Plasma glucosylsphingosine levels in relation to GBA genotype. Glycolipid concentration was determined in plasma samples collected before initiation of therapy. Controls (n = 28), N370S heterozygotes (n = 22), L444P heterozygotes (n = 12), N370S homozygotes (n = 19), and N370S/L444P compound heterozygotes (n = 18).