 Anderson - Fabry disease AFD is a rare, X - linked hereditary systemic lysosomal storage disorder which usually affects the heart. The reported incidence of AFD is between 1 in 117000 and 1 in 240000 live births. Due to a deficiency of the enzyme α - galactosidase, glycosphingo-lipids, primarily globotriaosylceramide, are stored also in endothelial and myocardial cells, leading to morphologic and functional changes. AFD-cardiomyopathy progresses with age and with the course of the disease, leading to reduced life expectancy. The investigators hypothesize, that AFD could be underdiagnosed in patients with only mild or moderate left ventricular myocardial hypertrophy. Early diagnosis of AFD may be relevant since affected patients might benefit from enzyme replacement therapy at early stage of disease. The investigators will examine 4000 consecutive patients with an echocardiographically measured interventricular septum thickness of 12mm. Urine samples will be collected and Gb3-isoforms, creatinine and α - Galactosidase activity will be measured. 