Fabry disease in patients with hypertrophic cardiomyopathy (HCM).

Fabry disease is an X-linked recessive lysosomal storage disorder with variable phenotype characterized by the accumulation of glycosphingolipid in various tissues. Unlike patients with the classical systemic Fabry disease entity, who present with multiple organ involvement, patients with a cardiac variant of Fabry disease are characterized mainly by myocardial hypertrophy. Therefore, the cardiac variant of Fabry disease may be defined as a cardiomyocytic storage disorder, thus, mimicking the clinical features of hypertrophic obstructive and especially non-obstructive cardiomyopathy. In patients with unexplained left ventricular hypertrophy the diagnosis of a cardiac variant of Fabry disease is performed by light- and electron microscopic evaluation of endomyocardial catheter biopsy specimens and/or serologic investigations (decreased activity of alpha-galactosidase A in plasma or leucocytes). Several studies show that between 4% and 8% of unselected patients with the clinical features of hypertrophic non-obstructive cardiomyopathy have a cardiac variant of Fabry disease. In each patient with unexplained myocardial hypertrophy concealed myocardial storage disease, especially cardiac Fabry disease has to be considered and should be ruled out or confirmed by endomyocardial catheter biopsy. This is important because of the recently reported alpha-galactosidase A enzyme replacement therapy in Fabry disease. Randomized, multicenter studies are mandatory to test the hypothesis that enzyme replacement therapy leads to a beneficial clinical effect in the cardiac variant form of Fabry disease and may prevent the progression of the disease in asymptomatic patients.