The observation that Pcyox1 deficiency in Apoe−/− mice fed with HFD, a model of obesity-accelerated atherosclerosis accompanied by development of a metabolic syndrome phenotype [19], have less adipose tissue depots, led us to further investigate the role of PCYOX1 in adipogenesis. This evidence concerns the gene PCYOX1 and obesity due to melanocortin 4 receptor deficiency.