The dysfunction or absence of CypB has been implicated in various pathological conditions, including Hereditary Equine Regional Dermal Asthenia (HERDA), a genetic skin disorder in horses characterized by hyperextensible skin and pronounced scarring (Tryon et al., 2005), and osteogenesis imperfecta (OI) in mice, a condition that arises when the Prolyl 3-Hydroxylase 1/Cartilage-associated Protein/Cyclophilin B (P3H1/CRTAP/CypB) complex is compromised (Choi et al., 2009). The gene discussed is CRTAP; the disease is osteogenesis imperfecta.