[1] Univ Alberta, Edmonton, AB, Canada
[2] Netherlands Canc Inst, Amsterdam, Netherlands
[3] Univ Nebraska, Omaha, NE 68182 USA
[4] Childrens Natl Med Ctr, Washington, DC 20010 USA
[5] Univ Hosp Children, Homburg, Germany
[6] UCL, Inst Child Hlth, London, England
[7] Great Ormond St Hosp Sick Children, London, England