In this context, the most investigated genes are those related to PTSD, belonging to the GABA and HPA axis, cortisol metabolism, brain pathways, and plasticity, and are involved in neuroendocrine stress responses; dopamine, norepinephrine, and serotonin signalling; apoptosis; insulin secretion; reproduction; and foetal growth (e.g. MAOA, BRSK2, ADCYAP1, BDNF, DRD2, IGF2, H19). This evidence concerns the gene MAOA and post-traumatic stress disorder.