1 Nephrology and Rheumatology, University Medical Center Goettingen, Goettigen, Germany.
2 Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany.
3 Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany.
4 Pediatric Nephrology, Children´s and Adolescents´ Hospital, University Hospital of Cologne, Faculty of Medicine, University of Cologne, Cologne, Germany.