A novel LGI1 mutation causing autosomal dominant lateral temporal lobe epilepsy confirmed by a precise knock‐in mouse model

AIMS: This study aimed to explore the pathomechanism of a mutation on the leucine‐rich glioma inactivated 1 gene (LGI1) identified in a family having autosomal dominant lateral temporal lobe epilepsy (ADLTE), using a precise knock‐in mouse model. METHODS AND RESULTS: A novel LGI1 mutation, c.152A>G; p. Asp51Gly, was identified by whole exome sequencing in a Chinese family with ADLTE. The pathomechanism of the mutation was explored by generating Lgi1(D51G) knock‐in mice that precisely phenocopied the epileptic symptoms of human patients. The Lgi1(D51G) (/) (D51G) mice showed spontaneous recurrent generalized seizures and premature death. The Lgi1(D51G) (/+) mice had partial epilepsy, with half of them displaying epileptiform discharges on electroencephalography. They also showed enhanced sensitivity to the convulsant agent pentylenetetrazole. Mechanistically, the secretion of Lgi1 was impaired in the brain of the D51G knock‐in mice and the protein level was drastically reduced. Moreover, the antiepileptic drugs, carbamazepine, oxcarbazepine, and sodium valproate, could prolong the survival time of Lgi1(D51G) (/) (D51G) mice, and oxcarbazepine appeared to be the most effective. CONCLUSIONS: We identified a novel epilepsy‐causing mutation of LGI1 in humans. The Lgi1(D51G) (/+) mouse model, precisely phenocopying epileptic symptoms of human patients, could be a useful tool in future studies on the pathogenesis and potential therapies for epilepsy.