What is Fabry Disease?
Fabry disease is a lysosomal storage disorder caused by a deficiency of the alpha-galactosidase A enzyme. As this is an X-linked recessive disorder, generally males are affected with a classic form of the disease, but carrier females can exhibit milder symptoms with later age of onset than males. There is also an atypical form of this condition.
The classic form 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, hypohidrosis, but there are reports of increased sweating, hyperhidrosis), and characteristic eye changes such as cloudiness of the cornea and/or lens (vision is typically not affected). Less common symptoms include hearing loss and ringing in ears (tinnitus), gastrointestinal issues, obstructive pulmonary disease such as chronic bronchitis or wheezing, and swelling (edema) in the lower extremities in adulthood.
The symptoms that are a major cause of mortality are renal insufficiency, cardiac complications, and cerebrovascular disease. The kidney function slowly deteriorates over time with end-stage renal disease (ESRD) usually occurring in one's 30s-50s. Hypertension is the most frequent cardiac manifestation, this and other cardiac issues may lead to angina (chest pain), arrhythmia, heart attack, and heart failure. Cerebrovascular disease often presents as stroke or transient ischemic attacks (TIA).
In the atypical forms, most of the classic symptoms do not manifest. Typically there is only involvement of the heart or kidneys later in life. This difference in presentation is attributed to higher activity levels of the alpha-galactosidase A as compared to those individuals with the classic form.
Carrier females may be asymptomatic or may exhibit symptoms ranging from mild to severe. However, in most cases, symptoms tend to be milder with onset being later in life than in their affected male relatives.
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 diphenylhydantoin, carbamazepine, or gabapentin. Renal insufficiency can initially be treated with ACE inhibitors or angiotension receptor blockers to reduce protein in the urine. Late stage renal involvement may necessitate 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 renal, cardiac, or cerebrovascular disease, other medications may be recommended to help manage kidney/heart disease and stroke.
What is the prognosis for a person with Fabry Disease?
The majority of affected males with Fabry disease live well into adulthood, with an average life expectancy of ~58 years. Renal 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 may be more severely affected.