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Fabrys Diseaseis caused by the lack of or faulty enzyme needed to metabolize lipids, fat-like substances that include oils, waxes, and fatty acids. The enzyme is known as ceramide trihexosidase, also called alpha-galactosidase-A. A mutation in the gene that controls this enzyme causes insufficient breakdown of lipids, which build up to harmful levels in the eyes, kidneys, autonomic nervous system, and cardiovascular system. Since the gene that is altered is carried on a mother’s X chromosome, her sons have a 50 percent chance of inheriting the disorder and her daughters have a 50 percent chance of being a carrier. Some women who carry the genetic mutation may have symptoms of the disease. Symptoms usually begin during childhood or adolescence and include burning sensations in the hands that gets worse with exercise and hot weather and small, raised reddish-purple blemishes on the skin. Some boys will also have eye manifestations, especially cloudiness of the cornea. Lipid storage may lead to impaired arterial circulation and increased risk of heart attack or stroke. The heart may also become enlarged and the kidneys may become progressively involved. Other symptoms include decreased sweating, fever, and gastrointestinal difficulties, particularly after eating.
Symptoms: Symptoms of Fabrys disease depend on the level of enzyme deficiency. Males are usually the most severely affected and, in patients with complete enzyme deficiency, symptoms develop in childhood or adolescence. Pain and abnormal feelings occur in the extremities. Red, raised lesions known as angiokeratomas occur on the skin and within the mouth. The ability to sweat is decreased. The cornea and lens of the eye become clouded. Later, kidney failure occurs which secondarily causes hypertension. Heart function can also be impaired.
Patients with partial enzyme activity may not show any symptoms or they may begin late in life. The impaired heart function is typically the primary problem.
Causes:
This condition is inherited in an X-linked pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes in each cell. In males, 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.
Unlike other X-linked disorders, Fabrys disease causes significant medical problems in many females who have one altered copy of the GLA gene. These women may experience many of the classic features of the disorder, including nervous system abnormalities, kidney problems, chronic pain, and fatigue. They also have an increased risk of developing high blood pressure, heart disease, stroke, and kidney failure. The signs and symptoms usually begin later in life and are milder in females than in their affected male relatives.
Treatment:
Enzyme replacement may be effective in slowing the progression of the disease. The pain in the hands and feet usually responds to anticonvulsants such as phenytoin and carbamazepine. Gastrointestinal hyperactivity may be treated with metoclopramide. Some individuals may require dialysis or kidney transplantation.
