C9orf72 and amyotrophic lateral sclerosis: For example, in C9orf72 ALS patient iPSC-derived motor neurons, all motor neurons progressively accumulate nuclear envelope invaginations, suggesting that they represent functional structural elements independent of pathology, and there was no difference in the frequency of nuclear invaginations between C9orf72 ALS patient-derived motor neurons and control iPSC-derived motor neurons (Ortega et al., 2020).