TFAP2A and obesity due to melanocortin 4 receptor deficiency: Recently, it was reported that Drosophila homologs of the human obesity-linked genes TFAP2B and KCTD15 [TfAP-2 and Tiwaz (Twz)] regulate at least two genes involved in the production and secretion of octopamine within the brain, Tyramine β hydroxylase (Tbh) and Vesicular monoamine transporter (Vmat) (Figure 2).