Niemann-Pick disease type C (NPC) is an inherited lipid storage disorder in which excessive amounts of harmful lipids accumulate in the spleen, liver, lungs, bone marrow, and brain. This will result in many complications including hepatosplenomegaly, ascites, seizures, neurological problems, and/or respiratory failure. The disease can start at ages that range between the prenatal period and 50 years. The earlier the disease onset is, the more severe the symptoms are. About 20% of cases have the severe infantile form with neurological involvement before age two and delayed motor milestones as well as hypotonia. The classic form of the disease occurs mostly in childhood with the insidious onset of ataxia, vertical supranuclear gaze palsy (VSGP), and dementia. Affected adults are more likely to have dementia or psychiatric problems.
Globally, the estimated incidence of NPC is calculated at 1/140,000 births. NPC is divided into two forms according to the causative gene (NPC1 and NPC2). Diagnosis of NPC is mainly based on demonstrating these anomalies in cultured fibroblasts (especially through the cytochemical "filipine test"). Prenatal diagnosis is also available via molecular or cellular biology. Cholesterol lowering agents can be used as supporting factors, but they have no effect on the neurological signs of the disease. Generally, there is no available treatment for NPC to date.