Neural stem cells are multi-potent and able to self renew to maintain its character throughout the life. Loss of self renewal ability of stem cells prevents recovery or replacement of cells damaged by disease with new cells. The Niemann-Pick type C1 (NPC1) disease is one of the neurodegenerative diseases, caused by a mutation of NPC1 gene which affects the function of NPC1 protein. We reported that NPC 1 gene deficiency could lead to lack of the self renewal ability of neural stem cells in Niemann pick type C disease. We also investigated many genes which are involved in stem cells proliferation and differentiation by gene profile in NPC mice. Diagnosis of NPC disease is difficult because it is accompanied by complicated symptoms and the fact that there is no effective treatment for NPC patients. Studies of these stem cells and their relationship to Niemann pick type C disease will provide new biomarkers for early diagnosis as well as a potential cure by use of targeted therapeutics for Niemann pick type C disease.