The change of IL-6 as a dependent variable was affected by IL-12, dopamine, and leptin as independent or predictor variables, and the change of leptin as a marker of obesity was greatly affected by both pro-inflammatory cytokines (IL-6 and IL-12, serotonin, and body weight (Table 4). This evidence concerns the gene IL6 and obesity due to melanocortin 4 receptor deficiency.