Here, we deleted the mTOR pathway inhibitor Pten from a subset of excitatory hippocampal granule cells, modeling the mosaic loss of mTOR regulators now identified in focal cortical dysplasia Type II (FCDII), tuberous sclerosis complex, and numerous other conditions associated with epilepsy (Girodengo et al., 2022). The gene discussed is PTEN; the disease is epilepsy.