Additionally, c.769G > A (p.G257R) of COL1A1 and c.1009G > A (p.G337S) of COL1A2, which were the most common variants of COL1A1 and COL1A2, were identified in 10 and 6 unrelated families, respectively, suggesting that these two mutations are hotspot mutations in the Chinese OI cohort. The gene discussed is COL1A2; the disease is osteogenesis imperfecta.