1. Department of Rheumatology, Charlotte Maxeke Johannesburg Academic Hospital, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, Johannesburg, South Africa
2. Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, P.O. Box 1012, Melville 2109, Johannesburg, South Africa