The potential role of the ghrelin system is further underscored by the notion that mood-, anxiety- and trauma-related disorders are often associated with metabolic dysregulation and also show a high level of comorbidity with obesity or eating disorders (Scott et al., 2008; Ng et al., 2013; Mason et al., 2014; Meng and D’Arcy, 2015; Aaseth et al., 2019). The gene discussed is GHRL; the disease is obesity due to melanocortin 4 receptor deficiency.