1. Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa
2. Centre for Statistical Consultation, Stellenbosch University, Stellenbosch, South Africa
3. Department of Psychiatry and Neuroscience Institute, University of Cape Town, Cape Town, South Africa
4. Department of Psychology, Stellenbosch University, Stellenbosch, South Africa
5. SAMRC Genomics of Brain Disorders Research Unit, Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa