GRIA2 and epilepsy: In addition, heterozygous GluA2ΔECS mice, in which the Q/R editing of GluA2 is abolished due to a mutation in the editing-determining exon complementary sequence (ECS), die at P20 and show an early onset of epilepsy like ADAR2−/− mice (Brusa et al., 1995; Feldmeyer et al., 1999).