1. Department of Human Genetics Yokohama City University Graduate School of Medicine Yokohama 236‐0004 Japan
2. Department of Biochemistry Hamamatsu University School of Medicine Hamamatsu 431‐3192 Japan
3. Department of Functional Neurosurgery Epilepsy Center Nishi‐Niigata Chuo National Hospital Niigata 950‐2085 Japan
4. Department of Child Neurology Nishi‐Niigata Chuo National Hospital Niigata 950‐2085 Japan
5. Department of Pediatrics Showa University School of Medicine Tokyo 142‐8666 Japan
6. Clinical Research Institute Kanagawa Children's Medical Center Yokohama 232‐8555 Japan