1 Center for Congenital Heart Diseases, Dept of Pediatric Cardiology, Beatrix Children's Hospital, National Referral Center for Pediatric Pulmonary Hypertension, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
2 Dept of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
3 Center for Congenital Heart Diseases, Dept of Pediatric Cardiology, Beatrix Children's Hospital, National Referral Center for Pediatric Pulmonary Hypertension, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands r.m.f.berger@umcg.nl.