Until now, polymorphisms such as Pro12Ala, C1431T (both in PPAR-γ2), and Trp64Arg (β3-AR) were mainly associated with metabolic disorders, while FAM13A gene variants (rs1903003, rs7671167, rs2869967) were more prevalent in COPD [25,54,55]. Here, PPARG is linked to metabolic disease.