To evaluate the role of astrocytes in ALS, we differentiated hiPSCs from two ALS-patients with FUS mutations (R521H and P525L) and their corresponding CRISPR-Cas9 gene-edited isogenic controls (R521R and P525P) [25, 27, 28] into astrocytes using a slightly modified version of a recently published protocol [29]. The gene discussed is FUS; the disease is amyotrophic lateral sclerosis.