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目的了解散发性大肠癌微卫星不稳定及其hMSH2基因突变情况。方法用6个微卫星位点标记，PCR法检测微卫星不稳定性（microsatelliteinstabilty，MI），银集PCR－SSCP法检测hMSH2基因5、7、8、12、13、15外显子突变。结果60例大肠癌中，微卫星改变总的发生率为50％（30／60）；20例（3333％）表现微卫星不稳定性，其中4例同时有杂合性缺失（lossofheterozygosityLOH），DNA复制错误（RER）阳性11例（1833％）；14例（233％）检测到LOH。8例微卫星不稳定性大肠癌组织检测到第5外显子杂合性突变，而未发现胚系突变。结论散发性大肠癌中微卫星不稳定是一个常见的分子事件，与hMSH2基因胚系突变无关，可能为体细胞性突变或／和缺失所致。
Objective To understand the microsatellite instability and hMSH2 gene mutation in sporadic colorectal cancer. Methods Six microsatellite markers were used to detect the microsatellite instability (MI) by PCR and silver-set PCR-SSCP was used to detect mutations in exons 5, 7, 8, 12, 13, and 15 of hMSH2 gene. Results In 60 cases of colorectal cancer, the total incidence of microsatellite changes was 50% (30/60); 20 cases (3333%) showed microsatellite instability, and 4 cases had loss of heterozygosity (LOS) and DNA. 11 cases (1833%) were positive for replication error (RER); LOH was detected in 14 cases (233%). Eight heterozygous mutations in exon 5 were detected in 8 microsatellite unstable colorectal cancer tissues, but no germline mutation was found. Conclusion Microsatellite instability in sporadic colorectal cancer is a common molecular event. It is not related to germline mutation of hMSH2 gene and may be due to somatic mutation or/and deletion.