CRTAP and osteogenesis imperfecta: It has been reported that COL1A1 and COL1A2 mutations account for around 90% of all cases of OI in an autosomal dominant manner (Van Dijk and Sillence, 2014), while the remaining mutations of the CRTAP (Type VII, OMIM #610682) and P3H1 (Type VIII, OMIM #610915) genes are responsible for rare and severe to intermediate OI in an autosomal recessive manner (Byers and Pyott, 2012).