bowang0911/MedQuAD huggingface dataset:
Multiple sclerosis is a condition characterized by areas of damage (lesions) on the brain and spinal cord. These lesions are associated with destruction of the covering that protects nerves and promotes the efficient transmission of nerve impulses (the myelin sheath) and damage to nerve cells. Multiple sclerosis is considered an autoimmune disorder; autoimmune disorders occur when the immune system malfunctions and attacks the body's own tissues and organs, in this case tissues of the nervous system.  Multiple sclerosis usually begins in early adulthood, between ages 20 and 40. The symptoms vary widely, and affected individuals can experience one or more effects of nervous system damage. Multiple sclerosis often causes sensory disturbances in the limbs, including a prickling or tingling sensation (paresthesia), numbness, pain, and itching. Some people experience Lhermitte sign, which is an electrical shock-like sensation that runs down the back and into the limbs. This sensation usually occurs when the head is bent forward. Problems with muscle control are common in people with multiple sclerosis. Affected individuals may have tremors, muscle stiffness (spasticity), exaggerated reflexes (hyperreflexia), weakness or partial paralysis of the muscles of the limbs, difficulty walking, or poor bladder control. Multiple sclerosis is also associated with vision problems, such as blurred or double vision or partial or complete vision loss. Infections that cause fever can make the symptoms worse.  There are several forms of multiple sclerosis: relapsing-remitting MS, secondary progressive MS, primary progressive MS, and progressive relapsing MS. The most common is the relapsing-remitting form, which affects approximately 80 percent of people with multiple sclerosis. Individuals with this form of the condition have periods during which they experience symptoms, called clinical attacks, followed by periods without any symptoms (remission). The triggers of clinical attacks and remissions are unknown. After about 10 years, relapsing-remitting MS usually develops into another form of the disorder called secondary progressive MS. In this form, there are no remissions, and symptoms of the condition continually worsen.  Primary progressive MS is the next most common form, affecting approximately 10 to 20 percent of people with multiple sclerosis. This form is characterized by constant symptoms that worsen over time, with no clinical attacks or remissions. Primary progressive MS typically begins later than the other forms, around age 40.  Progressive relapsing MS is a rare form of multiple sclerosis that initially appears like primary progressive MS, with constant symptoms. However, people with progressive relapsing MS also experience clinical attacks of more severe symptoms.
An estimated 1.1 to 2.5 million people worldwide have multiple sclerosis. Although the reason is unclear, this condition is more common in regions that are farther away from the equator. In Canada, parts of the northern United States, western and northern Europe, Russia, and southeastern Australia, the condition affects approximately 1 in 2,000 to 2,400 people. It is less common closer to the equator, such as in Asia, sub-Saharan Africa, and parts of South America, where about 1 in 20,000 people are affected. For unknown reasons, most forms of multiple sclerosis affect women twice as often as men; however, women and men are equally affected by primary progressive MS.
Although the cause of multiple sclerosis is unknown, variations in dozens of genes are thought to be involved in multiple sclerosis risk. Changes in the HLA-DRB1 gene are the strongest genetic risk factors for developing multiple sclerosis. Other factors associated with an increased risk of developing multiple sclerosis include changes in the IL7R gene and environmental factors, such as exposure to the Epstein-Barr virus, low levels of vitamin D, and smoking.  The HLA-DRB1 gene belongs to a family of genes called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders (such as viruses and bacteria). Each HLA gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign proteins. Variations in several HLA genes have been associated with increased multiple sclerosis risk, but one particular variant of the HLA-DRB1 gene, called HLA-DRB1*15:01, is the most strongly linked genetic factor.  The IL7R gene provides instructions for making one piece of two different receptor proteins: the interleukin 7 (IL-7) receptor and the thymic stromal lymphopoietin (TSLP) receptor. Both receptors are embedded in the cell membrane of immune cells. These receptors stimulate signaling pathways that induce the growth and division (proliferation) and survival of immune cells. The genetic variation involved in multiple sclerosis leads to production of an IL-7 receptor that is not embedded in the cell membrane but is instead found inside the cell. It is unknown if this variation affects the TSLP receptor.  Because the HLA-DRB1 and IL-7R genes are involved in the immune system, changes in either might be related to the autoimmune response that damages the myelin sheath and nerve cells and leads to the signs and symptoms of multiple sclerosis. However, it is unclear exactly what role variations in either gene plays in development of the condition.
