MCHR1 and obesity due to melanocortin 4 receptor deficiency: In the rare Bardet Biedl syndrome, there is a defect in the assembly of the primary cilium in hypothalamic neurons and, consequently, there is ectopic activation of the MCH-R1 signaling pathway, leading to hyperphagia and a decrease in satiety responsible for obesity and being overweight in affected children [13,14].