1. ; Institute for Genetic Medicine; University of California; Los Angeles California USA
2. ; Departments of Physiological Science and Neurology, and the Brain Research and Molecular Biology Institutes; University of California; Los Angeles California USA
3. ; Department of Pediatric Neurology, Academic Hospital; Free University; Brussels Belgium
4. ; Department of Pediatrics; Catholic University of Leuven; Belgium
5. ; Departments of Clinical Chemistry and Pediatrics, Academic Hospital; Free University of Amsterdam; The Netherlands
6. ; Department of Pediatrics; University of California; San Diego, La Jolla California USA
7. ; Department of Molecular and Medical Genetics, Biochemical Genetics Laboratory; Oregon Health Sciences University; Portland Oregon USA