C9 and amyotrophic lateral sclerosis: We selected a gender mix of five different ALS patients with confirmed heterozygous HREs in intron 1 of the C9ORF72 gene locus with repeat numbers between 50 and 1,800 (C9-1, C9-2, C9-3, C9-4, and C9; Table 2), respectively, and compared them against three healthy control donors (Ctrl1, Ctrl2, and Ctrl3; Table 2).