RPTOR and obesity due to melanocortin 4 receptor deficiency: Among the genes associated with adipose tissue formation, metabolism, and obesity during childhood, Heitkamp et al. showed that children/adolescents homozygous for the G allele in the rs12940622 polymorphism of the regulatory-associated protein of MTOR (RPTOR; OMIM * 607130) gene are resistant to weight loss compared to homozygous non-carriers in a 4–6-week obesity intervention program [55].