FAS and obesity due to melanocortin 4 receptor deficiency: Today, a piece of considerable evidence indicated an alteration in the gene expression of the main lipogenic enzymes; fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) which are associated with adipocyte lipid accumulation in obesity, although with contradictory findings [10, 17, 18]. For instance, Ranganathan G et al.