title: Association study of trauma load and SLC6A4 promoter polymorphism in posttraumatic stress disorder: evidence from survivors of the Rwandan genocide.
abstract: OBJECTIVE
  As exposure to different types of traumatic stressors increases, the occurrence of posttraumatic stress disorder (PTSD) increases. However, because some people exhibit either surprising resilience or high vulnerability, further influencing factors have been conjectured, such as gene-environment interactions. The SLC6A4 gene, which encodes serotonin transporter, has been identified as predisposing toward differential emotional processing between genotypes of its promoter polymorphism.
  
  
  METHODS
  We investigated 408 refugees from the Rwandan genocide and assessed lifetime exposure to traumatic events, PTSD (according to DSM-IV) status, and genotype of the SLC6A4 promoter polymorphism. The study was conducted from March 2006 to February 2007.
  
  
  RESULTS
  The prevalence of PTSD approached 100% when traumatic exposure reached extreme levels. However, persons homozygous for the short allele of the SLC6A4 promoter polymorphism showed no dose-response relationship but were at high risk for developing PTSD after very few traumatic events. This genotype influence vanished with increasing exposure to traumatic stressors.
  
  
  CONCLUSIONS
  We find evidence for a gene-environment interplay for PTSD and show that genetic influences lose importance when environmental factors cause an extremely high trauma burden to an individual. In the future, it may be important to determine whether the effectiveness of therapeutic interventions in PTSD is also modulated by the SLC6A4 genotype.
authors.affiliation: Clinical Psychology and Neuropsychology and Zukunftskolleg, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany. Iris.Kolassa@uni-konstanz.de
authors.forename: Iris-Tatjana
authors.initials: IT
authors.lastname: Kolassa
authors.forename: Verena
authors.initials: V
authors.lastname: Ertl
authors.forename: Cindy
authors.initials: C
authors.lastname: Eckart
authors.forename: Franka
authors.initials: F
authors.lastname: Glöckner
authors.forename: Stephan
authors.initials: S
authors.lastname: Kolassa
authors.forename: Andreas
authors.initials: A
authors.lastname: Papassotiropoulos
authors.forename: Dominique J-F
authors.initials: DJ
authors.lastname: de Quervain
authors.forename: Thomas
authors.initials: T
authors.lastname: Elbert
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006708:Homicide / Q000523:psychology*; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D011569:Psychiatric Status Rating Scales; D012432:Rwanda; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D013313:Stress Disorders, Post-Traumatic / Q000235:genetics* / Q000523:psychology; D013315:Stress, Psychological / Q000235:genetics* / Q000523:psychology; D017741:Survivors / Q000523:psychology*; D055815:Young Adult
chemical_list: C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins