Treatment options for children with monogenic forms of obesity

Mutations in genes involved in energy balance regulation within the central nervous system lead to monogenic forms of obesities. Individuals with these mutations are characterized by early-onset obesity and in some cases by endocrine abnormalities. Carriers of leptin gene mutations are able to normalize their body weight after daily subcutaneous leptin administration. Pharmacotherapy targeting the specific-gene deficiencies has not clinically been tested in other monogenic obesities. Mutations in the melanocortin 4 receptor gene (MC4R) represent the most common monogenic cause of human obesity. Several treatment options have been investigated in subjects with MC4R mutations. Few studies showed that an intensive life-style intervention induces similar weight reduction in MC4R mutation carriers in comparison to MC4R mutation noncarriers. However, long-term body weight maintenance is hardly ever achieved in MC4R mutation carriers. Sibutramine, serotonin and noradrenalin reuptake inhibitor, in MC4R mutation carriers induced weight reduction and improved cardiometabolic health risks. This result was also found in our homozygous MC4R mutation carrier. In vitro studies of melanocortin agonists efficiently activate mutated MC4R with impaired endogenous agonist functional response and thus, further research in the development of drugs for MC4R mutations is needed. An administration of intranasal adrenocorticotropic hormone was not shown to be effective in subjects with pro-opiomelanocortin gene mutations. Bariatric surgery has also been performed in few of MC4R mutation carriers. After gastric banding, lower body weight reduction and worse improvement of metabolic complications was found in MC4R mutation carriers versus noncarriers. However, preliminary results suggest that diversionary operations as gastric bypass represent a suitable method also for MC4R mutation carriers. In conclusion, the management of monogenic obesities still remains a challenge.