In 1994, Hollak et al. revealed chitotriosidase to be a novel biomarker for Gaucher disease but it soon was demonstrated that moderate elevation of chitotriosidase activity can be found in patients with some other lysosomal diseases and among them also in NPC (Hollak et al. 1994; Ries et al. 2006). This evidence concerns the gene CHIT1 and Gaucher disease.