In line with this finding, the ALS/FTD‐derived MNs also showed significantly increased staining with PI in up to 32% of C9orf72 MNs compared to healthy MNs, indicating reduced survival compared to control MNs (p < .01, one‐way ANOVA) (Fig. 5C). This evidence concerns the gene C9orf72 and amyotrophic lateral sclerosis.