The risk of posttraumatic stress disorder after trauma depends on traumatic load and the catechol-o-methyltransferase Val(158)Met polymorphism

Biol Psychiatry. 2010 Feb 15;67(4):304-8. doi: 10.1016/j.biopsych.2009.10.009. Epub 2009 Nov 27.


Background: The risk for posttraumatic stress disorder (PTSD) depends on the number of traumatic event types experienced in a dose-response relationship, but genetic factors are known to also influence the risk of PTSD. The catechol-O-methyltransferase (COMT) Val158Met polymorphism has been found to affect fear extinction and might play a role in the etiology of anxiety disorders.

Methods: Traumatic load and lifetime and current diagnosis of PTSD and COMT genotype were assessed in a sample of 424 survivors of the Rwandan Genocide living in the Nakivale refugee camp in southwestern Uganda.

Results: Higher numbers of different lifetime traumatic event types led to a higher prevalence of lifetime PTSD in a dose-response relationship. However, this effect was modulated by the COMT genotype: whereas Val allele carriers showed the typical dose-response relationship, Met/Met homozygotes exhibited a high risk for PTSD independently of the severity of traumatic load.

Conclusions: The present findings indicate a gene-environment interaction between the human COMT Val158Met polymorphism and the number of traumatic event types experienced in the risk of developing PTSD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Africa
  • Aged
  • Catechol O-Methyltransferase / genetics*
  • Chi-Square Distribution
  • Female
  • Genetic Predisposition to Disease*
  • Humans
  • Life Change Events
  • Male
  • Methionine / genetics*
  • Middle Aged
  • Polymorphism, Single Nucleotide*
  • Probability
  • Risk Factors
  • Stress Disorders, Post-Traumatic / genetics*
  • Valine / genetics*
  • Young Adult


  • Methionine
  • Catechol O-Methyltransferase
  • Valine