Regarding the “construct validity” criterion (Fig. 5), while it is not yet known why certain individuals develop PTSD after a traumatic event while others do not, it remains worth assessing this validity criterion around some of the most accepted hypotheses concerning PTSD pathophysiology, and numerous authors suggest relations between BDNF, inflammation, and PTSD predisposition95,96. The gene discussed is BDNF; the disease is post-traumatic stress disorder.