1. The University of the Witwatersrand Donald Gordon Medical CentreNeurology Johannesburg South Africa
2. Division of Human GeneticsNational Health Laboratory Service and School of Pathology, Faculty of Health Sciences, The University of the Witwatersrand Johannesburg South Africa
3. Department of PsychologySchool of Human and Community Development, University of the Witwatersrand. Johannesburg South Africa
4. UCL Huntington's Disease CentreUniversity College London UK
5. Clinical Pharmacology UnitInstituto de Medicina Molecular Portugal
6. Laboratory of Clinical Pharmacology and TherapeuticsUniversity of Lisbon Portugal
7. German Center for Neurodegenerative Diseases (DZNE) Bonn Germany
8. Division of Neurology, Department of MedicineUniversity of Stellenbosch Cape Town South Africa
9. Departments of Psychiatry and Neurology, Program in Cellular and Molecular MedicineJohns Hopkins University School of Medicine Baltimore MD USA