儿童区域性亚甲基四氢叶酸还原酶基因多态性与先天性心脏病的关系

发布时间：2018-06-02 15:26

本文选题：亚甲基四氢叶酸还原酶 + 基因多态性　；参考：《山东大学》2017年博士论文

【摘要】：引言婴幼儿出生缺陷中,先天性心脏病是最常见类型,以死亡率高、花费高,给家庭、社会带来沉重负担,尽管随着医疗保险制度的完善,患儿家庭负担在一定程度上减轻,但先天性心脏病所带来的各种影响伴随患儿一生。近些年来,随着医疗技术的进步,产前筛查的普及,先天性心脏病,尤其是复杂性先天性心脏病患儿的出生率明显降低,但如何从病因上阐明先心病发病机制,从而根本上预防先天性心脏病的发生一直是研究难点。尽管目前对先心病的研究取得了较大进步,且一刻未停,基因水平的研究也在不断深入,但完全阐明先心病的发病机制及影响因素,依然任重道远。现在比较被大多数研究者接受的理论认为,先心病的发生是一综合作用的结果,遗传基因可能起主要作用,环境因素(辐射、污染、疾病等)是影响因素。查明与先心病发生有关的基因突变,探究其基因突变原因,进而采取有针对性的预防措施,有助于降低先天性心脏病的发生。研究目的:探究沂蒙地区汉族先天性心脏病儿童亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因 C677T 的多态性分布,分析该地区汉族儿童MTHFR C677T基因与先天性心脏病发生的关联性,了解该地区汉族儿童血浆同型半胱氨酸(Hcy)浓度水平,计算分析基因与血浆Hcy浓度水平的相关程度。探讨MTHFR C677T基因在先心病发病机制中可能的作用,为先天性心脏病的病因及预防提供新线索。研究方法:选择2014年10月至2016年6月,就诊临沂市人民医院患有先天性心脏病的儿童110例作为病例组(CHD组),选择同期就诊该院查体的健康儿童110例作为对照组,两组年龄均为1-5岁,平均3.2岁,性别、年龄均无统计学差异;取两组儿童外周静脉血进行MTHFR C677T DNA提取和血浆同型半胱氨酸(Hcy)水平测定,并利用聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)方法进行基因分型,ELISA法测定血浆同型半胱氨酸水平。采用病例对照研究方法,分析基因C677T多态性与先天性心脏病发病及血浆同型半胱氨酸水平的相关性。结果:基因型CC、CT、TT,是MTHFRC677位点的三种基因型,等位基因T是突变基因;MTHFR基因C677T基因型CC、CT、TT型在CHD组和对照组的分布频率分别为0.109、0.382、0.509 和 0.50、0.409、0.091,两组间有显著统计学差异χ2=59.796,P=0.000),CHD组含T基因型频率明显高于基因型CC频率;等位基因C、T在CHD组与对照组频率分别为0.30、0.70和0.705、0.295,两组间具有显著统计学差异(χ2=72.011,P=0.000),其中CHD组等位基因T基因频率高于对照组等位基因T基因频率。含突变等位基因T的基因型患先心病的风险约是携带野生型等位基因C基因型的5.6倍(OR=5.564 95%CI3.697～8.373,P=0.000)。杂合子CT基因型患先心病的风险高于野生型纯合子基因型CC(OR=4.208,95%CI2.015～9.082,P=0.000);突变纯合子TT基因型患先心病的风险是野生型纯合子CC基因型的25.667倍(95%CI 10.249～64.276,P=0.000),纯合突变TT基因型对于先心病的致病风险大。CHD组血浆同型半胱氨酸平均水平为(15.42±0.75umol/l)明显高于对照组(7.48±0.37umol/l),MTHFR C677T基因型与血浆同型半胱氨酸水平具有相关性,Spearman相关系数为0.502。结论:沂蒙地区汉族先心病儿童和健康儿童中,MTHFR C677T基因具有多态性,其基因型频率和等位基因频率具有统计学差异(P0.05),先心病患儿中含等位基因T的基因型频率及基因频率较高;相关性分析示,突变等位基因T可能增加患先心病的风险,而突变纯合子TT基因型罹患患先心病的危险显著增加;与对照组比较,血浆Hcy浓度在儿童先心病中明显升高,并且MTHFR C677T基因与血浆Hcy浓度具有相关性,随着含T基因型比例的升高,血浆同型半胱氨酸有升高趋势。MTHFR基因C677T多态性可能是影响沂蒙地区汉族儿童罹患先天性心脏病的危险因素之一,其基因突变致心脏异常发育而引起先心病的机制复杂,推测血浆中高水平的同型半胱氨酸可能是影响因素之一。意义:该课题在设计上体现了"基因-疾病"的思路,研究群体的区域化,能够在一定程度上减小周围环境、饮食习惯等对研究结果的影响,此次研究系较早对沂蒙地区汉族儿童MTHFR C677T基因及血浆Hcy进行分析,试图探究该地区汉族儿童患先心病的相对危险基因及可能的作用机制;为从基因水平上研究先心病增加了新的认识,为高危儿童予以早期干预措施提供理论依据。符合精准医疗的发展趋势,为基因筛查、治疗提供线索。
[Abstract]:In the introduction of infant birth defects, congenital heart disease is the most common type, with high mortality, high cost and a heavy burden to the family and society. Although with the improvement of the medical insurance system, the family burden is alleviated to a certain extent, but the various effects of congenital heart disease are accompanied by the children's life. In recent years, with the medical treatment, with the medical treatment, with the medical treatment, with the medical treatment, with the medical treatment, with the medical treatment in recent years, along with the medical treatment The progress of the therapy, the popularization of prenatal screening, the birth rate of congenital heart disease, especially the children with complex congenital heart disease have been significantly reduced, but how to elucidate the pathogenesis of the congenital heart disease from the cause of the disease has been the difficulty in the study of congenital heart disease. The study of gene level is also going deep, but it is still a long way to go. It is now accepted by most researchers that the occurrence of congenital heart disease is the result of a comprehensive effect, the genetic gene may play a major role, environmental factors (radiation, pollution, disease). It is the influence factor. To find out the gene mutation related to the congenital heart disease, explore the cause of the gene mutation, and then take the pertinent preventive measures to help reduce the occurrence of congenital heart disease. The polymorphism distribution of eductase, MTHFR) gene C677T, analysis of the association between MTHFR C677T gene and congenital heart disease in Han children in this area, to understand the level of plasma homocysteine (Hcy) concentration in Han children in this area, to calculate the correlation between the analysis of gene and plasma Hcy concentration, and to explore the incidence of MTHFR C677T gene in the onset of congenital heart disease. The possible role of the mechanism to provide new clues for the cause and prevention of congenital heart disease. Methods: from October 2014 to June 2016, 110 children with congenital