The elevated circulating RBP4 level is also associated with hepatic lipid accumulation and liver steatosis in humans [151,156], The study using the NAFLD model mice further showed that the acceleration of NAFLD in RBP4 transgenic mice was mainly attributed to reduced mitochondrial content and impaired mitochondrial fatty acid β-oxidation [157]. The gene discussed is RBP4; the disease is fatty liver disease.