Consistent with the results of the clinical trial, longitudinal analysis of the samples obtained from patients who received one vs. two standard courses of IVIg showed that the second course of treatment did not prevent a further rise in serum NfL, which likely further indicates that a continuous process of axonal degeneration occurs in GBS, despite treatment with IVIg. The gene discussed is NEFL; the disease is Guillain-Barre syndrome.