育龄女性MTHFR、MTRR基因多态性分布以及与血清叶酸和同型半胱氨酸水平的相关性研究

目的探讨叶酸代谢关键酶基因5,10-亚甲基四氢叶酸还原酶(MTHFR)C677T、A1298C和甲硫氨酸合成酶还原酶(MTRR)A66G多态性在育龄女性中的分布特征,并分析不同遗传特征对外周血叶酸和同型半胱氨酸(Hcy)水平的影响。方法选取2018年3月至2020年1月在上海计生所医院妇科就诊的汉族育龄女性2 651例,根据知情同意原则,采集口腔黏膜上皮脱落细胞,抽提基因组DNA,使用荧光定量PCR方法检测MTHFR C677T、A1298C和MTRR A66G基因多态性,采用化学发光法检测外周血叶酸水平,循环酶法检测血清Hcy水平。结果 (1)MTHFR C677TCC、CT、TT的基因型频率分别为33.2%、47.9%、18.9%,C、T等位基因频率分别为57.1%、42.9%;MTHFR A1298C AA、AC、CC的基因型频率分别为66.6%、30.5%、2.9%,A、C等位基因频率分别为81.8%、18.2%;MTRR A66G AA、AG、GG的基因型频率分别为56.4%、36.9%、6.8%,A、G等位基因频率分别为74.8%、25.2%。(2)MTHFR C677T和A1298C两位点连锁有7种组合,频率最高的是CT/AA(31.9%),没有CT/CC和TT/CC组合。两位点间存在完全连锁不平衡(D′=0.984,R2=0.161)。(3)MTHFR C677T不同基因型的叶酸和Hcy水平差异有统计学意义(P<0.05)。TT基因型的叶酸水平低于CC基因型,TT基因型的Hcy水平高于CC基因型。经单因素Logistic回归分析发现,MTHFR C677T TT基因型发生高Hcy血症的危险性是CC基因型的9.97倍(95%CI:3.81~26.05)。MTHFR A1298C和MTRR A66G不同基因型与血清叶酸及Hcy水平差异无统计学意义(P>0.05)。(4)经单因素回归分析,Hcy水平与叶酸水平呈负相关(R2=0.061,P<0.05),叶酸水平可解释Hcy水平个体差异的6.1%。结论获取了上海市汉族育龄女性MTHFR和MTRR基因多态性的群体遗传学特征,血清Hcy水平与MTHFR C677T基因多态性以及血清叶酸水平有关。筛查MTHFR和MTRR基因多态性并监测Hcy水平对围生期保健有重要的指导意义。

Study on distribution of MTHFR and MTRR gene polymorphisms and their correlation with serum folic acid and homocysteine levels in women of childbearing age

Objective To investigate the distribution characteristics of 5,10-methylenetetrahydrofolate reductase(MTHFR)C677T,A1298C and methionine synthase reductase(MTRR)A66G polymorphism in women of childbearing age,and to analyze the influence of different genetic characteristics on the levels of folic acid and homocysteine(Hcy)in peripheral blood.Methods A total of 2651 Han women of childbearing age in the gynecology department of the Shanghai Family Planning Institute Hospital from March 2018 to January 2020 were selected.According to the principle of informed consent,the epithelial exfoliated cells of oral mucosa were collected,and the genomic DNA was extracted.The MTHFR C677T,A1298C and MTRR A66G gene polymorphisms were detected by fluorescence quantitative PCR.The folic acid level in peripheral blood was detected by chemiluminescence.The Hcy level in serum was detected by the circulating enzyme method.Results(1)The genotype frequencies of MTHFR C677T CC,CT and TT were 33.2%,47.9%and 18.9%,respectively,and the allele frequencies of C and T were 57.1%and 42.9%,respectively;the genotype frequencies of MTHFR A1298C AA,AC and CC were 66.6%,30.5%and 2.9%,and the allele frequencies of A and C were 81.8%and 18.2%,respectively.The genotype frequencies of MTRR A66G AA,AG and GG were 56.4%,36.9%and 6.8%respectively,and the allele frequencies of A and G were 74.8%and 25.2%respectively.(2)The two sites linkage of MTHFR C677T and A1298C had seven combinations,in which the highest frequency was CT/AA(31.9%).And there was no combination of CT/CC and TT/CC.There existed complete linkage disequilibrium between the two loci(D′=0.984,R 2=0.161).(3)The levels of folate and Hcy in different genotypes of MTHFR C677T had statistically significantly difference(P<0.05).The folic acid level of TT genotype was lower than that of CC genotype,and the Hcy level of TT genotype was higher than that of CC genotype.The single factor logistic regression analysis showed that the risk of hyperhomocysteinemia in MTHFR C677T TT genotype was 9.97 times that of CC genotype(95%CI:3.81-26.05).There was no statistically significant difference in folic acid and Hcy levels between MTHFR A1298C and MTRR A66G genotypes(P>0.05).(4)After the univariate regression analysis,the Hcy level was negatively correlated with the folic acid level(R 2=0.061,P<0.05),and the folic acid level could explain 6.1%of the individual differences in the Hcy level.Conclusion The population genetic characteristics of MTHFR and MTRR gene polymorphisms are obtained in Shanghai Han women of childbearing age.The serum Hcy level is related to MTHFR C677T gene polymorphisms and serum folic acid level.Screening MTHFR and MTRR gene polymorphisms and monitoring Hcy level are of great significance for perinatal health care.