A group effect (p = 0.011) and pairwise comparisons showed IL‐6 concentrations in children with PWS and children with obesity were greater than concentrations in children without obesity (0.94 ± 0.12 pg/mL and 0.95 ± 0.10 pg/mL vs. 0.52 ± 0.11 pg/mL; p = 0.038 and p = 0.020, respectively). This evidence concerns the gene IL6 and obesity due to melanocortin 4 receptor deficiency.