Contributor: Gordon K. Klintworth
Niemann-Pick disease type C  (juvenile type of  Niemann-Pick disease, Niemann Pick disease with cholesterol esterification block, subacute Niemann-Pick disease, juvenile form of Niemann-Pick disease, chronic neuropathic form of Niemann-Pick disease, OMIM #257220) is one variety of Niemann-Pick disease. It was formerly referred to as Niemann-Pick disease type C in the Crocker classification. According to the current classification of Niemann-Pick disease patients with this variant would be considered to have Niemann-Pick disease type II. This lysosomal storage disease is a rare inherited sphingomyelin storage disease with a defect in cholesterol esterification due to a mutation in the NPC1 gene. The condition begins in childhhood (~5 years of age).  Affected persons have a severe sphingomyelinase deficiency and develop visceral abnormalities early in life, but there is marked phenotypic heterogeneity in nervous system involvement.  Some patients may survive >15 years.