What causes Niemann-Pick type C disease?

Niemann-Pick type C disease (NP-C) is caused by an inherited change (or mutation) in one of two genes; NPC1 or NPC2.1,2 These two genes produce a protein which plays an important role in the movement and recycling of fatty molecules within the cells. When the NPC1 or NPC2 gene is changed, the protein does not function properly and causes the fatty molecules to become trapped within the cell.2 NP-C is commonly known as a lysosomal storage disorder. This is because the NP-C protein is located in the cell membrane of a small compartment, known as a lysosome.

The build-up of fatty molecules in the brain damages the nerve cells (neurons), causing them to change shape, grow abnormally and can also cause the cells to die. These changes in shape, growth and the loss of nerve cells are responsible for the neurological symptoms of NP-C, for example problems with eye movement, balance or speech.3,4 The accumulation of fatty molecules can also lead to the abnormal enlargement of the liver and/or spleen, a symptom most often seen in infants and children with NP-C.4


  1. Patterson MC, Hendriksz CJ, Walterfang M, et al, on behalf of the NP-C Guidelines Working Group. Recommendations for the diagnosis and management of Niemann–Pick disease type C: An update. Mol Genet Metab 2012. 106(3):330–344.
  2. Vanier MT. Niemann-Pick disease Type C. Orphanet Journal of rare Diseases. 2010;5:16.
  3. Walkley SU, Suzuki K. Consequences of NPC1 and NPC2 loss of function in mammalian neurons. Biochim Biophys Acta 2004;1685:48–62.
  4. Wraith E, Baumgartner M, Bembi B et al. Recommendations on the diagnosis and management of Niemann-Pick disease type C. Mol Genet Metab 2009;98:152–165.