1. Division of Human Genetics, Department of Pathology, University of Cape Town, Observatory 7925, South Africa
2. African Institute for Mathematical Sciences, Muizenberg, Cape Town 7945, South Africa
3. Faculty of Sciences, University of Kinshasa, Kinshasa, Democratic Republic of Congo
4. School of Medical Sciences, University of Cape Coast, PMB, Cape Coast, Ghana
5. Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, PO Box LG 581, Legon, Ghana