Genome-wide Association Study Identifies New Susceptibility Loci for Posttraumatic Stress Disorder

Abstract

Background Genetic factors influence the risk for posttraumatic stress disorder (PTSD), a potentially chronic and disabling psychiatric disorder that can arise after exposure to trauma. Candidate gene association studies have identified few genetic variants that contribute to PTSD risk. Methods We conducted genome-wide association analyses in 1578 European Americans (EAs), including 300 PTSD cases, and 2766 African Americans, including 444 PTSD cases, to find novel common risk alleles for PTSD. We used the Illumina Omni1-Quad microarray, which yielded approximately 870,000 single nucleotide polymorphisms (SNPs) suitable for analysis. Results In EAs, we observed that one SNP on chromosome 7p12, rs406001, exceeded genome-wide significance (p = 3.97×10−8). A SNP that maps to the first intron of the Tolloid-Like 1 gene (TLL1) showed the second strongest evidence of association, although no SNPs at this locus reached genome-wide significance. We then tested six SNPs in an independent sample of nearly 2000 EAs and successfully replicated the association findings for two SNPs in the first intron of TLL1, rs6812849 and rs7691872, with p values of 6.3×10−6 and 2.3×10−4, respectively. In the combined sample, rs6812849 had a p value of 3.1 ×10−9. No significant signals were observed in the African American part of the sample. Genome-wide association study analyses restricted to trauma-exposed individuals yielded very similar results. Conclusions This study identified TLL1 as a new susceptibility gene for PTSD.

Genomic predictors of combat stress vulnerability and resilience in U.S. Marines: A genome-wide association study across multiple ancestries implicates PRTFDC1 as a potential PTSD gene

“…However, the association of rs6812849 in TLL1 (Xie et al, 2013) was originally detected in a larger study, and rs10170218 in LINC01090 (Guffanti et al, 2013) was originally found in an all-female AA cohort, which was also larger than the all-male MRS AA cohort, and MRS findings for these genes remain inconclusive.…”

“…We also compiled a list of genes that have been reported in the literature to be significantly associated with PTSD, either showing a main effect for the genetic marker, and/or a significant GxE interaction (Amstadter et al, 2009(Amstadter et al, , 2011Binder et al, 2008;Boscarino et al, 2011;Cao et al, 2013;Comings et al, 1996;Dragan and Oniszczenko, 2009;Gillespie et al, 2013;Goenjian et al, 2012;Grabe et al, 2009;Guffanti et al, 2013;Hauer et al, 2011;Kolassa et al, 2010;Logue et al, 2013a,b;Lyons et al, 2013;Mellman et al, 2009;Nelson et al, 2009;Ressler et al, 2011;Segman et al, 2002;Solovieff et al, 2014;Voisey et al, 2010;Wilker et al, 2013;Xie et al, 2013). Since most studies were performed in subjects of either European or African descent, we used these specific ancestry groups for comparison with MRS. We found that most of the 25 candidate genes showed nominally significant associations in MRS for at least one of the SNPs tested.…”

“…Most of the genes were identified in candidate gene studies, but LINC01090 (Guffanti et al, 2013), RORA (Logue et al, 2013a), and TLL1 (Xie et al, 2013) came from recent GWASs, thus meeting the stricter level for genome-wide significance in the original studies. We first investigated the specific SNP reported in the literature and found that none of the reported SNPs were nominally significant in the MRS EA or AA subgroups.…”

“…Most research has focused on: (1) the hypothalamic-pituitary-adrenal (HPA) axis, (2) the ascending brainstem locus coeruleus noradrenergic system, and (3) the limbic amygdalar frontal pathway mediating fear processing. Among the over 25 PTSD candidate genes currently reported (Amstadter et al, 2009(Amstadter et al, , 2011Binder et al, 2008;Boscarino et al, 2011;Cao et al, 2013;Comings et al, 1996;Dragan and Oniszczenko, 2009;Gillespie et al, 2013;Goenjian et al, 2012;Grabe et al, 2009;Guffanti et al, 2013;Hauer et al, 2011;Kolassa et al, 2010;Logue et al, 2013a,b;Lyons et al, 2013;Mellman et al, 2009;Nelson et al, 2009;Ressler et al, 2011;Segman et al, 2002;Solovieff et al, 2014;Voisey et al, 2010;Wilker et al, 2013;Xie et al, 2013), promising findings include associations of PTSD symptoms with the serotonin transporter gene (SERT, SLC6A4) (Xie et al, 2009), which is linked to depression and anxiety disorders, as well as differential acquisition of conditioned fear and increased amygdala excitability in humans. In addition, FKBP5, a co-chaperone of the glucocorticoid receptor involved in the HPA axis, has a significant interaction with severity of child abuse in the prediction of adult PTSD symptoms, indicating a gene by environment (GxE) interaction (Binder et al, 2008).…”

“…The first study on European American (EA) military veterans and their intimate partners identified the retinoid-related orphan receptor alpha (RORA) as a potential PTSD gene (Logue et al, 2013a). The second study, including EAs recruited for substance abuse, identified the Tolloid-Like 1 gene (TLL1) (Xie et al, 2013), and the third, a study in primarily African American women, implicated a lincRNA (LINC01090, alias AC068718.1) as a risk factor for PTSD (Guffanti et al, 2013).…”