COL5A1 expression in osteoblasts and vascular smooth muscle cells is induced by TGF-β1 [59,60] and haplo-insufficiency leads to the heritable connective-tissue disorder Ehlers-Danlos syndrome that is characterized by an altered collagen-fibrillar structure of the dermis, joints, eyes and blood vessels [61]. Here, COL5A1 is linked to Ehlers-Danlos syndrome.