C9orf72 and amyotrophic lateral sclerosis: Overall, we report intrinsic properties of C9orf72 ALS/FTD iPSC-MG mono-cultures and set the stage for the use of this human endogenous disease model in co-cultures with C9orf72 ALS/FTD iPSC derived neurons and other glial cells, astrocytes, and/or oligodendrocytes.