Novel Gain of Function Mouse Model of KCNT1-Related Epilepsy

KCNT1-related epilepsy is an autosomal dominant neurodevelopmental disorder with at least 64 known human variants, each with unique electrophysiological and epileptic characteristics. A multi-disciplinary collaboration generated a novel mouse model (C57BL/6-Kcnt1em1Bryd) carrying the G269S variant, corresponding to human G288S, located within the coding region of the channel pore. Network excitability of cultured cortical neurons from Kcnt1+/G269S exhibited sustained hyperexcitability and hypersynchronous bursting while Kcnt1G269S/G269S neurons showed early excessive bursting followed by network collapse, suggesting excitotoxicity. Kcnt1+/G269S displayed poor motor coordination, erratic breathing, and increased apneas. Critically, Kcnt1+/G269S were more susceptible to thermal-induced seizures in early life. In summary, these data: (i) provide a novel mouse model of KCNT1-related epilepsy, (ii) provide strong in vitro evidence of neuronal hyperexcitability, (iii) illustrate early-life seizures as a functional outcome measure, and (iv) lay the groundwork for future analysis of neural activity in vivo and modeling circuit level dynamics in vitro and in silico. Significance Statement Gain-of-function mutations in the sodium-gated potassium channel KCNT1 have been linked to pediatric epilepsy of varying severity. The human KCNT1 variant G288S (G269S in mice) is linked to Autosomal Dominant Nocturnal Frontal Lobe Epilepsy (ADNFLE), Epilepsy of Infancy with Migrating Focal Seizures (EIMFS), and other severe developmental epileptic encephalopathies. There are currently no therapeutics to prevent the progression of KCNT1-related epilepsy, therefore, the scientific community requires a novel mouse model that is well characterized, in vitro and in vivo, to screen and assess targeted therapeutics. Herein, we engineered a novel mouse to assess developmental and adult phenotypes resulting from the G288S/G269S variant, in vitro and in vivo, to advance translation toward therapeutic testing for individuals with KCNT1-related epilepsy.