P3H1 and osteogenesis imperfecta: So far, numerous mutations in genes encoding collagen type I (Col I) or involved in collagen modification, e.g., cartilage-associated protein (CRTAP) and leucine proline-enriched proteoglycan 1 (LEPRE1) [4,5]; folding, e.g., serpin peptidase inhibitor (SERPINH1) [6]; and processing, e.g., bone morphogenetic protein 1 (BMP1) [7], have been shown to cause various types of OI.