heart disease in Linyi people's hospital were selected as case group (group CHD), and 110 healthy children in the same period were selected as the control group, and the two groups were all aged. 1-5 years old, average 3.2 years, sex and age were not statistically different; two groups of peripheral venous blood were taken for MTHFR C677T DNA extraction and plasma homocysteine (Hcy) level, and polymerase chain reaction restriction fragment length polymorphism analysis (PCR-RFLP) method was used for genotyping and ELISA determination of plasma homocysteine The correlation between gene C677T polymorphism and congenital heart disease and plasma homocysteine levels was analyzed by case control study. Results: genotype CC, CT, TT, were three genotypes of MTHFRC677 loci and allele T was a mutant gene; MTHFR gene C677T genotype CC, CT, TT type were distributed frequency in CHD and control groups The rates were 0.109,0.382,0.509 and 0.50,0.409,0.091 respectively. There were significant statistical differences between the two groups. The frequency of T genotypes in the CHD group was significantly higher than the genotype CC frequency; the allele C and the frequency of T in the CHD group and the control group were 0.30,0.70 and 0.705,0.295. There were significant statistical differences between the two groups. The T gene frequency of the D allele was higher than the T allele frequency of the control group. The risk of congenital heart disease with the mutant allele T was about 5.6 times that of the C genotype of the wild type allele (OR=5.564 95%CI3.697 to 8.373, P=0.000). The risk of congenital heart disease in the heterozygote CT genotype was higher than that of the wild type homozygote genotype CC (OR=4.20) 8,95%CI2.015 ~ 9.082, P=0.000); the risk of congenital heart disease in the mutant homozygote TT genotype was 25.667 times that of the wild type homozygote CC genotype (95%CI 10.249 ~ 64.276, P=0.000). The average level of plasma homocysteine (15.42 + 0.75umol/l) in the large.CHD group of homozygous mutant TT genotypes was significantly higher than that of the control group (7.4 8 + 0.37umol/l), the genotype of MTHFR C677T was correlated with plasma homocysteine level, and the correlation coefficient of Spearman was 0.502. conclusion: the MTHFR C677T gene was polymorphic in the Han and healthy children of Yimeng Han and healthy children. The genotype frequency and allele frequency rate had statistical difference (P0.05), and the children with congenital heart disease contained the allele. The genotype frequency and gene frequency of the allele T were higher, and the correlation analysis showed that the mutation allele T might increase the risk of congenital heart disease, while the risk of congenital heart disease in the mutant homozygote TT genotype increased significantly. Compared with the control group, the plasma Hcy concentration was significantly higher in children with congenital heart disease, and the MTHFR C677T gene and plasma Hcy concentration were significantly higher. Degree of correlation, with the increase of T genotype ratio, the increase of plasma homocysteine trend.MTHFR gene C677T polymorphism may be one of the risk factors affecting congenital heart disease of Han children in Yimeng area. The mechanism of abnormal heart development caused by the mutation of the gene is complicated, and the high level of plasma is speculated. Homocysteine may be one of the influencing factors. Significance: the design embodies the idea of "gene disease", studies the regionalization of the population, and can reduce the influence of the surrounding environment and dietary habits to some extent. The study was earlier on the MTHFR C677T gene and plasma Hcy in the Han children in Yimeng area. In order to explore the relative risk genes and possible mechanisms of congenital heart disease in the Han children in this area, we try to provide a new understanding for the study of congenital heart disease from the gene level, and provide a theoretical basis for the early intervention measures for high risk children. It is in line with the trend of the development of precision medical treatment, and provides clues for gene screening and treatment.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：R725.4

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