In contrast, the rare cases of monogenic forms of obesity, are mainly caused by biallelic mutations in a single gene, usually in the leptin-melanocortin satiety pathway, and are characterized by vary severe, early-onset obesity, usually with evident hyperphagia, and in some cases associated to other metabolic comorbidities and influencing growth pattern even in the first years of life (Handakas et al., 2022). The gene discussed is LEP; the disease is Obesity.