Mutations of either DSP or DPP domain in humans caused dentinogenesis imperfecta (DGI) type II (DGI-II, OMIM #125490) and type III (DGI-III, OMIM 125500) and dentin dysplasia (DD) type II (DD-II, OMIM 125420)19–21, the most common dentin genetic diseases. The gene discussed is DSP; the disease is dentin dysplasia.