SLC6A3 and obesity due to melanocortin 4 receptor deficiency: Among individuals with the DRD2/ANKK1 haplotype (T-C-T-A) previously associated with obesity [25], no marked increase in effect of the SLC6A3 VNTR on obesity was observed (** = reference; OR*9 = 0.89, 95% CI 0.54–1.46; OR99 = 0.54, 95% CI 0.23–1.33, p-value for interaction = 0.62).