These resources address the diagnosis or management of multiple sclerosis:  - Gene Review: Gene Review: Multiple Sclerosis Overview  - Multiple Sclerosis Association of America: Treatments for MS  - Multiple Sclerosis International Federation: About MS--Diagnosis  - National Multiple Sclerosis Society: Diagnosing Tools   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
Retinitis pigmentosa is a group of related eye disorders that cause progressive vision loss. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with retinitis pigmentosa, vision loss occurs as the light-sensing cells of the retina gradually deteriorate.  The first sign of retinitis pigmentosa is usually a loss of night vision, which becomes apparent in childhood. Problems with night vision can make it difficult to navigate in low light. Later, the disease causes blind spots to develop in the side (peripheral) vision. Over time, these blind spots merge to produce tunnel vision. The disease progresses over years or decades to affect central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. In adulthood, many people with retinitis pigmentosa become legally blind.  The signs and symptoms of retinitis pigmentosa are most often limited to vision loss. When the disorder occurs by itself, it is described as nonsyndromic. Researchers have identified several major types of nonsyndromic retinitis pigmentosa, which are usually distinguished by their pattern of inheritance: autosomal dominant, autosomal recessive, or X-linked.  Less commonly, retinitis pigmentosa occurs as part of syndromes that affect other organs and tissues in the body. These forms of the disease are described as syndromic. The most common form of syndromic retinitis pigmentosa is Usher syndrome, which is characterized by the combination of vision loss and hearing loss beginning early in life. Retinitis pigmentosa is also a feature of several other genetic syndromes, including Bardet-Biedl syndrome; Refsum disease; and neuropathy, ataxia, and retinitis pigmentosa (NARP).
Mutations in more than 60 genes are known to cause nonsyndromic retinitis pigmentosa. More than 20 of these genes are associated with the autosomal dominant form of the disorder. Mutations in the RHO gene are the most common cause of autosomal dominant retinitis pigmentosa, accounting for 20 to 30 percent of all cases. At least 35 genes have been associated with the autosomal recessive form of the disorder. The most common of these is USH2A; mutations in this gene are responsible for 10 to 15 percent of all cases of autosomal recessive retinitis pigmentosa. Changes in at least six genes are thought to cause the X-linked form of the disorder. Together, mutations in the RPGR and RP2 genes account for most cases of X-linked retinitis pigmentosa.  The genes associated with retinitis pigmentosa play essential roles in the structure and function of specialized light receptor cells (photoreceptors) in the retina. The retina contains two types of photoreceptors, rods and cones. Rods are responsible for vision in low light, while cones provide vision in bright light, including color vision.  Mutations in any of the genes responsible for retinitis pigmentosa lead to a gradual loss of rods and cones in the retina. The progressive degeneration of these cells causes the characteristic pattern of vision loss that occurs in people with retinitis pigmentosa. Rods typically break down before cones, which is why night vision impairment is usually the first sign of the disorder. Daytime vision is disrupted later, as both rods and cones are lost.  Some of the genes associated with retinitis pigmentosa are also associated with other eye diseases, including a condition called cone-rod dystrophy. Cone-rod dystrophy has signs and symptoms similar to those of retinitis pigmentosa. However, cone-rod dystrophy is characterized by deterioration of the cones first, followed by the rods, so daylight and color vision are affected before night vision.
Retinitis pigmentosa often has an autosomal dominant inheritance pattern, which means one copy of an altered gene in each cell is sufficient to cause the disorder. Most people with autosomal dominant retinitis pigmentosa have an affected parent and other family members with the disorder.  Retinitis pigmentosa can also have an autosomal recessive pattern of inheritance, which means both copies of a gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.  This condition can also be inherited in an X-linked pattern. The genes associated with X-linked retinitis pigmentosa 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), mutations usually have to occur in both copes of the gene to cause the disorder. However, at least 20 percent of females who carry only one mutated copy of the gene develop retinal degeneration and associated vision loss. In most cases, 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.  In 10 to 40 percent of all cases of retinitis pigmentosa, only one person in a family is affected. In these families, the disorder is described as simplex. It can be difficult to determine the inheritance pattern of simplex cases because affected individuals may have no affected relatives or may be unaware of other family members with the disease. Simplex cases can also result from a new gene mutation that is not present in other family members.
