Other ALS studies have also shown neuroprotective deficits in SOD1 mutant hiPSC-astrocytes (Tyzack et al. 2017) and deleterious effects of conditioned media from C9orf72 mutant hiPSC-astrocytes on neurons (Birger et al. 2019). This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.