1. Department of Physical Medicine and Rehabilitation; School of Medicine; University of California; Davis; 4860 Y Street; Suite 3850; Sacramento; California; 95817; USA
2. Center for Genetic Medicine Research, Children's National Medical Center; Washington; DC; USA
3. Department of Neurology, Kennedy Krieger Institute; Baltimore; Maryland; USA
4. Department of Neurology, Washington University; St. Louis; Missouri; USA
5. Department of Neurology, University of Pittsburgh and Department of Veterans Affairs Medical Center; Pittsburgh; Pennsylvania; USA