Among Abs and ICs, Nf‐H Abs revealed the best performance in distinguishing ALS from HC (ABC; Fig. 3D, AUC = 0.72, respectively, p = 0.0001), while plasma Nf‐L ICs discriminated C9+ve from HC (Fig. 3F, AUC = 0.78, p < 0.0001) and ALS‐F from HC (Fig. 3E, AUC = 0.72; p < 0.0001). This evidence concerns the gene C9 and amyotrophic lateral sclerosis.