However, the diurnal variation in differences of cortisol levels between PTSD and healthy subjects described by Vythilingam et al.7, as well as concurrent ACTH differences (Supplementary Figure 1b), compelled us to hypothesize that a more comprehensive analysis of circulating immune mediators, many known to be under circadian control, might identify downstream circulating biomarkers for PTSD. The gene discussed is POMC; the disease is post-traumatic stress disorder.