Observational cohort study of the natural history of Niemann-Pick disease type C in the UK: a 5-year update from the UK clinical database.

Background Niemann-Pick disease type C (NP-C) is a rare neurovisceral lipid storage disorder characterised by progressive, disabling neurological symptoms and premature death in most patients. During the last decade, national cohort studies have accrued a great deal of data on the symptomatology and natural history of NP-C.