Liraglutide Treatment in a Morbidly Obese Adolescent with a MC4R Gene Variant: Side Effects Reduce Success

Variants of the melanocortin-4 receptor (MC4R) gene are the most common cause of monogenic obesity. It has been shown that, while obesity cannot be controlled with diet and exercise, glucagon-like-peptide-1 receptor agonists (GLP-1 RA) provide weight loss in the short term. In this paper, our experience with liraglutide treatment in an adolescent patient carrying a MC4R gene variant is presented. A female patient was admitted first at the age of 12.5 years with a complaint of progressive weight gain. She had marked excess of appetite since infancy. On physical examination of the pubertal female patient with a body mass index (BMI) of 36.1 kg/m2 (3.48 standard deviation score), there was no pathological finding except diffuse acanthosis nigricans. Laboratory examinations revealed only insulin resistance. Weight loss was not achieved with lifestyle changes, metformin and orlistat treatments. On genetic examination, a sporadic heterozygous c.206T>G(p.I69R) variant that had been reported previously, was found in MC4R gene. Treatment with the GLP-1 RA, liraglutide, was initiated and a 19.2% reduction was achieved in the body weight and BMI at the end of 32 weeks. However, the patient, whose treatment compliance was disrupted due to significant gastrointestinal complaints, returned to her former weight within a few months (13 weeks) after treatment was stopped. In this case with a known pathogenic variant in MC4R gene, decrease of appetite and weight loss were achieved with liraglutide treatment, but side-effects of this treatment led to discontinuation of therapy. In such cases, there is need for effective and tolerable treatment options.