Niemann-Pick type C disease (NP-C) is a rare genetic neurological disorder caused by accumulation of lipids (fatty molecules such as cholesterol and gangliosides), due to a defect in the function of two proteins (called NPC-1 and NPC-2 proteins) which regulate the movement of lipids inside the cells of the body, especially the central nervous system. Accumulation of these substances causes structural damage and functional impairment of these cells. This inherited fatal disease manifests progressively with severe, neurological very disabling signs and symptoms. Information available on the natural history of the disease confirms that NP-C is an invariably progressive neurological disease. It mostly affects infants and children, but can also manifest in adults.
The symptoms of NP-C are highly variable and become most apparent in mid-to-late childhood. The varied symptoms of NP-C include eye movement problems, difficulty in swallowing, slurred and irregular speech, gait and postural abnormalities, sleep problems, seizures, behavioral abnormalities, and progressive intellectual decline which often leads to severe dementia. Some young children show also an enlarged spleen and/or liver.