The NfL ratio was lower in GBS patients (median [IQR] 30.8 [15.6–65]) compared with HC (42.4 [ 33.3–55.5]), active MS (49.2 [ 27.9–96.9]), non-active MS (38.9 [23.1–71.3]) and ALS (69.4 [52.2–113]), p < 0.0001 (Fig. 5a). Here, NEFL is linked to Guillain-Barre syndrome.