Our pilot GWAS reported that two genes, mitogen-activated protein kinase, kinase 6 (MAP2K6) and DnaJ Heat shock Protein Family Member C6 (DNAJC6), were distinguishingly related to both the resting metabolic rate (RMR) and body mass index (BMI) as biomarkers of obesity in children. Here, MAP2K6 is linked to obesity due to melanocortin 4 receptor deficiency.