As noted above, a polymorphism in the PAC1 receptor has been associated with PTSD symptoms (Ressler et al., 2011) and carriers of the risk allele exhibit differential hippocampal-dependent function in a contextual conditioning task compared to subjects with the normal allele (Pohlack et al., 2015). The gene discussed is ADCYAP1R1; the disease is post-traumatic stress disorder.