Alzheimer's disease is a progressive neurologic disorder that causes the brain to shrink (atrophy) and brain cells to die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social ski...

Alzheimer's disease is a progressive neurologic disorder that causes the brain to shrink (atrophy) and brain cells to die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social ski...

Amaurosis-hypertrichosis syndrome is a rare genetic disorder characterized by a combination of vision loss (amaurosis) and excessive hair growth (hypertrichosis). It is caused by a mutation in the GNAQ gene, which is responsible for the production...

Amblyopia, also known as lazy eye, is a vision development disorder in which an eye fails to achieve normal visual acuity, even with prescription eyeglasses or contact lenses. It is the most common cause of vision problems in children. Amblyopia i...

Amelia of lower limb is a congenital disorder in which one or more of the bones in the lower limb are missing. It is a rare condition that affects the development of the lower limb, usually the thighbone (femur) or the shinbone (tibia)....

Amelia of upper limb is a congenital disorder in which one or more of the bones in the arm or hand are missing. It is a rare condition that affects about 1 in every 30,000 births. Symptoms may include a short arm, a hand with fewer than five finge...

Amelo-onycho-hypohidrotic syndrome, also known as Hay-Wells syndrome, is a rare genetic disorder that affects the development of the skin, nails, and sweat glands. It is caused by a mutation in the TP63 gene, which is responsible for the developme...

Ameloblastic carcinoma is a rare and aggressive type of cancer that affects the cells of the jawbone. It is a malignant tumor that is composed of both epithelial and mesenchymal cells. It is usually found in the mandible or maxilla and can spread ...

Ameloblastoma is a rare, benign tumor of the jawbone that usually affects the mandible (lower jaw). It is a slow-growing tumor that can cause facial disfigurement if left untreated. It is most common in adults between the ages of 30 and 50, and is...

Amelocerebrohypohidrotic syndrome is a rare genetic disorder that affects the development of the brain, skin, and sweat glands. It is caused by a mutation in the FOXI1 gene. Symptoms of this disorder include intellectual disability, seizures, hear...

Amelogenesis Imperfecta is a rare genetic disorder that affects the development of tooth enamel. It is caused by mutations in the genes responsible for the production of enamel proteins. Symptoms of the disorder include discolored, pitted, or chal...

Amelogenesis Imperfecta is a rare genetic disorder that affects the development of tooth enamel. People with this condition have abnormal enamel formation, which can result in teeth that are discolored, pitted, or prone to rapid wear and breakage....

Amenorrhea facts Amenorrhea refers to the absence of menstrual periods; it may be either primary (meaning a woman never developed menstrual periods) or secondary (absence of menstrual periods in a woman who was previously menstruati...

Aminopterin/methotrexate embryofetopathy is a rare birth defect caused by the use of the drugs aminopterin or methotrexate during pregnancy. These drugs are used to treat certain types of cancer, autoimmune diseases, and other conditions. When tak...

Amish lethal microcephaly is a rare genetic disorder that affects the Amish population. It is characterized by a small head size, severe intellectual disability, and early death. It is caused by a mutation in the ASPM gene, which is responsible fo...

Amish nemaline myopathy is a rare, inherited neuromuscular disorder that affects the muscles of the body. It is caused by mutations in the NEB gene, which is responsible for producing a protein called nebulin. Symptoms of the disorder include musc...