Niemann-Pick type C is frequent in adult ataxia with cognitive decline and vertical gaze palsy

Niemann-Pick type C (NPC) disease is a rare, usually fatal neurodegenerative lysosomal storage disorder. It is inherited in an autosomal-recessive fashion and caused by mutation of either NPC1 (95%) or NPC2 gene.1 Age at onset is broadly variable, ranging from neonatal fatal neurovisceral manifestations to a primarily neurodegenerative disease in adulthood that may be recognized as late as 70 years of age.1 Due to its diverse clinical manifestation, correct diagnosis is challenging, frequencies might be underestimated, and diagnosis may be delayed, in particular in patients with adult-onset disease. This is particularly momentous because a potential therapy for deceleration of disease progression is now available.2