Canals et al. report a new disease model of Frontotemporal Dementia generated with genome editing of the CHMP2B gene in human embryonic stem cells, differentiated to induced neurons and astrocytes, and generating neuron-astrocyte co-cultures to identify impaired astrocytic glutamate homeostasis and evident alterations in neuronal network connectivity and synchronization. Here, CHMP2B is linked to frontotemporal dementia.