PPIB and connective tissue disorder: For instance, it has been described that CypB forms a complex with CRTAP (cartilage-associated protein) and prolyl 3-hydroxylase 1 and that mutations on any of these three proteins cause recessive form of esteogenesis imperfecta and loss or decrease of type I collagen prolyl 3-hydroxylation [33]–[35], which is a mechanism for connective tissue disease.