1. Department of Neurology; Mayo Clinic; 200 First Street, SW Rochester Minnesota 55905 USA
2. Department of Neurology; China-Japan Friendship Hospital; Beijing China
3. Biomedical Statistics and Informatics; Mayo Clinic, Rochester; Minnesota USA
4. Department of Laboratory Medicine and Pathology; Mayo Clinic, Rochester; Minnesota USA
5. Department of Medical Genetics; Mayo Clinic, Rochester; Minnesota USA