UCP2 and obesity due to melanocortin 4 receptor deficiency: Moreover, in NASH patients and ob/ob mice, the expression of the uncoupling protein-2 (UCP-2) elevated, which aggravated the mitochondrial uncoupling and proton leakage of liver mitochondria, and reduced the efficiency of liver ATP synthesis (Chavin et al., 1999; Serviddio et al., 2008), All this leads to impaired ATP synthesis which has been validated in obesity and NAFLD patients.