Niemann–Pick disease

Niemann–Pick disease (NP), also known as acid sphingomyelinase deficiency (ASMD), is a group of rare genetic diseases of varying severity. These are inherited metabolic disorders in which sphingomyelin accumulates in lysosomes in cells of many organs. NP types A, A/B, and B are caused by mutations in the SMPD1 gene, which causes a deficiency of an acid sphingomyelinase (ASM). NP type C is now considered a separate disease, as SMPD1 is not involved, and there is no deficiency in ASM.

Underlined words are explained — tap any of them.