Furthermore, although overall support has been gained for the hypothesis that inherited variations in CART could influence the development of obesity, such genetic linkage was absent for some other sequence variants detected within the gene, where the polymorphisms have been speculated as insufficient to disturb the peptide structure or create topological and conformational changes in the protein that would ultimately affect the functional activity of the peptide (Echwald et al., 1999; Walder et al., 2000; Rogge et al., 2008). This evidence concerns the gene CARTPT and obesity due to melanocortin 4 receptor deficiency.