1. Division of Neurology; The Children's Hospital of Philadelphia; Philadelphia Pennsylvania U.S.A
2. Department of Neuropediatrics; University Medical Center Schleswig-Holstein; Christian-Albrechts-University; Kiel Germany
3. Institute for Genomic Medicine and Department of Pathology and Cell Biology; Columbia University Medical Center; New York New York U.S.A
4. Division of Genetic Medicine; Department of Pediatrics; University of Washington; Seattle Washington U.S.A