CRTAP and osteogenesis imperfecta: Further, TGF-β seems to play a role in OI pathology as mouse models of recessive (mutation in the Crtap gene; Crtap−/−) and dominant (collagen type I mutations; Col1a2tm1.1Mcbr & Col1a1Jrt/+) OI showed excessive TGFβ-signaling in the skeleton39,40.