The IDS enzyme activity of this mouse model was impaired in DBSs, whereas other enzyme activity of lysosomal storage disorder (LSD), such as α-galactosidase A (GLA), α-glucosidase (GAA), α-iduronidase (IDUA), acid β-glucosidase (ABG), acid sphingomyelinase (ASM), and galactosylceramidase (GALC), either remained within normal range or elevated significantly by LC–MS/MS-based enzyme assay (Fig. 1E, Supplementary Table S1). Here, SMPD1 is linked to lysosomal storage disease.