Abstract: BACKGROUND ＆ AIM: To investigate the mutation and methylation status of mismatch repair gene human mutl homolog l gene(hMLH1) in sporadic colorectal cancer. MATERIAL AND METHODS: Genomic DNA extracted from 50 sporadic colorectal cancer tissues was subjected to the mutation analysis of exon3,8,12,13,15,16 in hMLH1 gene by capillary electrophoresis-single strand conformation polymorphism(CE-SSCP) followed by DNA sequencing technology,and methylation of hMLH1 promotor was measured by HapⅡ,MspⅠenzyme and reverse transcriptase-polymerase chain reaction(RT-PCR) technology. RESULTS: ① Among the 50 cases,3 cases showed the missense mutation in exon 12(GTT→GAT，Val384Asp),and the mutation rate was 6 ％.② 9 cases showed methylation of hMLH1 promotor,and methylation rate was 18 ％. CONCLUSION: Mutation of hMLH1 gene in sporadic colorectal cancer may be casual events;people with the missense mutation in exon 12 of hMLH1 gene may be subject to sporadic colorectal cancer;there is no significant correlationship between hMLH1 gene methylation and clinicopathology in sporadic colorectal cancer.

Key words: hMLH1 gene, mutation, methylation, colorectal cancer