C9orf72 and frontotemporal dementia: To determine if C9orf72 ALS/FTD iPSC-MG can phagocytose synapses or exhibit altered phagocytosis due to the presence of C9orf72 HRE, we exposed iPSC-MG mono-cultures to synaptoneurosomes (hSN) derived from healthy control human brain and assessed synaptoneurosomes engulfment via live confocal microscopy.