APC基因MCR区突变与大肠肿瘤患者临床发病的关系

Correlation of APC MCR mutation with colorectal neoplasms

目的:探讨APC基因的第15外显子MCR区(mutation cluster region)的1493,1367和1328位突变与大肠肿瘤患者(阳性家族史)临床发病的关系.方法:共提取65例标本的基因组DNA,包括21例肠腺瘤标本组和16例肠腺癌标本组,20例家族史阳性组和8例无家族史组.PCR特异性扩增APC基因的第15外显子MCR区,经ABI3100基因测序仪测序,对密码子突变情况按4个标本分组和基因变异类型进行统计分析.结果:检出APC基因的三种密码子突变,即密码子1493(ACG>ACA),突变的发生率为91.3%(63/69),密码子1367(CAG>TAG),1.4%(1/69)和密码子1328(CAG>TAG),7.2%(5/69).共检出4种碱基变化,4478(G→A),4478(G/A),4096(C/T)and3979(C/T).4478位碱基G→A和4478位碱基G/A分别在腺瘤组与无家族史组的比较有显著性差异(P<0.05),4478位碱基G→A在家族史阳性组与无家族史组的比较也有显著性差异(P<0.05).基于临床病理突变表型,四种核苷酸变化间经χ2检验比较发现有显著性差异(P<0.05)的是:4478位G→A型突变分别与4478位G/A型突变、4096位C/T型突变和3979位C/T型突变之间,4478位碱基G/A型突变分别与4096位C/T型突变和3979位C/T型突变之间,而4096位C/T型突变和3979位C/T型突变比较无显著性意义.结论:密码子1493(ACG>ACA)的4478位(G→A)突变为各组最高频发的同义突变,与阳性家族史和腺瘤表型有关.密码子1367(CAG>TAG)和1328(CAG>TAG)仅为腺癌表型的体细胞无义突变.

AIM： To explore relationship of codon 1493, 1367 and 1328 mutations in mutation cluster region （MCR） of exon 15 of Adenomatous polyposis coli （APC） gene in cases of colorectal neoplasm with the family history. METHODS： The specimens were prepared for DNA extraction from 21 colorectal adenoma specimens, 16 colorectal carcinoma, 20 healthy germline groups with positive familial history and 8 healthy germline groups without family history, Then MCR of APC gene exon 15 were specifically amplified and sequenced by ABI3100 Genetic Analyzer, and the codon mutations were statistically analyzed among the 4 groups and variation genotypes, and then tested with Chi-square. RESULTS： The codon mutations of APC MCR from total samples were three variations： 1493（ACG〉ACA）, 63/69（91.3%）; 1367（CAG〉TAG）, 1/69（1.4%） and 1328（CAG〉TAG）, 5/69（7.2%）Four genotypes such as 4478 （G→A）, 4478 （G/A）, 4096 （C/T） and 3979 （C/T） were found out. Significant differences （P 〈 0.05） were noted between the adenoma group and non-family history group on the analysis of 4478 （G→A） and （G/A）, also noted between family history group and no family history group on the analysis of 4478 （G→A）. The significant differences （P 〈 0.05） in pathogenic mutant phenotypes were involved between 4478 （G →A） with 4478 （G/A）, 4096 （C/T） and 3979 （C/T）, respectively, also between 4478 （G/A） with 4096 （C/T） and 3979 （C/T）, but not between 4096 （C/T） and 3979 （C/T）. CONCLUSION： The most frequently present 4478 （G→A） of 1493 （ACG〉ACA） is the phenotype of positive history group and adenoma group. In researches, APC MCR codon 1367 and 1328 genotyping are significantly present only in somatic cells of the colorectal cancergenetic phenotypes.