Niemann-Pick type B disease in adulthood

Niemann-Pick disease type B (NP-B) or acid sphingomyelinase deficiency (DSMA) is an autosomal recessive lysosomal storage disease caused by a mutation in the sphingomyelin phosphodiesterase 1 (SMPD1) gene. SMPD is responsible for an accumulation of sphingomyelin in lysosomes as well as abnormalities in the lipid constituents of cell membranes. Clinically three entities secondary to DSMA can be distinguished: Niemann-Pick type A (NP-A) an early neurovisceral form; Niemann-Pick type B a chronic visceral form; and Niemann-Pick type A/B (NP-A/B) a chronic neurovisceral form. NP-A disease is characterized by severe visceral and neurodegenerative damage which is progressive and fatal within the first three years of life. In B forms there is no neurological involvement and the age of onset is highly variable with adult onset possible. The clinical picture often associates almost constant hepatosplenomegaly interstitial lung disease that is generally asymptomatic or manifested by