PDK4 and obesity due to melanocortin 4 receptor deficiency: First, we identified gene sets related to the function of each obesity-related serum factor: HG/HI (Insr, Irs1, Rps6kb1, Slc2a4, Slc2a5, Slc2a1), TNF-α (Tnfrsf1a, Tradd, Traf2, Fadd), IL-6 (Il6ra, Il6st, Jak1), and fatty acids (PA, LA, Chol; Ffar1, Ffar4, Ppara, Pdk4, Pgc1a).