CRTAP and osteogenesis imperfecta: Our finding of a SERPINH1 p.L326P mutation in dogs with OI provides a valuable model for human medicine and identifies SERPINH1 as a fifth OI gene in addition to COL1A1, COL1A2, CRTAP, and LEPRE1. It has already been shown that a functional SNP in the promoter of the human SERPINH1 gene is associated in African American women with an increased risk for preterm premature rupture of membranes [22].