In addition to the requisite etiological factor of trauma exposure for its onset, the abnormal expression of and functional changes in some neurotransmitters and neurotrophins, such as dopamine, serotonin, and brain‐derived neurotrophic factor (BDNF), are considered the most important factors that contribute to PTSD susceptibility (Miller et al., 2017; Rakofsky et al., 2012). The gene discussed is BDNF; the disease is post-traumatic stress disorder.