CRHR2 and myalgic encephalomeyelitis/chronic fatigue syndrome: CRFR2 can fail to downregulate, influenced by defects in threat response-related genes (Goertzel et al., 2006) and female sex (Bangasser et al., 2010, 2013; Bangasser, 2013; Howerton et al., 2014; Weathington et al., 2014; Lukkes et al., 2016), effectively changing the homeostatic set point, leading to 5HT deregulation, lost homeostasis, and the persistent signs and symptoms of ME/CFS.