1. Roche Diagnostics GmbH Penzberg Germany
2. Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology The Sahlgrenska Academy at University of Gothenburg Mölndal Sweden
3. UCL Institute of Neurology London UK
4. Clinical Chemistry VU University Medical Center Amsterdam The Netherlands
5. Washington University School of Medicine St. Louis MO USA
6. Covance Central Laboratory Services Indianapolis IN USA