【Objective】To investigate the polymorphisms of the EXT1 and EXT2 genes in Southern Han Chinese people and in 13 hereditary multiple exostoses(HME) patients whose causal mutations had already been identified.【Methods】Genomic DNA was extracted from 50 healthy unrelated southern Chinese Han individuals and 13 HME patients with known casual mutations in these two genes. PCR products spanning the coding regions

intron-exon boundaries

5’and 3’UTR of the genes were sequenced. Variations identified in the sequences were compared with those retrieved from the databases. 【Results】 Fifteen genetic variations of EXT1 were identified

of which 3 are synonymous coding variations

11 in intronic region and 1 in 3’UTR. 3 of the 15 variations were novel SNPs. Twenty-two variations of EXT2 were detected

3 are synonymous coding variations

16 in intronic region and 3 in 3’UTR. 7 of the 22 genetic variations in EXT2 were novel. 【Conclusions】 Ten novel variations in EXT1 and EXT2 gene have been identified in our study. Twenty-seven variations already in the databases were confirmed. Our results provide useful information for the genetic variations of the two genes among Southern Han Chinese. The results also provide important information for differentiation of causal mutations of EXT1 and EXT2 genes from innocuous polymorphisms.