In order to explore whether altered Ca2+ homeostasis and ER stress are cellular phenotypes associated with C9orf72‐related ALS/FTD, we generated iPSC lines from skin fibroblasts from patients carrying C9orf72 hexanucleotide expansions and differentiated them to MNs and cortical neurons (CNs). Here, C9orf72 is linked to frontotemporal dementia.