-colored urine due to the presence of hemoglobin, the oxygen-carrying protein in blood. The abnormal presence of hemoglobin in the urine is called hemoglobinuria. In many, but not all cases, hemoglobinuria is most noticeable in the morning, upon passing urine that has accumulated in the bladder during the night (nocturnal).  The premature destruction of red blood cells results in a deficiency of these cells in the blood (hemolytic anemia), which can cause signs and symptoms such as fatigue, weakness, abnormally pale skin (pallor), shortness of breath, and an increased heart rate. People with paroxysmal nocturnal hemoglobinuria may also be prone to infections due to a deficiency of white blood cells.  Abnormal platelets associated with paroxysmal nocturnal hemoglobinuria can cause problems in the blood clotting process. As a result, people with this disorder may experience abnormal blood clotting (thrombosis), especially in large abdominal veins; or, less often, episodes of severe bleeding (hemorrhage).  Individuals with paroxysmal nocturnal hemoglobinuria are at increased risk of developing cancer in blood-forming cells (leukemia).  In some cases, people who have been treated for another blood disease called aplastic anemia may develop paroxysmal nocturnal hemoglobinuria.
Mutations in the PIGA gene cause paroxysmal nocturnal hemoglobinuria.  The PIGA gene provides instructions for making a protein called phosphatidylinositol glycan class A. This protein takes part in a series of steps that produce a molecule called GPI anchor. GPI anchor attaches many different proteins to the cell membrane, thereby ensuring that these proteins are available when needed at the surface of the cell.  Some gene mutations are acquired during a person's lifetime and are present only in certain cells. These changes, which are called somatic mutations, are not inherited. In people with paroxysmal nocturnal hemoglobinuria, somatic mutations of the PIGA gene occur in blood-forming cells called hematopoietic stem cells, which are found mainly in the bone marrow. These mutations result in the production of abnormal blood cells. As the abnormal hematopoietic stem cells multiply, increasing numbers of abnormal blood cells are formed, alongside normal blood cells produced by normal hematopoietic stem cells.  The premature destruction of red blood cells seen in paroxysmal nocturnal hemoglobinuria is caused by a component of the immune system called complement. Complement consists of a group of proteins that work together to destroy foreign invaders such as bacteria and viruses. To protect the individual's own cells from being destroyed, this process is tightly controlled by complement-regulating proteins. Complement-regulating proteins normally protect red blood cells from destruction by complement. In people with paroxysmal nocturnal hemoglobinuria, however, abnormal red blood cells are missing two important complement-regulating proteins that need the GPI anchor protein to attach them to the cell membrane. These red blood cells are prematurely destroyed, leading to hemolytic anemia.  Research suggests that certain abnormal white blood cells that are also part of the immune system may mistakenly attack normal blood-forming cells, in a malfunction called an autoimmune process. In addition, abnormal hematopoietic stem cells in people with paroxysmal nocturnal hemoglobinuria may be less susceptible than normal cells to a process called apoptosis, which causes cells to self-destruct when they are damaged or unneeded. These features of the disorder may increase the proportion of abnormal blood cells in the body. The proportion of abnormal blood cells affects the severity of the signs and symptoms of paroxysmal nocturnal hemoglobinuria, including the risk of hemoglobinuria and thrombosis.
These resources address the diagnosis or management of paroxysmal nocturnal hemoglobinuria:  - Duke University School of Medicine: Hemostasis & Thrombosis Center  - Genetic Testing Registry: Paroxysmal nocturnal hemoglobinuria  - MedlinePlus Encyclopedia: Paroxysmal nocturnal hemoglobinuria (PNH)  - Memorial Sloan-Kettering Cancer Center   These resources from MedlinePlus offer information about the diagnosis and management of various health conditions:  - Diagnostic Tests  - Drug Therapy  - Surgery and Rehabilitation  - Genetic Counseling   - Palliative Care
Glycine encephalopathy, which is also known as nonketotic hyperglycinemia or NKH, is a genetic disorder characterized by abnormally high levels of a molecule called glycine. This molecule is an amino acid, which is a building block of proteins. Glycine also acts as a neurotransmitter, which is a chemical messenger that transmits signals in the brain. Glycine encephalopathy is caused by the shortage of an enzyme that normally breaks down glycine in the body. A lack of this enzyme allows excess glycine to build up in tissues and organs, particularly the brain, leading to serious medical problems.  The most common form of glycine encephalopathy, called the classical type, appears shortly after birth. Affected infants experience a progressive lack of energy (lethargy), feeding difficulties, weak muscle tone (hypotonia), abnormal jerking movements, and life-threatening problems with breathing. Most children who survive these early signs and symptoms develop profound intellectual disability and seizures that are difficult to treat. For unknown reasons, affected males are more likely to survive and have less severe developmental problems than affected females.  Researchers have identified several other types of glycine encephalopathy with variable signs and symptoms. The most common of these atypical types is called the infantile form. Children with this condition develop normally until they are about 6 months old, when they experience delayed development and may begin having seizures. As they get older, many develop intellectual disability, abnormal movements, and behavioral problems. Other atypical types of glycine encephalopathy appear later in childhood or adulthood and cause a variety of medical problems that primarily affect the nervous system.  Rarely, the characteristic features of classical glycine encephalopathy improve with time. These cases are classified as transient glycine encephalopathy. In this form of the condition, glycine levels decrease to normal or near-normal after being very high at birth. Many children with temporarily high glycine levels go on to develop normally and experience few long-term medical problems. Intellectual disability and seizures occur in some affected individuals, however, even after glycine levels decrease.
