Htr2a was upregulated in the ARC of diet-induced obese rats (Park et al., 1999), whereas in humans, 5-HT2AR correlated positively with BMI and a polymorphism in the gene encoding 5-HT2AR has been associated with obesity (Rosmond et al., 2002; Erritzoe et al., 2009; Carr et al., 2013). The gene discussed is HTR2A; the disease is obesity due to melanocortin 4 receptor deficiency.