Weight loss after bariatric surgery in morbidly obese adolescents with MC4R mutations.

Objective: To determine the frequency of Melanocortin 4 Receptor (MC4R) mutations in morbidly obese adolescents undergoing bariatric surgery and compare weight loss outcomes in patients with and without mutations.

Design And Methods: In this prospective cohort study, 135 adolescent patients evaluated for bariatric surgery were screened for MC4R mutations; 56 had 12-month postoperative data available for analysis.

Results: MC4R mutations were detected in five of the 135 patients (3.7%); four underwent restrictive bariatric surgery. For the three patients with gastric banding, percent excess weight loss (%EWL) postoperatively was 36.0% at 5 years in one, 47% at 4 years in the second, and 85% at 1 year in the third. For the patient with gastric sleeve resection, %EWL of 96% was attained at 1 year postoperatively. The four MC4R cases had a higher, although nonsignificant, %EWL compared to 52 nonmatched controls at 12 months postoperatively (48.6% vs. 23.4%; P < 0.37). When matched by age, sex, and race to 14 controls, there was no significant difference in %EWL (P < 0.31), BMI change (P < 0.27), or absolute weight loss (P < 0.20).

Conclusion: The frequency of MC4R mutations is similar to prior studies, with affected patients showing beneficial weight loss outcomes.