Blackwell Acta Medica Okayama 0013-9580 49 3 2007 Rasmussen encephalitis associated with SCN1A mutation 521 526 EN Iori Ohmori Departments of Cellular Physiology, Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama University Mamoru Ouchida Departments of Molecular Genetics, Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama University Katsuhiro Kobayashi Departments of Child Neurology, Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama University Yoshimi Jitsumori Takushi Inoue Departments of Child Neurology, Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama University Kenji Shimizu Departments of Molecular Genetics, Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama University Hideki Matsui Departments of Cellular Physiology, Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama University Yoko Ohtsuka Departments of Child Neurology, Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama University Yoshihiro Maegaki Division of Child Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University Mutations in the SCN 1 A gene, encoding the neuronal voltage-gated sodium channel alpha1 subunit, cause SMEI, GEFS+, and related epileptic syndromes. We herein report the R1575C-SCN 1 A mutation identified in a patient with Rasmussen encephalitis. R1575C were constructed in a recombinant human SCN 1 A and then heterologously expressed in HEK293 cells along with the human beta1 and beta2 sodium channel accessory subunits. Whole-cell patch-clamp recording was used to define biophysical properties. The R1575C channels exhibited increased channel availability and an increased persistent sodium current in comparison to the wild-type. These defects of electrophysiological properties can result in neuronal hyperexitability. The seizure susceptibility allele may influence the pathogenesis of Rasmussen encephalitis in this case. No potential conflict of interest relevant to this article was reported.