1. The University of the Witwatersrand Donald Gordon Medical Centre, Neurology, Johannesburg, South Africa
2. Division of Human Genetics, National Health Laboratory Service & School of Pathology, The University of the Witwatersrand, Johannesburg, South Africa
3. Department of Neurology, James J. Peters Veterans Affairs Medical Center, Bronx, NY, USA
4. Department of Neurology, Mount Sinai School of Medicine, New York City, NY, USA
5. NHS Borders, United Kingdom; Centre for Clinical Brain Sciences, University of Edinburgh, UK
6. School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
7. Department of Neurology, University of Stellenbosch, Cape Town, South Africa
8. Department of Psychiatry, Division of Neurobiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA