Mutations in COL1A1 and COL1A2 are associated with osteogenesis imperfecta (OI; OMIM# 166200, 166210, 259420, and 166220 for OI types I–IV), a connective tissue disorder featuring low bone mass and increased bone fragility (Foster, Ramnitz, et al., 2014). Here, COL1A1 is linked to osteogenesis imperfecta.