Fabry disease is a rare genetic disorder of fat (lipid) metabolism characterized by a deficiency of the enzyme alpha-galactosidase A (previously known as ceramide trihexosidase). The disorder belongs to a group of diseases known as lysosomal storage disorders. Lysosomes function as the primary digestive units within cells. Enzymes within lysosomes break down or digest particular compounds and intracellular structures. Alpha-galactosidase functions to remove the terminal galactose moieties from complex sugary-fat molecules termed glycosphingolipids. Absence or less than 1% of the alpha-galactosidase A enzyme results in the classic subtype of Fabry disease due to the abnormal accumulation of a specific sugary-fat material (termed globotriaosylceramide, GL-3 or Gb3) in various organs of the body, particularly in the blood vessels. Symptoms of classic Fabry disease typically include onset in childhood or adolescence, the appearance of clusters of rash-like discolorations on the skin (angiokeratomas), excruciating pain in the hands and feet, and abdominal pain, absent or markedly decreased sweating (anhidrosis or hypohidrosis), and specific changes in the cornea of the eye (corneal dystrophy) that do not affect vision. Later in the course of the disease, kidney failure, heart disease, and/or strokes cause life-threatening complications.
Individuals with alpha-galactosidase A levels greater than 1% of normal have a somewhat milder or attenuated, later-onset subtype of the disease, and typically do not have the early-onset symptoms including the skin lesions, eye changes, decreased sweating, and pain in the extremities. They develop kidney, heart, or cerebrovascular (i.e., stroke) disease in adult life.
Fabry disease, which is inherited as an X-linked trait, affects males and females. Males are more uniformly affected whereas females have variable affects and may be asymptomatic or as severely affected as males.