For example, different mutations in the COL1A1/COL1A2 genes (which code for pro-α1 (I) and pro-α2 (I) chains, resp.; both components are of type I collagen, the most abundant form of collagen in the body), can result in a phenotype of classical type EDS, arthrochalasia type EDS, mild to severe osteogenesis imperfecta (OI) or an overlapping phenotype of EDS/OI resulting in symptoms of EDS, joint hypermobility, skin hyperextensibility, atrophic scarring, and easy bruising in association with features of osteogenesis imperfecta, bone fragility, short stature, and blue sclerae. Here, COL1A2 is linked to osteogenesis imperfecta.