Niemann-Pick Disease, Type C - Genetics and Classification

Genetics and Classification

Approximately 95% of Niemann–Pick type C cases are caused by genetic mutations in the NPC1 gene, referred to as type C1; 5% are caused by mutations in the NPC2 gene, referred to as type C2. The clinical manifestations of types Niemann–Pick types C1 and C2 are similar because the respective genes are both involved in egress of lipids, particularly cholesterol, from late endosomes or lysosomes. The NPC1 gene is located on chromosome 18 (18q11-q12) and was described by researchers at the National Institutes of Health in July 1997.

• The NPC1 gene encodes a protein that is located in membranes inside the cell and is involved in the movement of cholesterol and lipids within cells. A deficiency of this protein leads to the abnormal build up of lipids and cholesterol within cell membranes.

• The NPC2 gene encodes a protein that binds and transports cholesterol. It has been shown to closely interact with NPC1.