C9orf72 and amyotrophic lateral sclerosis: The time windows where the MMN shows a statistically significant decrease in the combined ALS patient cohort compared to controls was 99–173 ms (Mann–Whitney U test, p < 0.05, n1 = 19, n2 = 89) (Figure 4), with the most prominent difference between patients and controls in the spinal and C9ORF72-negative sub-cohorts (Figure 5).