Lipid partitioning (i.e., the distribution of fat among its potential depots) is much more related to the metabolic phenotype of obese children and adolescents than the degree of obesity.10 Thus, lipid partitioning is a major determinant of peripheral insulin sensitivity and is strongly associated with other metabolic biomarkers such as systemic inflammation and free fatty acid fluxes. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.