UCP1 and obesity due to melanocortin 4 receptor deficiency: A number of independent genetic association studies suggested an association between UCP1 gene variants and obesity, type 2 diabetes mellitus, body fat distribution, and metabolic syndrome-related traits (Clement et al., 1996; Hamann et al., 1998; Kiec-Wilk et al., 2002; Forga et al., 2003; Herrmann et al., 2003; Ramis et al., 2004; Sramkova et al., 2007), while other studies failed to demonstrate such correlations (Urhammer et al., 1997; Fogelholm et al., 1998; Gagnon et al., 1998; Sivenius et al., 2000; Nieters et al., 2002; Malczewska-Malec et al., 2004; Mottagui-Tabar et al., 2008).