目的:探讨小肠腺癌中微卫星不稳定(microsatellite instability,MSI)的情况,及其与错配修复基因(mismstch repair,MMR)hMLH1和hMSH2突变的相关性。方法:收集1998-04-01-2009-12-31新疆维吾尔自治区人民医院手术切除的小肠腺癌组织58例及相应的正常组织(距离癌组织>5cm),采用聚合酶链-简单序列长度多态性(PCR-SSCP)方法检测癌组织和癌旁正常组织石蜡标本DNA的MSI情况,以及hMLH1和hMSH2基因的突变情况,比较MSI组和微卫星稳定(microsatellite stability,MSS)组hMLH1和hMSH2基因突变的差异。结果:58例小肠腺癌样本中,MSI19例,占32.76%;MSS 39例,占67.24%。19例MSI中,高频率MSI(high frequency MSI,MSI-H)12例,占20.69%;低频率MSI(low frequency MSI,MSI-L)7例,占12.07%。5个微卫星位点共检出36个不稳定位点,其中BAT26的频率为30.56%(11/36),D2S123的频率为33.33%(12/36),BAT40的频率为11.11%(4/36),D17S250的频率为13.89%(5/36),D3S346的频率为11.11%(4/36)。12例MSI-H中,hMLH1基因突变6例,hMSH2基因突变1例(第7外显子突变);7例MSI-L中,2例发生hMLH1基因突变,未发现hMSH2基因突变。19例MSI中,存在hMLH1和hMSH2基因突变者9例,总突变发生率为47.37%(9/19);39例MSS中,未发现hMLH1和hMSH2基因突变,两组比较差异有统计学意义,χ2=21.87,P<0.001。结论:MSI是小肠腺癌中一个常见分子事件,hMLH1基因突变可能是导致MSI的主要原因,联合分析MSI和hMLH1及hMSH2基因突变情况对小肠腺癌的早期诊断具有重要意义。 Objective: To investigate the microsatellite instability (MSI) in small intestinal adenocarcinoma and its relationship with hMLH1 and hMSH2 mutations in mMRS. Methods: Fifty-eight cases of small bowel adenocarcinoma and corresponding normal tissues (> 5cm away from cancer) surgically removed from People’s Hospital of Xinjiang Uygur Autonomous Region from 1998-04-01 to 2009-12-31. Polymerase chain-simple sequence (MSI) and hMSH2 gene mutations in MSI group and microsatellite stability group (MSS group) were compared by PCR-SSCP method to detect the MSI of paraffin-embedded specimens of cancer tissues and adjacent normal tissues. Mutation differences. Results: In 58 samples of small intestinal adenocarcinoma, MSI was found in 19 cases (32.76%) and in 39 cases (67.24%). In 19 cases of MSI, 12 cases were high frequency MSI (MSI-H), accounting for 20.69%; 7 cases were low frequency MSI (MSI-L), accounting for 12.07%. A total of 36 loci were detected in 5 microsatellite loci, including BAT26 frequency of 30.56% (11/36), D2S123 frequency of 33.33% (12/36) and BAT40 frequency of 11.11% (4 / 36). The frequency of D17S250 was 13.89% (5/36) and the frequency of D3S346 was 11.11% (4/36). In 12 cases of MSI-H, hMLH1 gene mutation in 6 cases, hMSH2 gene mutation in 1 case (exon 7); 7 cases of MSI-L, 2 cases of hMLH1 gene mutation, hMSH2 gene mutation was not found. In 19 cases of MSI, there were 9 cases of hMLH1 and hMSH2 gene mutations, the total mutation rate was 47.37% (9/19); 39 cases of MSS, no hMLH1 and hMSH2 gene mutations were found, the difference between the two groups was statistically significant, χ2 = 21.87, P <0.001. Conclusion: MSI is a common molecular event in intestinal adenocarcinoma. The mutation of hMLH1 gene may be the main cause of MSI. The combined analysis of MSI, hMLH1 and hMSH2 gene mutations is of great significance in the early diagnosis of small intestinal adenocarcinoma.