以表型不一致双生子为基础的高血压DNA甲基化研究

DNA methylation mechanism in the pathogenesis of hypertension has not been fully elucidated. The existed evidence is mostly provided by animal experiments or in vitro studies, which needs urgently to be verified in human beings. Twins, especially Monozygotic (MZ) twin pairs which have the same genes and share their early environments, are the ideal samples for DNA methylation study. However, DNA methylation studies for essential hypertension in twins are very rare due to the difficulties in sample recruitment. .In this study, we will select 50 MZ discordant twin pairs in which one twin is suffering from essential hypertension while the other is not in the Chinese National Twin Registry which have recruited almost 20,000 twin pairs in Shandong, Zhejiang, Jiangsu and Sichuan; use the design of case co-twin control study (pair matched case-control study); explore the DNA methylation marker and its methylation level which is related to hypertension after controlling the genetic background and early environment. For replication, we will select two groups: 61 essential hypertension concordant MZ twin pairs and 50 MZ twin pairs both of which are non-essential hypertension patients. This study will be the first attempt of DNA methylation analysis in MZ twin pairs for essential hypertension in China.

目前DNA甲基化在高血压病发生发展中的机制尚未完全阐明，研究多基于动物实验或体外培养，亟待在人群中进行验证。双生子，特别是同卵双生子由于其遗传基础及早期环境完全相同，是DNA甲基化研究的理想对象，但目前利用双生子进行高血压相关DNA甲基化研究由于样本难以获得而少有人问津。.本研究在中国双生子登记系统于山东、浙江、江苏、四川四省近2万对登记双生子的基础上，选择一人患有原发性高血压、另一人不患有该病的50对不一致同卵双生子这样得天独厚的资源，利用病例-双生子同胞对照（1:1匹配病例对照）设计，探索在控制遗传和早期环境的前提下，全基因组范围内哪些基因的甲基化水平与原发性高血压相关。对于探索的结果，将采用两组人群进行双重验证，一组是双方均患有原发性高血压的61对同卵双生子，一组是双方均不患有该病的50对同卵双生子。本研究将是我国利用同卵双生子进行原发性高血压相关DNA甲基化探索的首次尝试。

本研究以中国双生子登记系统募集成年双生子为主要研究对象，以104名双生子作为甲基化阳性位点的发现人群，并收集152名双生子作为阳性位点的验证人群。通过问卷调查收集双生子个人及家庭信息，体格检查收集血压、身高、体重等信息，发现人群选用Illumina Human Methylation EPIC BeadChip芯片进行全基因组甲基化检测。在发现人群中，采用混合效应模型分析血压指标与DNA甲基化的相关性，采用经验贝叶斯调整配对t检验分析及经验贝叶斯调整的Levene检验进行高血压不一致同卵双生子对的甲基化位点分析。然后对所发现的阳性位点在验证人群中再次进行验证分析。.利用43对高血压不一致同卵双生子进行经验贝叶斯配对调整的t检验，在血压差异≥20mmHg的双生子对两种模型中共发现4个疑似阳性CpG位点与高血压相关：cg00950476，cg08041400，cg26733338，cg08580087，所在基因与转录调控、学习认知、神经发育等功能相关。由于同卵双生子遗传的高度匹配，这些CpG位点可能是环境可干预的靶点，但是仍需更大样本的高血压不一致同卵双生子研究进行验证。