p.R301X Mutation and Variable Phenotypic Appearance of Fabry Disease

Mosaic Fabry Disease in a Male Presenting as Hypertrophic Cardiomyopathy

We describe a 55 year old male diagnosed with cardiomyopathy due to Fabry disease. Biochemical testing of blood spot and plasma showed low-normal alpha-galactosidase A (α-Gal A) levels. Genetic testing revealed somatic mosaicism for GLA c.901C>T, p.(Arg301Ter). Usually, males with Fabry disease due to loss of function variants in GLA show symptoms of the multisystemic features of the condition early in life, and have very low levels of the α-Gal A enzyme. This demonstrates that the diagnosis of Fabry disease in males with cardiomyopathy should still be considered even in the context of a normal plasma enzyme assay.