DRD2 and obesity due to melanocortin 4 receptor deficiency: This contrasts with what was observed by Epstein et al. (2007) who evaluated food reinforcement, genetic variants of DRD2 (rs1800497), and energy intake in individuals with obesity and non-obese humans and observed that energy intake was higher in individuals with high food reinforcement and even greater in those carriers of the TaqI A1 allele.