Obesity is a major public health concern; despite evidence of high heritability, the genetic causes of
obesity remain unclear. In this study, we assessed the presence of mutations in three genes involved in the hypothalamic
leptin-
melanocortin regulation pathway (
leptin, LEP;
leptin receptor, LEPR; and
melanocortin-4 receptor, MC4R), which is important for energy homeostasis in the body, in a group of patients with
severe obesity. For this study, we selected 77 patients who had undergone
bariatric surgery and had a pre-operative body mass index (BMI) >35 kg/m2, early onset and a family history of being
overweight. Candidate genes were screened by direct sequence analysis to search for rare genetic variations. The common LEP -2548 G/A polymorphism was also evaluated for its influence on the BMI (in
obesity patients) and for
obesity risk, using a case-control study involving 117 healthy individuals. Two different non-synonymous alterations in MC4R were found in two patients: the p.(Thr112Met), previously described in the literature as a probable gene involved in the
obesity phenotype, and the novel p.(Tyr302Asp) variant, predicted to be pathogenic by in silico evaluations and family segregation studies. The LEP -2548 G/A polymorphism was not associated with the BMI or
obesity risk. In conclusion, we have reported a novel mutation in MC4R in a family of Italian patients with
severe obesity. Screening for MC4R could be important for directing the carriers of mutations towards
therapy including partial agonists of the MC4R that could normalize their appetite and inhibit
compulsive eating. Next-generation sequencing could be used to clarify the genetic basis of
obesity in the future.