Post-hoc analysis revealed that myostatin protein content was significantly increased in myotubes treated with serum from NAFLD (42%, p = 0.05, d = 2.5) and ESLD (44%, p = 0.04, d = 3.6) compared with those treated with serum from CON. The gene discussed is MSTN; the disease is metabolic dysfunction-associated steatotic liver disease.