COL1A1 and Ehlers-Danlos syndrome, arthrochalasia type: The COL1A1 gene exhibits strong pleiotropy and contributes to the pathogenesis of a greater part of osteogenesis imperfecta (OI) and aEDS cases, and also a few cases of cEDS or vEDS (Malfait et al., 2020; Marini et al., 2017).