C9 and amyotrophic lateral sclerosis: We found a significant upregulation of Nf‐L ICs in T2 and T3 compared to T1 (p = 0.0259) and the same trend of increase (close to statistical significance) for Nf‐L ICs and Nf‐H Abs in C9+ve ALS and in ALS‐F, respectively (Fig. 5A).