[1] Unidad Nacl Oncol Pediat, Guatemala City, Guatemala
[2] Univ Milano Bicocca, Dept Clin Med & Prevent, Monza, Italy
[3] Univ Milano Bicocca, Dept Pediat, Monza, Italy
[4] Hosp Sick Children, Toronto, ON M5G 1X8, Canada
[5] Univ Toronto, Toronto, ON, Canada
[6] McMaster Univ, Dept Pediat, Hamilton, ON L8S 4J9, