Ma et al. [33] have found that the expression of irisin in the liver tissue of patients with NAFLD (56 cases with nonalcoholic simple fatty liver and 75 cases with nonalcoholic steatohepatitis) was higher when compared to that in the healthy control group (1.11 ± 0.63 and 1.17 ± 0.61 vs. 0.58 ± 0.39, respectively; P < 0.05). Here, FNDC5 is linked to metabolic dysfunction-associated steatohepatitis.