Mutations in the AMT and GLDC genes cause glycine encephalopathy.  About 80 percent of cases of glycine encephalopathy result from mutations in the GLDC gene, while AMT mutations cause 10 percent to 15 percent of all cases. In a small percentage of affected individuals, the cause of this condition is unknown.  The AMT and GLDC genes provide instructions for making proteins that work together as part of a larger enzyme complex. This complex, known as glycine cleavage enzyme, is responsible for breaking down glycine into smaller pieces. Mutations in either the AMT or GLDC gene prevent the complex from breaking down glycine properly. When glycine cleavage enzyme is defective, excess glycine can build up to toxic levels in the body's organs and tissues. Damage caused by harmful amounts of this molecule in the brain and spinal cord is responsible for the intellectual disability, seizures, and breathing difficulties characteristic of glycine encephalopathy.
These resources address the diagnosis or management of glycine encephalopathy:  - Baby's First Test  - Gene Review: Gene Review: Glycine Encephalopathy  - Genetic Testing Registry: Non-ketotic hyperglycinemia   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
Spinocerebellar ataxia type 6 (SCA6) is a condition characterized by progressive problems with movement. People with this condition initially experience problems with coordination and balance (ataxia). Other early signs and symptoms of SCA6 include speech difficulties, involuntary eye movements (nystagmus), and double vision. Over time, individuals with SCA6 may develop loss of coordination in their arms, tremors, and uncontrolled muscle tensing (dystonia).  Signs and symptoms of SCA6 typically begin in a person's forties or fifties but can appear anytime from childhood to late adulthood. Most people with this disorder require wheelchair assistance by the time they are in their sixties.
Mutations in the CACNA1A gene cause SCA6. The CACNA1A gene provides instructions for making a protein that forms a part of some calcium channels. These channels transport positively charged calcium atoms (calcium ions) across cell membranes. The movement of these ions is critical for normal signaling between nerve cells (neurons) in the brain and other parts of the nervous system. The CACNA1A gene provides instructions for making one part (the alpha-1 subunit) of a calcium channel called CaV2.1. CaV2.1 channels play an essential role in communication between neurons in the brain.  The CACNA1A gene mutations that cause SCA6 involve a DNA segment known as a CAG trinucleotide repeat. This segment is made up of a series of three DNA building blocks (cytosine, adenine, and guanine) that appear multiple times in a row. Normally, the CAG segment is repeated 4 to 18 times within the gene. In people with SCA6, the CAG segment is repeated 20 to 33 times. People with 20 repeats tend to experience signs and symptoms of SCA6 beginning in late adulthood, while people with a larger number of repeats usually have signs and symptoms from mid-adulthood.  An increase in the length of the CAG segment leads to the production of an abnormally long version of the alpha-1 subunit. This version of the subunit alters the location and function of the CaV2.1 channels. Normally the alpha-1 subunit is located within the cell membrane; the abnormal subunit is found in the cell membrane as well as in the fluid inside cells (cytoplasm), where it clusters together and forms clumps (aggregates). The effect these aggregates have on cell functioning is unknown. The lack of normal calcium channels in the cell membrane impairs cell communication between neurons in the brain. Diminished cell communication leads to cell death. Cells within the cerebellum, which is the part of the brain that coordinates movement, are particularly sensitive to the accumulation of these aggregates. Over time, a loss of cells in the cerebellum causes the movement problems characteristic of SCA6.
