The majority of individuals with OI (85–90%) harbor dominant variants in the COL1A1 (HGNC:2197) and COL1A2 (HGNC:2198) genes, encoding the α1 and α2 chains of collagen type I, and are classified as having classic OI types I to IV (Marini et al., 2017). Here, COL1A2 is linked to osteogenesis imperfecta.