GFAP and Down syndrome: Compared with the nonoverlapping syndrome group, the GFAP-MOG group exhibited a higher frequency of ON (71.4% vs. 4.6%, p < 0.001) and seizures (57.1% vs. 15.4%, p = 0.032), more cortical lesions (85.7% vs. 35.4%, p = 0.003), lower CSF white blood cell counts (median: 22 cells/mm3 vs. 94 cells/mm3, p = 0.020) and protein levels (median: 0.381 g/L vs. 0.78 g/L, p = 0.004), and a greater proportion of patients receiving long-term immunotherapy (57.1% vs. 13.8%, p = 0.021) (Table 3).