Identification of mutations in EXT1 and EXT2 genes in six Chinese families with multiple osteochondromas

摘要

The aim of the present study was to identify mutations of major causative genes in six unrelated Chinese families with multiple osteochondromas (MO). Radiographic examinations and genetic analyses were performed in 8 patients exhibiting typical features of MO. Analysis was also performed on unaffected members of the six families and 250 healthy volunteers. Radiographies of the patients revealed multiple exostoses in the cartilage of long bones. A total of five different mutations were identified, one in exostosin-1 (EXT1) and four in exostosin-2 (EXT2). Two novel mutations were detected in EXT2: A missense mutation, c.1385GA, in exon 8, resulting in p.Trp462X; and a splice site mutation, c.725+1GC, which consisted of a heterozygous guanine-to-cytosine transition at nucleotide 725+1 in intron 3. Three common EXT mutations were also detected: c.1036CT in exon 5 of EXT2 resulting in p.Gln346X; c.1299CA in exon 8 of EXT2 resulting in p.Phe433Leu; and c.1038AT in exon 2 of EXT1 resulting in p.Arg346Ser. In conclusion, the present study identified a novel missense mutation (c.1385GA) in exon 8 and a splicing mutation (c.725+1GC) in intron 3 of the EXT2 gene, which are responsible for MO in certain Chinese patients. The findings are useful for expanding the database of known EXT2 mutations and understanding the genetic basis of MO in Chinese patients, which may improve genetic counseling and the prenatal diagnosis of MO.