1. Department of Neurology, Mayo Clinic , Rochester, MN 55905 , USA
2. Center for Multiple Sclerosis and Autoimmune Neurology, Mayo Clinic , Rochester, MN 55905 , USA
3. Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, MN 55905 , USA
4. Department of Immunology, Mayo Clinic , Rochester, MN 55905 , USA