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.  In most cases, an affected person has one parent with the condition.  As the altered CACNA1A gene is passed down from one generation to the next, the length of the CAG trinucleotide repeat often slightly increases. A larger number of repeats is usually associated with an earlier onset of signs and symptoms. This phenomenon is called anticipation.
These resources address the diagnosis or management of SCA6:  - Gene Review: Gene Review: Spinocerebellar Ataxia Type 6  - Genetic Testing Registry: Spinocerebellar ataxia 6   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
LAMA2-related muscular dystrophy is a disorder that causes weakness and wasting (atrophy) of muscles used for movement (skeletal muscles). This condition generally appears in one of two ways: as a severe, early-onset type or a milder, late-onset form.  Early-onset LAMA2-related muscular dystrophy is apparent at birth or within the first few months of life. It is considered part of a class of muscle disorders called congenital muscular dystrophies and is sometimes called congenital muscular dystrophy type 1A. Affected infants have severe muscle weakness, lack of muscle tone (hypotonia), little spontaneous movement, and joint deformities (contractures). Weakness of the muscles in the face and throat can result in feeding difficulties and an inability to grow and gain weight at the expected rate (failure to thrive). Hypotonia also affects the muscles used for breathing, which causes a weak cry and breathing problems that can lead to frequent, potentially life-threatening lung infections.  As affected children grow, they often develop an abnormal, gradually worsening side-to-side curvature of the spine (scoliosis) and inward curvature of the back (lordosis). Children with early-onset LAMA2-related muscular dystrophy usually do not learn to walk unassisted. Speech problems may result from weakness of the facial muscles and tongue, but intelligence is usually normal. Heart problems and seizures occasionally occur in early-onset LAMA2-related muscular dystrophy. Because of the serious health problems that occur in this form of the disorder, many affected individuals do not survive past adolescence.  Late-onset LAMA2-related muscular dystrophy occurs later in childhood or in adulthood. Signs and symptoms of this form of the disorder are milder than in the early-onset type and are similar to those of a group of muscle disorders classified as limb-girdle muscular dystrophies. In late-onset LAMA2-related muscular dystrophy, the muscles most affected are those closest to the body (proximal muscles), specifically the muscles of the shoulders, upper arms, pelvic area, and thighs. Children with late-onset LAMA2-related muscular dystrophy sometimes have delayed development of motor skills such as walking, but generally achieve the ability to walk without assistance. Over time, they may develop rigidity of the back, joint contractures, scoliosis, and breathing problems. However, most affected individuals retain the ability to walk and climb stairs, and life expectancy and intelligence are usually not affected in late-onset LAMA2-related muscular dystrophy.
As its name suggests, LAMA2-related muscular dystrophy is caused by mutations in the LAMA2 gene. This gene provides instructions for making a part (subunit) of certain members of a protein family called laminins. Laminin proteins are made of three different subunits called alpha, beta, and gamma. There are several forms of each subunit, and each form is produced from instructions carried by a different gene. The LAMA2 gene provides instructions for the alpha-2 subunit. This subunit is found in the laminin 2 protein, also known as merosin; it is also part of another laminin protein called laminin 4.  Laminins are found in an intricate lattice of proteins and other molecules that forms in the spaces between cells (the extracellular matrix). Laminin 2 and laminin 4 play a particularly important role in the muscles used for movement (skeletal muscles). The laminins attach (bind) to other proteins in the extracellular matrix and in the membrane of muscle cells, which helps maintain the stability of muscle fibers.  Most LAMA2 gene mutations that cause the severe, early-onset form of LAMA2-related muscular dystrophy result in the absence of functional laminin alpha-2 subunit. Mutations that cause the milder, later-onset form usually result in a reduction (deficiency) of functional laminin alpha-2 subunit. Deficiency or absence of the laminin alpha-2 subunit results in a corresponding lack of laminin 2 and laminin 4, reducing the strength and stability of muscle tissue and leading to the signs and symptoms of LAMA2-related muscular dystrophy.
These resources address the diagnosis or management of LAMA2-related muscular dystrophy:  - Boston Children's Hospital: Treatment and Care for Muscular Dystrophy  - Gene Review: Gene Review: LAMA2-Related Muscular Dystrophy  - Genetic Testing Registry: Congenital muscular dystrophy due to partial LAMA2 deficiency  - Genetic Testing Registry: Merosin deficient congenital muscular dystrophy  - Kennedy Krieger Institute: Center for Genetic Muscle Disorders   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