BACKGROUND Epigenetic mechanisms have been suggested to play a role in the development of post-traumatic stress disorder (PTSD). Here, blood-derived DNA methylation data (HumanMethylation450 BeadChip) collected prior to and following combat exposure in three cohorts of male military members were analyzed to assess whether DNA methylation profiles are associated with the development of PTSD. A total of 123 PTSD cases and 143 trauma-exposed controls were included in the analyses. The Psychiatric Genomics Consortium (PGC) PTSD EWAS QC pipeline was used on all cohorts, and results were combined using a sample size weighted meta-analysis in a two-stage design. In stage one, we jointly analyzed data of two new cohorts (N = 126 and 78) for gene discovery, and sought to replicate significant findings in a third, previously published cohort (N = 62) to assess the robustness of our results. In stage 2, we aimed at maximizing power for gene discovery by combining all three cohorts in a meta-analysis. RESULTS Stage 1 analyses identified four CpG sites in which, conditional on pre-deployment DNA methylation, post-deployment DNA methylation was significantly associated with PTSD status after epigenome-wide adjustment for multiple comparisons. The most significant (intergenic) CpG cg05656210 (p = 1.0 × 10-08) was located on 5q31 and significantly replicated in the third cohort. In addition, 19 differentially methylated regions (DMRs) were identified, but failed replication. Stage 2 analyses identified three epigenome-wide significant CpGs, the intergenic CpG cg05656210 and two additional CpGs located in MAD1L1 (cg12169700) and HEXDC (cg20756026). Interestingly, cg12169700 had an underlying single nucleotide polymorphism (SNP) which was located within the same LD block as a recently identified PTSD-associated SNP in MAD1L1. Stage 2 analyses further identified 12 significant differential methylated regions (DMRs), 1 of which was located in MAD1L1 and 4 were situated in the human leukocyte antigen (HLA) region. CONCLUSIONS This study suggests that the development of combat-related PTSD is associated with distinct methylation patterns in several genomic positions and regions. Our most prominent findings suggest the involvement of the immune system through the HLA region and HEXDC, and MAD1L1 which was previously associated with PTSD.

中文翻译：

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对三个男性军人的纵向表观基因组范围的关联研究揭示了与创伤后应激障碍相关的多个CpG位点。

背景技术已经提出表观遗传机制在创伤后应激障碍（PTSD）的发展中起作用。在这里，分析了在三个战役的男性军人中，在战役暴露之前和之后收集的血液来源的DNA甲基化数据（HumanMethylation450 BeadChip），以评估DNA甲基化谱是否与PTSD的发生有关。分析总共包括123例PTSD病例和143例暴露于创伤的对照。精神病基因组学联盟（PGC）的PTSD EWAS QC管线用于所有队列，并在两个阶段的设计中使用样本大小加权荟萃分析合并结果。在第一阶段，我们共同分析了两个新的队列研究数据（N = 126和78）以进行基因发现，并试图在第三个队列中复制重要发现，先前发表的队列（N = 62）来评估我们结果的稳健性。在第2阶段中，我们的目标是通过在荟萃分析中结合所有这三个队列来最大化基因发现的能力。结果第1阶段的分析确定了四个CpG位点，其中在以表观基因组范围进行多次比较调整后，以部署前DNA甲基化为条件，部署后DNA甲基化与PTSD状态显着相关。最重要的（基因间的）CpG cg05656210（p = 1.0×10-08）位于5q31处，并在第三个队列中明显复制。此外，鉴定出19个差异甲基化区域（DMR），但复制失败。第2阶段分析确定了三个表观基因组范围内的重要CpG，基因间CpG cg05656210和位于MAD1L1（cg12169700）和HEXDC（cg20756026）中的两个其他CpG。有趣的是 cg12169700具有潜在的单核苷酸多态性（SNP），该位点与MAD1L1中最近发现的与PTSD相关的SNP位于同一LD嵌段内。第2阶段分析进一步确定了12个重要的差异甲基化区域（DMR），其中1个位于MAD1L1中，而4个位于人白细胞抗原（HLA）地区。结论这项研究表明，与战斗有关的创伤后应激障碍的发展与在几个基因组位置和区域的明显甲基化模式有关。我们最突出的发现表明免疫系统通过HLA区和HEXDC以及先前与PTSD相关的MAD1L1参与了该过程。第2阶段分析进一步确定了12个重要的差异甲基化区域（DMR），其中1个位于MAD1L1中，而4个位于人白细胞抗原（HLA）地区。结论这项研究表明，与战斗有关的创伤后应激障碍的发展与在几个基因组位置和区域的明显甲基化模式有关。我们最突出的发现表明免疫系统通过HLA区和HEXDC以及先前与PTSD相关的MAD1L1参与了该过程。第2阶段分析进一步确定了12个重要的差异甲基化区域（DMR），其中1个位于MAD1L1中，而4个位于人白细胞抗原（HLA）地区。结论这项研究表明，与战斗有关的创伤后应激障碍的发展与在几个基因组位置和区域的明显甲基化模式有关。我们最突出的发现表明免疫系统通过HLA区和HEXDC以及先前与PTSD相关的MAD1L1参与了该过程。结论这项研究表明，与战斗有关的创伤后应激障碍的发展与在几个基因组位置和区域的明显甲基化模式有关。我们最突出的发现表明免疫系统通过HLA区和HEXDC以及先前与PTSD相关的MAD1L1参与了该过程。结论这项研究表明，与战斗有关的创伤后应激障碍的发展与在几个基因组位置和区域的明显甲基化模式有关。我们最突出的发现表明免疫系统通过HLA区和HEXDC以及先前与PTSD相关的MAD1L1参与了该过程。