1Hospital for Children and Adolescents and Haartman Institute, Transplantation Laboratory, University of Helsinki, Helsinki, Finland, , FI
2National Public Health Institute, Helsinki, Finland, , FI
3Steno Diabetes Center, Gentofte, Denmark, , DK
4Medical School, University of Tampere and Department of Paediatrics, Tampere University Hospital, Tampere, Finland, , FI