Mice with experimental autoimmune encephalomyelitis (EAE), the most commonly used preclinical murine model of MS, also show a marked reduction in serum concentrations of met-enkephalin compared with baseline levels and with controls prior to the onset of clinical behavioral signs of disease (Ludwig et al., 2017; Patel et al., 2020). The gene discussed is MET; the disease is myeloid sarcoma.