In support of the ability to sense metabolic changes, the MHb is known to specifically express the orphan G-protein coupled receptor Gpr151, which functions to limit nicotine intake (Antolin-Fontes et al., 2020), and individuals from the UK Biobank cohort who are heterozygous for loss of function alleles of Gpr151 have decreased risk of obesity and diabetes (Emdin et al., 2018). The gene discussed is GPR151; the disease is obesity due to melanocortin 4 receptor deficiency.