UCP1 and obesity due to melanocortin 4 receptor deficiency: Although studies carried out in humans suggested that UCP1 gene polymorphisms are associated with the obesity pathogenesis and with the disequilibrium of lipid metabolism [26,27,28,29,30], these insights are not confirmed in other studies carried out on humans [31,32,33], as well as by the findings obtained in the current study, which showed no correlation between the values of UCP1 and the levels of HDLs and LDLs in investigated horses.