Osteogenesis imperfecta (OI) most commonly results from heterozygous dominant COL1A1 or COL1A2 variants (~85% of classic cases), with additional dominant or recessive defects in collagen-processing genes producing a spectrum from mild (Type I) to perinatal lethal (Type II) disease [171]. This evidence concerns the gene COL1A2 and osteogenesis imperfecta.