The CXCL12 rs501120 C allele and the FTO rs9939609 A allele were risk factors (rs501120: OR = 1.96, p = 0.02; rs9939609: OR = 2.2, p = 0.04), while LEP rs7799039 was a protective factor (rs7799039: OR = 0.6, p = 0.03) in the obesity group. This evidence concerns the gene CXCL12 and obesity due to melanocortin 4 receptor deficiency.