MC4R and obesity due to melanocortin 4 receptor deficiency: On one hand, pediatric patients with obesity and MC4R mutations other than Ile269Asn showed weight loss in response to a controlled and intensive program of restricted dieting and daily physical activity [10], while weight loss was not achieved in an independent study of European children and adolescent MC4R mutation carriers in response to a less intensive dietary program, suggesting the need for personalized treatment based on MC4R genotype [11].