1. Division of Human Genetics, Department of Pathology; Faculty of Health Sciences University of Cape Town; Cape Town South Africa
2. Department of Otolaryngology; Molecular Otolaryngology and Renal Research Laboratories, The University of Iowa; Iowa City IA USA
3. Department of Medicine; Faculty of Health Sciences University of Cape Town; Cape Town South Africa
4. Center for Statistical Genetics, Department of Molecular and Human Genetics; Baylor College of Medicine; Houston TX USA