Decline of plasma brain natriuretic peptide during enzyme replacement therapy in a female patient with heterozygous Fabry's disease.

There are no data regarding changes in plasma brain natriuretic peptide (BNP) levels in patients with Fabry's diseases during enzyme replacement therapy (ERT). We describe a patient with Fabry's disease who demonstrated the improvement in plasma brain BNP levels in response to ERT. Fabry's disease is an X-linked lysosomal storage disorder caused by a deficiency of the enzyme alpha-galactosidase A, which results in progressive intracellular accumulation of globotriaosylceramide (Gb3) in various organs including the heart. Cardiac involvement is frequent in Fabry's disease, resulting in cardiac dysfunction due to hypertrophic changes of the myocardium and thickening of the valves. Although ERT has been reported to improve cardiac function, no consensus has been reached regarding the effectiveness of ERT in female patients with heterozygous Fabry's disease. We report a 44-year-old woman having heterozygous Fabry's disease, who showed mitral valve thickening and regurgitation on echocardiogram. ERT was performed by intravenous infusion of recombinant alpha-galactosidase A every 2 weeks. We assessed the influences of ERT on cardiac function by measuring echocardiograhic parameters and monitoring BNP levels, which show treatment-induced drop in patients with heart failure. Although her cardiac function and mitral regurgitation assessed by echocardiography had not improved 18 months after the beginning of ERT, the plasma BNP level, which was 91.5 pg/ml before ERT, fell to 18.9 pg/ml. In conclusion, plasma BNP levels may be useful for evaluating the effectiveness of ERT for heterozygous Fabry's disease, even in patients who demonstrate no improvement in echocardiographic parameters of cardiac structure and function.