α-Galactosidase A Genotype N215S Induces a Specific Cardiac Variant of Fabry Disease

Abstract

Background— Hypertrophic cardiomyopathy is the most common type of cardiomyopathy, but many patients lack sarcomeric/myofilament mutations. We studied whether cardio-specific α-galactosidase A gene variants are misinterpreted as hypertrophic cardiomyopathy because of the lack of extracardiac organ involvement. Methods and Results— All subjects who tested positive for the N215S genotype (n=26, 13 females, mean age 49±17 [range, 14–74] years) were characterized in this prospective monocentric longitudinal cohort study to determine genotype-specific clinical characteristics of the N215S (c.644A>G [p.Asn215Ser]) α-galactosidase A gene variant. All subjects were initially referred with suspicion of genetically determined hypertrophic cardiomyopathy. Cardiac hypertrophy (interventricular septum, 12±4 [7–23] mm; left ventricular posterior wall, 11±4 [7–21] mm; left ventricular mass, 86±41 [46–195] g/m 2 ) was progressive, systolic function mainly preserved (cardiac index 2.8±0.6 [1.9–3.9] L/min per m 2 ), and diastolic function mildly abnormal. Cardiac magnetic resonance imaging revealed replacement fibrosis in loco typico (18/26, 69%), particularly in subjects >50 years. Elderly subjects had advanced heart failure, and 6 (23%) were suggested for implantable cardioverter-defibrillator therapy. Leukocyte α-galactosidase A enzyme activity was mildly reduced in 19 subjects and lyso-globotriaosylceramide slightly elevated (median, 4.9; interquartile range, 1.3–9.1 ng/mL). Neurological and renal impairments (serum creatinine, 0.87±0.20; median, 0.80; interquartile range, 0.70–1.01 mg/dL; glomerular filtration rate, 102±23; median, 106; interquartile range, 84–113 mL/min) were discreet. Only 2 subjects developed clinically relevant proteinuria. Conclusions— α-Galactosidase A genotype N215S does not lead to the development of a classical Fabry phenotype but induces a specific cardiac variant of Fabry disease mimicking nonobstructive hypertrophic cardiomyopathy. The lack of prominent noncardiac impairment leads to a significant delay in diagnosis and Fabry-specific therapy.