These resources address the diagnosis or management of retinitis pigmentosa:  - American Foundation for the Blind: Living with Vision Loss  - Foundation Fighting Blindness: Treatment of Retinitis Pigmentosa  - Gene Review: Gene Review: Retinitis Pigmentosa Overview  - Genetic Testing Registry: Retinitis pigmentosa  - RP Fighting Blindness: Treatment of Retinitis Pigmentosa   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
Stormorken syndrome is a rare condition that affects many body systems. Affected individuals usually have thrombocytopenia, in which there are abnormally low numbers of blood cells called platelets. Platelets are involved in normal blood clotting; a shortage of platelets typically results in easy bruising and abnormal bleeding. In addition, affected individuals often have a muscle disorder, called tubular aggregate myopathy, that leads to muscle weakness. Another feature of Stormorken syndrome is permanent constriction of the pupils of the eyes (miosis), which may be caused by abnormalities in the muscles that control the size of the pupils. Other features include lack of a functioning spleen (asplenia), scaly skin (ichthyosis), headaches, and difficulty with reading and spelling (dyslexia).
Stormorken syndrome is caused by a mutation in the STIM1 gene. The protein produced from this gene is involved in controlling the entry of positively charged calcium atoms (calcium ions) into cells. The STIM1 protein recognizes when calcium ion levels are low and stimulates the flow of ions into the cell through special channels in the cell membrane called calcium-release activated calcium (CRAC) channels. The flow of calcium ions through CRAC channels triggers signaling within cells that helps control gene activity, cell growth and division, and immune function.  The STIM1 gene mutation involved in Stormorken syndrome leads to production of a STIM1 protein that is constantly turned on (constitutively active), which means it continually stimulates calcium ion entry through CRAC channels regardless of ion levels. Researchers suggest that the abnormal ion flow in platelets causes the cells to die earlier than usual, leading to thrombocytopenia and bleeding problems in people with Stormorken syndrome. It is unknown how constitutively active STIM1 leads to the other features of the disorder.
Down syndrome is a chromosomal condition that is associated with intellectual disability, a characteristic facial appearance, and weak muscle tone (hypotonia) in infancy. All affected individuals experience cognitive delays, but the intellectual disability is usually mild to moderate.  People with Down syndrome may have a variety of birth defects. About half of all affected children are born with a heart defect. Digestive abnormalities, such as a blockage of the intestine, are less common.  Individuals with Down syndrome have an increased risk of developing several medical conditions. These include gastroesophageal reflux, which is a backflow of acidic stomach contents into the esophagus, and celiac disease, which is an intolerance of a wheat protein called gluten. About 15 percent of people with Down syndrome have an underactive thyroid gland (hypothyroidism). The thyroid gland is a butterfly-shaped organ in the lower neck that produces hormones. Individuals with Down syndrome also have an increased risk of hearing and vision problems. Additionally, a small percentage of children with Down syndrome develop cancer of blood-forming cells (leukemia).  Delayed development and behavioral problems are often reported in children with Down syndrome. Affected individuals' speech and language develop later and more slowly than in children without Down syndrome, and affected individuals' speech may be more difficult to understand. Behavioral issues can include attention problems, obsessive/compulsive behavior, and stubbornness or tantrums. A small percentage of people with Down syndrome are also diagnosed with developmental conditions called autism spectrum disorders, which affect communication and social interaction.  People with Down syndrome often experience a gradual decline in thinking ability (cognition) as they age, usually starting around age 50. Down syndrome is also associated with an increased risk of developing Alzheimer disease, a brain disorder that results in a gradual loss of memory, judgment, and ability to function. Approximately half of adults with Down syndrome develop Alzheimer disease. Although Alzheimer disease is usually a disorder that occurs in older adults, people with Down syndrome usually develop this condition in their fifties or sixties.
Most cases of Down syndrome result from trisomy 21, which means each cell in the body has three copies of chromosome 21 instead of the usual two copies.  Less commonly, Down syndrome occurs when part of chromosome 21 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) in a parent or very early in fetal development. Affected people have two normal copies of chromosome 21 plus extra material from chromosome 21 attached to another chromosome, resulting in three copies of genetic material from chromosome 21. Affected individuals with this genetic change are said to have translocation Down syndrome.  A very small percentage of people with Down syndrome have an extra copy of chromosome 21 in only some of the body's cells. In these people, the condition is called mosaic Down syndrome.  Researchers believe that having extra copies of genes on chromosome 21 disrupts the course of normal development, causing the characteristic features of Down syndrome and the increased risk of health problems associated with this condition.
