1 Division of Pediatric Surgery, Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
2 Pediatric Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
3 Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
4 Anorectal Physiology Laboratory, Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
5 Division of Pediatric Surgery, Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Anorectal Physiology Laboratory, Department of Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.