title: DNA methylation in repetitive elements and post-traumatic stress disorder: a case-control study of US military service members.
abstract: OBJECTIVE
  We investigated serum DNA methylation patterns in genomic repetitive elements, LINE-1 and Alu, for post-traumatic stress disorder (PTSD) cases and controls who were US military service members recently deployed to Afghanistan or Iraq.
  
  
  METHODS
  Cases (n = 75) had a postdeployment diagnosis of PTSD. Controls (n = 75) were randomly selected service members with no postdeployment PTSD diagnosis. Pre- and post-deployment sera were accessed, DNA was extracted and DNA methylation (percentage 5-methyl cytosine) was quantified via pyrosequencing. Conditional and unconditional logistic regressions were used to compare: cases post- to pre-deployment; controls post- to pre-deployment; cases to controls predeployment; cases to controls postdeployment.
  
  
  RESULTS
  LINE-1 was hypermethylated in controls post- versus pre-deployment (odds ratio [OR]: 1.33; 95% CI: 1.06-1.65) and hypomethylated in cases versus controls postdeployment (OR: 0.82; 95% CI: 0.67-1.01). Alu was hypermethylated for cases versus controls predeployment (OR: 1.46; 95% CI: 1.08-1.97).
  
  
  CONCLUSIONS
  Patterns of hypermethylation of LINE-1 in controls postdeployment and of Alu in cases postdeployment are intriguing and may suggest resilience or vulnerability factors.
authors.affiliation: Department of Preventive Medicine, Uniformed Services University, Bethesda, MD, USA. jrusiecki@usuhs.mil
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Rusiecki
authors.forename: Ligong
authors.initials: L
authors.lastname: Chen
authors.forename: Vasantha
authors.initials: V
authors.lastname: Srikantan
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Liying
authors.initials: L
authors.lastname: Yan
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Polin
authors.forename: Andrea
authors.initials: A
authors.lastname: Baccarelli
mesh_terms: D000328:Adult; D020087:Alu Elements / Q000235:genetics*; D016022:Case-Control Studies; D004247:DNA / Q000032:analysis* / Q000097:blood / Q000302:isolation & purification; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D016015:Logistic Models; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics*; D008297:Male; D008889:Military Personnel; D016017:Odds Ratio; D017422:Sequence Analysis, DNA; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism*; D014481:United States; D055815:Young Adult
chemical_list: D004247:DNA