Since FGF21 show a strong association with obesity, we categorized the study participants into non-obese (BMI < 25 kg/m2) and obese (BMI ≥ 25 kg/m2) groups and assessed the association between FGF21 levels and each parameter in both groups (Supplementary Table S1 online and Table 4). This evidence concerns the gene FGF21 and obesity due to melanocortin 4 receptor deficiency.