Lipoprotein lipase (LPL), fibronectin type III domain containing protein 5 (FNDC5—precursor of irisin), and peroxisome proliferator-activated receptor gamma (PPARγ) are well-known candidate genes since the key roles of their products in lipid and energy metabolism and/or their involvement in the pathogenesis of various complications of dyslipidemia has been extensively documented [6–9]. This evidence concerns the gene FNDC5 and metabolic syndrome.