P3H1 and osteogenesis imperfecta: Cartilage-associated protein (CRTAP), which forms a trimeric complex with P3H1 and cyclophilin B for 3-hydroxylation of proline 986 residue of collagen α1(I) and proline 707 residue of collagen α2(I) (Morello et al., 2006; Mehawej et al., 2014), respectively, was found to cause an autosomal recessive form of OI (Morello et al., 2006; Girisha et al., 2019).