Fabry's disease is an X-linked inborn error of glycosphingolipid catabolism caused by deficient activity of α-galactosidase A, a lysosomal exoglycosidase.¹,² In males with the classic form of the disease, there is little if any α-galactosidase A activity. As a result, undegraded glycosphingolipids accumulate, particularly in the vascular endothelium. These deposits cause the characteristic angiokeratomas, acroparesthesias, hypohidrosis, and corneal opacities of Fabry's disease. Death in early adulthood in affected persons may be due to vascular disease of the heart, kidney, or brain. These abnormalities are absent in males with the cardiac variant of the disease. Those with the cardiac variant . . .