Affiliation: | (1) Medical Neurology Branch, National Institute of Neurological and Communicative Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA;(2) Present address: Center for Neuromuscular Diseases, Dept. of Neurology, Univ. of Southern California School of Medicine, 616 S Witmer Street, 90017 Los Angeles, CA, USA |