This review covers the main Ucp SNPs A–3826G, A–1766G, A–112C, Met229Leu, Ala64Thr (Ucp1), Ala55Val, G–866A (Ucp2), and C–55 T (Ucp3), which may be associated with the development of obesity, disturbance in lipid metabolism, T2D, and cardiovascular diseases. The gene discussed is UCP3; the disease is obesity due to melanocortin 4 receptor deficiency.