On the basis of sequence analysis of a relatively small pool of individuals with perinatal lethal OI, estimate of the causative gene proportions are similar: 95% of infants are heterozygous for a mutation in COL1A1 or COL1A2 and the remainder had recessively inherited forms with mutations in other genes (Bodian et al. 2009). The gene discussed is COL1A1; the disease is osteogenesis imperfecta.