COL1A1 and Ehlers-Danlos syndrome: Apart from the role of pathogenic type I collagen variants for the development of osteogenesis imperfecta (OI) or brittle bone disease, specific variants in COL1A1 or COL1A2 have been identified as causes of different EDS types such as arthrochalasia EDS, cardiac-valvular EDS, as well as rare forms of vascular EDS and classic EDS and OI-EDS overlap syndromes (3, 23–27).