(1) liver fat may activate microglial cells in the brain by inducing inflammation, and thus resulting in elevated expression of inflammatory cytokines (49); (2) similar with obesity, patients with NAFLD may also increase brain insulin resistance, thereby causing oxidative stress, excessive free fatty acids, and brain mitochondrial disorders (50); (3) impaired liver function can cause insufficient detoxification and allows neurotoxins to enter the cerebral circulation, which can increase permeability of blood–brain barrier and neuroinflammation (51, 52). The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.