Niemann-Pick disease type C (NP-C) is a rare genetic neurological disorder caused by accumulation of lipids (fatty substances), due to a defect in the function of two proteins (called NPC-1 and NPC-2) which regulate the movement of lipids inside the cells of the body, especially the central nervous system.

Accumulation of these substances causes structural damage to these cells. This inherited disease is progressive with severe neurological signs and symptoms. NPC mostly affects infants and children, but can also be first diagnosed in adults.

The symptoms of NP-C are highly variable and become most apparent in mid-to-late childhood. Diagnosing NP-C is not straightforward, and because of the highly varied nature of its signs and symptoms this disease is often confused with other neurological diseases, or goes undetected.

Consequently, the true number of cases of NP-C may be higher than currently thought. The diagnostic tests required to confirm NP-C, are complicated, and can only be carried out at a very limited number of highly specialised laboratories.

There is currently no cure for NP-C, and until recently, treatments focused only on managing symptoms. These therapies may be at least partially successful in treating some symptoms of NP-C, but have no impact on disease progression or long-term outcomes.