SMPD1 and lysosomal storage disease: Acid Sphingomyelinase Deficiency (ASMD) type B is a non-neuronopathic lysosomal storage disorder caused by deficient acid sphingomyelinase activity due to biallelic pathogenic variants in the SMPD1 (Sphingomyelin Phosphodiesterase 1) gene [1, 2].