Our study showed that the underweight category had the highest concentration, with 465.10 pg/mL, followed by the normal-weight control, with a mean BDNF concentration of 417.12 pg/mL, and the overweight and obesity classes I, II, and III, with BDNF protein concentrations of 282.2 pg/mL, 247.9 pg/mL, 186.3 pg/mL, and 178.6 pg/mL, respectively (Figure 1). The gene discussed is BDNF; the disease is obesity due to melanocortin 4 receptor deficiency.