Using bivariate logistic regression analysis and age as a covariate to account for age-related effects (Fig. 3b), we found a slight but statistically significant increase in TBR1 methylation for the obesity subgroup (31.6% mean methylation) in comparison to the normal weight group (30.1% mean methylation) exhibiting only TBR1 methylation but not age as a significant variable (P = 0.019, OR = 1.11, 95%CI 1.02–1.20) in the bivariate regression model. This evidence concerns the gene TBR1 and obesity due to melanocortin 4 receptor deficiency.