Endocrine Abstracts

Whilst bariatric surgery is the most effective therapy for idiopathic morbid obesity in adults, little is known about its effectiveness in patients with monogenic obesity syndromes. We report 5-year outcome of gastric bypass surgery in a young man with severe super-obesity associated with melanocortin four receptor (MC4R) mutation.

A 22-year-old male with a weight of 221.6 kg and BMI 76.7 kg/m² was referred to our centre for bariatric surgery. Previous attempts at lifestyle measures, dieting and treatment with orlistat had been ineffective. His biochemical and haematological profiles and sleep studies were normal. Following multidisciplinary assessment he underwent Roux-en-Y gastric bypass (RYGB) surgery in July 2007 and achieved weight loss of 60 kg in the first postoperative year. He was treated with sibutramine 15 mg daily from 2008 to 2010 to facilitate further weight reduction. He continues to report good post-surgical appetite suppression and to-date has achieved weight reduction of 75.8% of excess weight.

Heterozygous MC4R mutations have been associated with dominantly inherited obesity in various ethnic groups and non-surgical interventions are rarely effective in the long-term. One previous report of bariatric surgery in a patient with complete MC4R deficiency reported poor weight loss after gastric banding. We speculate that patients with MC4R mutations achieve superior weight loss outcomes from procedures such as RYGB that produce neurohormonal changes rather than gastric restriction alone.