课题采用病例-对照研究探索宫内重金属暴露、DNA甲基化和非综合征室间隔缺损(NsVSD)的关系。主要内容1）环境暴露研究:检测200对病例和对照胎盘组织铅汞镉含量,关联分析鉴别主要污染物；2)DNA甲基化研究:根据主要污染物水平选取40例对照，NimbleGen CpG Promoter甲基化芯片检测脐血/胎盘DNA，筛选暴露敏感甲基化位点各5个；同时从LINE-1/Alu序列、心脏发育和一碳代谢基因中选约10个目标CpG区域；Sequenom MassArray Methylation技术检测全部病例和对照的胎盘及脐血DNA目标区域甲基化水平，确定NsVSD相关联的位点；3）视标本收集情况，拟用20例无畸形引产胎儿的胎盘/脐血和心脏组织DNA分析NsVSD风险位点甲基化水平的相关性，评价脐血/胎盘甲基化标记在人群CHD研究中的适用性。Logistic回归探讨暴露、DNA甲基化对畸形风险的影响及可能机制。

A case-control study will be used to investigate the relationship between intrauterine exposures to selected heavy metals, DNA methylation changes of related genes, and the risk of nonsyndromic ventricular septal defects (NsVSD). The main contents are as follows：1)Envrionmental exposure study: the placental lead (Pb), mercury (Hg) and cadmium (Cd) of 200 NsVSD cases and 200 controls will be assessed, and the assocition of heavy metal exposure with NsVSD will be analyzed, and then to decide which one is the major pollutant. 2)DNA methylation study: According to different concentration levels of major heavy metal in control groups, 40 control infants will be selected and their genomic methylation of cord blood DNA and placenta DNA will be examined by NimbleGen CpG Promoter Assay to screen out 5 candidate loci for each type of tissue that are prone to methylation changes with prenatal heavy metal exposures. In addtion, about ten target regions including LINE-1/Alu repetitive elements, CpG islands in genes implicated in fetal heart development and one-carbon-related metabolisms,will be selected as candidate loci for DNA methylation analysis. Using the Sequenom MassArray Methylation platform, DNA methylation of these CpG sites in cord blood and placenta tissues will be detected for all cases and controls, and the relationship between loci-specific methylation and NsVSD will be evaluated, thus loci related to NsVSD risk will be identified for the next analysis.3) Using DNA samples extracted from cord blood, placenta and heart tissues of 20 aborted fetus without heart defects, the correlation of NsVSD-related loci-specific methylation between three different tissue DNA specimens will be assessed, then the applicability of methylation changes in cord blood and placenta tissues as surrogate marks in human CHD studies will be assessed. It is noteworthy that this part of research depends on the availability of tissue samples. Data from above studies will be incorporated into logistic regression models to explore the independent and combined effects of intrauterine Pb,Hg and Cd exposures, DNA methylation alterations on CHD risk, and possible mechanisms.