C9orf72 and amyotrophic lateral sclerosis: The most common mutations in our group of patients with SOD1 mutations (p.Arg116Gly n = 26, p.Asp91Ala n = 11, and p.Leu145Phe n = 6) are generally associated with a comparatively benign course of disease (Supplementary Table 1) which has to be kept in mind when interpreting the following results.15 Compared to amyotrophic lateral sclerosis patients with SOD1 mutations (n = 84), the median age of onset of C9orf72 mutation carriers was 8.0 (SOD1: 50.0 years, IQR 41.0–58.0) years later (P < 0.001; Fig. 1A).