Analysis of the proportions of ISLET1-positive neurons derived from each control and each mutant ALS iPSC clone at T0 (in young or “just born” MNs, yMNs) showed no significant difference between control and ALS clones (Fig. 1e) (all controls (including SOD1-ISO and TARDBP-ISO): 79.1 ± 1.6%; SOD1: 73.5 ± 2.3%; C9orf72: 84.8 ± 1.6%; TARDBP: 83.2 ± 4.3% (mean ± SEM)). The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.