[A new mutation in COL1A1 gene in a family with osteogenesis imperfecta]

Osteogenesis imperfecta (OI) is a congenital disease of connective tissue of increased bone fragility and low bone mass, most often caused by single amino acid substitution of glycine residues in the collagen, type I, alpha 1 protein (COL1A1) gene or the collagen, type I, alpha 2 protein (COL1A2) gene, encoding type I procollagen chains. We describe here the clinical, biochemical, and molecular characterization of a family with type I OI in China and would like to explore whether the biochemical characterization of OI in China is different from that in other countries.

Through clinical research, we study the clinical characteristic of the OI household. Genomic DNA was isolated from peripheral blood lymphocytes of the proband and his family members by saturation hydroxybenzene-chloroform methods; amplification of target COL1A1 gene by Polymerase chain reaction with 23 pairs of different primers; purification; direct sequencing of the Polymerase chain reaction product. According to the mutation site, we took restriction enzyme analysis to 50 normal control people.

We found a G and A heterozygosis mutation at the exon 48 causing an a1 (I) p. G1157D substitution in the proband and his sister who is also a sufferer of OI. At the same time, other normal people in the family and other normal control people do not have this change.

This is the first delineation of an aspartic acid substitution in new site of the a1 (I) chain causing nonlethal osteogenesis imperfecta. Only nine aspartic acid substitution in type I collagen has been fully reported in the world. Now we revealed a new nosogenesis of OI. Since only few of nucleotide changes in type I collagen glycine codons would result in an aspartic acid substitution, these are predicted to be infrequent. Furthermore, it is possible to suggest that nosogenesis of OI in china is different from other countries.