To examine the heritabilities of symptoms of posttraumatic stress disorder (PTSD), anxiety, depression, and the shared genetic component of these symptoms among family members exposed to the 1988 Spitak earthquake in Armenia.
Two hundred members of 12 multigenerational families exposed to the Spitak earthquake were studied using a battery that assessed earthquake exposure and symptoms of PTSD, anxiety, and depression. Heritabilities of these phenotypes were determined using variance component analyses and shared genetic vulnerabilities between these phenotypes were determined using bivariate analyses.
Heritabilities were as follows: PTSD symptoms 41% (P<0.001), anxiety symptoms 61% (P<0.001), and depressive symptoms 66% (P<0.001). The genetic correlation (ρg>0) of PTSD symptoms with anxiety symptoms was 0.75 (P<0.001) and with depressive symptoms it was 0.71 (P<0.001). The genetic correlation of anxiety with depressive symptoms was 0.54 (P<0.001).
The heritabilities found in this multigenerational family study indicate that the genetic make-up of some individuals renders them substantially more vulnerable than others to develop symptoms of PTSD, anxiety, and depression. A large proportion of the genetic liability for PTSD, anxiety, and depression are shared. The findings offer promise for identifying susceptibility genes for these phenotypes.