NEW MUTATIONS IN EXT1 AND EXT2 IN CHINESE FAMILIES WITH HEREDITARY MULTIPLE EXOSTOSES

Hereditary multiple exostoses (HME) is a dominant disorder characterized by the presence of multiple exostoses at the end of long bones. Mutations in the EXT1 and EXT2 genes are major causes of HME. In this study, we clinically characterized nine unrelated families with multiple exostoses. Sanger sequencing was used to analyze the mutation of the EXT1 and EXT2 genes. Three new muta tions (c.794-802delTATTCAAGG and c.1049_1051delCTTinsAATCTGATTCC in EXT1, c.799G>T in ext2) were identified in these families. Two of the new mutations were predicted to produce truncated protein due to frameshift and nonsense mutations. These findings expand the mutation spectrum of EXT1 and EXT2 and may help us to understand the molecular basis of HME in order to facilitate genetic counseling.