Although heterozygous expression of the KCNT1-Y796H variant is sufficient to cause severe childhood epilepsy in humans, we only observed rare behavioral seizures in heterozygous Kcnt1Y777H mice see Discussion (Shore et al., 2020); however, we identified hyperexcitable, hypersynchronous cortical networks and frequent, early-onset seizures in homozygous Kcnt1Y777H mice. Here, KCNT1 is linked to epilepsy.