1 Department of Paediatrics, Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione-University of Pittsburgh Medical Center, Palermo, Italy.
2 Department of Oncology, Birmingham Women's and Children's National Health Service Foundation Trust, Birmingham, United Kingdom.
3 Department of Surgery and Urology for Children and Adolescents, Medical University of Gdansk, Gdansk, Poland.