MC4R and obesity due to melanocortin 4 receptor deficiency: In conclusion, we have shown that MC4R agonists increase the HCVR, increase minute ventilation during sleep and wakefulness, and abolish apneas and oxyhemoglobin desaturations during sleep, treating sleep-disordered breathing in obesity, and that the respiratory effects of MC4R agonists occur in the parafacial region, possibly in the RTN.