CHI3L1 and viral encephalitis: As shown in Figure 1A, the levels of YKL-40 in the CSF of anti-NMDAR encephalitis patients at the onset of disease (median 128.3 pg/mL; interquartile range 97–171.4 pg/mL) were significantly higher than those of VM patients (94.7 pg/mL; 77.1–113.6 pg/mL) and controls (82.4 pg/mL; 67.35–93.35 pg/mL) (p = 0.017, p < 0.001, respectively).