Liquid Chromatography–Tandem Mass Spectrometry Quantification of Globotriaosylceramide in Plasma for Long-Term Monitoring of Fabry Patients Treated with

Fabry disease is a rare X-linked lysosomal storage disor-der resulting from a deficiency in the -galactosidase A enzyme. Deficiency in the activity of this enzyme causes an accumulation of neutral glycosphingolipids, predomi-nantly globotriaosylceramide (GL-3), in most nonneural tissues and in body fluids (1). Recent clinical studies indicate that tissue and plasma GL-3 concentrations in Fabry patients can be significantly reduced by enzyme replacement therapy (2–5). GL-3 (see Fig. 1 in the Data Supplement that accompa-nies the online version of this Technical Brief a