SMPD1 and nervous system disorder: Among them is the infantile neurovisceral form of the acid sphingomyelinase deficiency (ASMD), also called Niemann Pick type A. Loss of function mutations in the sphingomyelin phosphodiesterase 1 (SMPD1) gene encoding acid spingomyelinase (ASM) cause severe neurological disease, neurodegeneration and death in the first years of life [17].