Tandem MS assays of Gaucher, Niemann–Pick-A/B, Krabbe, Pompe and Fabry diseases (left panel). GD, GC, GHA and GHI are Gaucher disease, carrier, healthy adult, and healthy infant patients, respectively. NPD, NPC, NPHA and NPHI are for Niemann–Pick-A/B samples. KD, KHA and KHI are for Krabbe samples. PD, PC, PHA and PHI are for Pompe samples. FD, FC, FHA and FHI are for Fabry samples. The right panel shows Hurler disease assay results