TGFB1 and osteogenesis imperfecta: Assuming the limitations of the present study, our hypothesis linking OI disease severity with the activation of TGF-β pathway is in line with the increased skeleton TGF-β activation that mice models resembling severe OI, Col1a2+/G61°C, Crtap−/-, and Col1a1Jrt/+ exhibit (Grafe et al., 2014; Tauer et al., 2018).