Quantification of glucosylsphingosine in plasma of type 1 Gaucher type patients. (A) Fragmentation spectrum of glucosylsphingosine. Predominant product ions (m/z 282.2 and 264.2) generated by collision induced fragmentation of glucosylsphingosine (m/z 464.2) are indicated. (B) Diagnostic value of glucosylsphingosine in type 1 Gaucher disease. Glucosylsphingosine and glucosylceramide levels in plasma of type 1 Gaucher patients (n = 64 and n = 49, respectively) and controls (n = 28). Patients homozygous for the mutation N370S are indicated with open circles (n = 19). Lines represent the median value in each group.