LGI1 (leucine-rich, glioma-inactivated 1) mutations are responsible for an inherited focal epileptic syndrome with onset in adolescence. LGI1-related epilepsy mutations result from a loss of function. We have used a strategy of conditional knockout to model the haploinsufficiency observed in the human genetic condition. According to Mendelian ratios, we have obtained LGI1+/- and LGI1-/- mice which are undistinguishable from wild type littermates at birth. At age P10, LGI1-/- mice start to have spontaneous frequent seizures monitored by EEG-video. The complete loss of LGI1 leads to premature death in the null-mutant mice around P15-P18 apparently from seizures. Morphological modifications (mossy fiber sprouting, gliosis, neuronal loss) subsequent to seizures are observed in the hippocampus of the LGI1-/- mice.THIS MODEL IS AVAILABLE THROUGH EMMA