Most cases of Down syndrome are not inherited. When the condition is caused by trisomy 21, the chromosomal abnormality occurs as a random event during the formation of reproductive cells in a parent. The abnormality usually occurs in egg cells, but it occasionally occurs in sperm cells. An error in cell division called nondisjunction results in a reproductive cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 21. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 21 in each of the body's cells.  People with translocation Down syndrome can inherit the condition from an unaffected parent. The parent carries a rearrangement of genetic material between chromosome 21 and another chromosome. This rearrangement is called a balanced translocation. No genetic material is gained or lost in a balanced translocation, so these chromosomal changes usually do not cause any health problems. However, as this translocation is passed to the next generation, it can become unbalanced. People who inherit an unbalanced translocation involving chromosome 21 may have extra genetic material from chromosome 21, which causes Down syndrome.  Like trisomy 21, mosaic Down syndrome is not inherited. It occurs as a random event during cell division early in fetal development. As a result, some of the body's cells have the usual two copies of chromosome 21, and other cells have three copies of this chromosome.
These resources address the diagnosis or management of Down syndrome:  - GeneFacts: Down Syndrome: Diagnosis  - GeneFacts: Down Syndrome: Management  - Genetic Testing Registry: Complete trisomy 21 syndrome  - National Down Syndrome Congress: Health Care  - National Down Syndrome Congress: Speech and Language  - National Down Syndrome Society: Health Care  - National Down Syndrome Society: Therapies and Development   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
Desmosterolosis is a condition that is characterized by neurological problems, such as brain abnormalities and developmental delay, and can also include other signs and symptoms.  Children with desmosterolosis have delayed speech and motor skills (such as sitting and walking). Later in childhood, some affected individuals are able to walk with support; verbal communication is often limited to a few words or phrases. Common brain abnormalities in desmosterolosis include malformation of the tissue that connects the left and right halves of the brain (the corpus callosum) and loss of white matter, which consists of nerve fibers covered by a fatty substance called myelin.  People with desmosterolosis commonly have muscle stiffness (spasticity) and stiff, rigid joints (arthrogryposis) affecting their hands and feet. Other features seen in some affected individuals include short stature, abnormal head size (either larger or smaller than normal), a small lower jaw (micrognathia), an opening in the roof of the mouth (cleft palate), involuntary eye movements (nystagmus) or eyes that do not look in the same direction (strabismus), heart defects, and seizures.
Desmosterolosis is caused by mutations in the DHCR24 gene. This gene provides instructions for making an enzyme called 24-dehydrocholesterol reductase, which is involved in the production (synthesis) of cholesterol. Cholesterol is a waxy, fat-like substance that can be obtained from foods that come from animals (particularly egg yolks, meat, poultry, fish, and dairy products). It can also be produced in various tissues in the body. For example, the brain cannot access the cholesterol that comes from food, so brain cells must produce their own. Cholesterol is necessary for normal embryonic development and has important functions both before and after birth.  DHCR24 gene mutations lead to the production of 24-dehydrocholesterol reductase with reduced activity. As a result, there is a decrease in cholesterol production. Because the brain relies solely on cellular production for cholesterol, it is most severely affected. Without adequate cholesterol, cell membranes are not formed properly and nerve cells are not protected by myelin, leading to the death of these cells. In addition, a decrease in cholesterol production has more severe effects before birth than during other periods of development because of the rapid increase in cell number that takes place. Disruption of normal cell formation before birth likely accounts for the additional developmental abnormalities of desmosterolosis.
Kufs disease is a condition that primarily affects the nervous system, causing problems with movement and intellectual function that worsen over time. The signs and symptoms of Kufs disease typically appear around age 30, but they can develop anytime between adolescence and late adulthood.  Two types of Kufs disease have been described: type A and type B. The two types are differentiated by their genetic cause, pattern of inheritance, and certain signs and symptoms. Type A is characterized by a combination of seizures and uncontrollable muscle jerks (myoclonic epilepsy), a decline in intellectual function (dementia), impaired muscle coordination (ataxia), involuntary movements such as tremors or tics, and speech difficulties (dysarthria). Kufs disease type B shares many features with type A, but it is distinguished by changes in personality and is not associated with myoclonic epilepsy or dysarthria.  The signs and symptoms of Kufs disease worsen over time, and affected individuals usually survive about 15 years after the disorder begins.  Kufs disease is one of a group of disorders known as neuronal ceroid lipofuscinoses (NCLs), which are also known as Batten disease. These disorders affect the nervous system and typically cause progressive problems with vision, movement, and thinking ability. Kufs disease, however, does not affect vision. The different types of NCLs are distinguished by the age at which signs and symptoms first appear.