Jaques Van Heerden1,2, Mariana Kruger1. 1. Paediatric Haematology and Oncology, Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg Hospital, Cape Town, South Africa. 2. Paediatric Haematology and Oncology, Department of Paediatrics, Antwerp University Hospital, Antwerp, Belgium.