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目的探讨MGMT基因5’侧翼区及第一编码区多态性单体型在天然放射性高本底地区汉族人群中的分布特征。方法随机选取60例广东高本底地区汉族人群为研究对象,以人MGMT基因目的片段(-875nt~+362nt)中-797G>A、-245T>G、-177T>G、-19C>T、+73C>T和+336G>A共6个多态性位点纳入本研究,采用HaploView软件分析其遗传学特征、连锁不平衡和单体型分布。结果60例高本底地区人群中各遗传多态性位点基因型频率均符合Hardy-Weinberg平衡(P>0.05);各位点在该人群的杂合度不同,分别为-797G>A(0.208)、-245T>G(0.017)、-177T>G(0.049)、-19C>T(0.269)、+73C>T(0.269)和+336G>A(0.417),且-245T>G和-177T>G均不存在变异纯合基因型;连锁不平衡分析结果表明-797G>A与-19C>T、-797G>A与+73C>T均呈较强的连锁不平衡关系,-19C>T与+73C>T之间呈完全连锁不平衡关系。构建了该人群中5种多态性单体型,其中最主要的野生单体型(H1)频率为51.4%,其他4种为变异单体型(H2~H5),频率为46.3%。-19C>T与+73C>T之间形成1个单体型域,构成2种代表性域内单体型(CC/TT)。结论首次确认并报道广东天然放射性高本底地区汉族人群中MGMT基因5’侧翼区和第一编码区6个遗传多态性位点及其单体型(域)分布。
Objective To investigate the distribution of 5 ’flanking region and the first coding region polymorphism of MGMT gene in Han population of natural high radioactive background area. Methods Sixty Chinese Han population with high background in Guangdong were selected as the research object. The expression of -797G> A, -245T> G, -177T> G and -19C> T in the target fragment of human MGMT gene (-875nt ~ + 362nt) + 73C> T and + 336G> A were included in this study. HaploView software was used to analyze the genetic characteristics, linkage disequilibrium and haplotype distribution. Results The genotype frequency of each genetic polymorphism locus in 60 high background areas was in accordance with Hardy-Weinberg equilibrium (P> 0.05). The heterozygosity of each locus in this population was -797G> A (0.208) -245T> G (0.017), -177T> G (0.049), -19C> T (0.269), +73 C> T (0.269) and + 336G> A (0.417) G homozygous genotypes did not exist; linkage disequilibrium analysis showed that -797G> A and -19C> T, -797G> A and +73 C> T showed a strong linkage disequilibrium, -19C> T and + 73C> T between the chain was completely unbalanced relationship. Five polymorphic haplotypes were constructed in this population. The frequency of the most common haplotype (H1) was 51.4% and that of the other four species was H2 ~ H5 with a frequency of 46.3%. One haplotype domain was formed between -19C> T and + 73C> T, forming two representative domain haplotypes (CC / TT). Conclusions The genetic polymorphisms of the 5 ’flanking region and the first coding region of MGMT gene and their haplotype distribution in Han population with high background in natural radioactive areas of Guangdong were confirmed and reported for the first time.