A novel COL1A1 nonsense mutation causing osteogenesis imperfecta in a Chinese family

PURPOSE: To identify the genetic defect of osteogenesis imperfecta (OI) type I in a large Chinese family of five generations. METHODS: Seventeen members in an OI type I family were recruited, and clinical examinations were performed. All members were genotyped with microsatellite markers at loci associated with OI. A two-point LOD score was calculated using the Linkage package. A mutation was detected by direct sequencing. RESULTS: All affected individuals in the family had fractured a bone more than once, and their sclerae were blue. Significant evidence of linkage was obtained at markers D17S1180 (LOD score [Z]=2.91, at recombination fraction [theta]=0.0) and D17S1319 (Z=2.20, at theta=0.0), respectively. Sequencing of the COL1A1 gene revealed a C > T transition in exon 36, which caused a substitution of Gln at codon 644 to a stop codon (Q644X). This mutation was not observed in unaffected or 100 normal unrelated individuals. CONCLUSIONS: This study is the first report that OI is associated with the mutation Q644X of COL1A1.