In order to assess whether the increased Gpr55 expression of F1.Scn1a+/- mice contributes to the Dravet syndrome phenotype, we generated F1.Scn1a+/- mice with heterozygous deletion of Gpr55 (F1.Scn1a+/;Gpr55+/-). The gene discussed is GPR55; the disease is encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.