What is Fabry Disease?
Fabry disease is an inherited lysosomal storage disorder that is caused by harmful genetic changes, or mutations, in the GLA gene. The symptoms associated with Fabry disease are caused by a buildup of harmful substances in different organs and tissues of the body. Fabry disease is inherited in an X-linked manner, which means that the GLA gene is located on the X chromosome. Males typically have one copy of the X-chromosome and the GLA gene, while females generally have two copies. Because of this, Fabry disease primarily affects males, but carrier females can exhibit mild symptoms with a later age of onset than males. There is also both a classic and atypical form of this condition. The differences in presentation in this form are due to differences in the buildup of harmful substances in the body's tissues.
The classic form of Fabry disease occurs in males, with symptoms usually beginning in early childhood or adolescence. Patches of dark skin (angiokeratomas) are an early sign and most often appear on the lower half of the body. Other common symptoms include severe pain in the extremities (acroparesthesia); altered sweating (usually decreased sweating, aka hypohidrosis, but there are also reports of increased sweating, aka hyperhidrosis); and characteristic eye changes such as cloudiness in the cornea and/or lens (vision is typically not affected). Rarer symptoms include hearing loss and ringing in the ears (tinnitus); gastrointestinal issues; obstructive pulmonary disease such as chronic bronchitis or wheezing; and swelling (edema) in the lower extremities in adulthood.
Fabry disease symptoms that are a major cause of mortality are kidney disease, cardiac complications, and damage to the brain's blood vessels (cerebrovascular disease). Kidney function slowly deteriorates over time, with end-stage renal disease (ESRD) usually occurring between the ages of 30 and 50. High blood pressure is the most frequent cardiac manifestation, and this and other cardiac issues may lead to angina (chest pain), an abnormal heartbeat, heart attacks, and heart failure. Cerebrovascular disease often presents as strokes or brief episodes of blood loss to the brain (transient ischemic attacks).
In the atypical form of Fabry disease, most of the classic symptoms do not manifest. The atypical form usually only causes problems of the heart or kidneys, later in life.
Carrier females may be asymptomatic or may exhibit some of the symptoms of the classic disease. In most cases, symptoms are milder, with an onset later in life than for affected males. However, some female carriers have severe symptoms.
How common is Fabry Disease?
Fabry disease has an estimated pan-ethnic incidence of approximately 1 in 40,000 males, though regional incidences may vary. Because atypical forms may be unrecognized or diagnosed late in life, this incidence is likely an underestimate, and higher frequencies have been reported in both Taiwan and Italy.
How is Fabry Disease treated?
Pain may be treated with medications including diphenylhydantoin, carbamazepine, or gabapentin. Kidney disease can initially be treated with ACE inhibitors or angiotension receptor blockers to reduce protein in the urine. Late-stage renal involvement may require blood filtering (dialysis) or kidney transplantation.
There is evidence that enzyme-replacement therapy (ERT) may prevent some primary manifestations of Fabry disease, and it is typically recommended for all affected males (including children) and for some female carriers. However, because ERT may not improve symptoms of kidney, cardiac, or cerebrovascular disease, other medications may be recommended to help manage kidney disease, heart disease, and stroke.
What is the prognosis for an individual with Fabry Disease?
The majority of affected males with Fabry disease live well into adulthood, with an average life expectancy of approximately 58 years. Kidney disease and cardiac disease are the main causes of mortality. For carrier females, the prognosis is good and approaches a near-normal life span, though some individuals may be more severely affected.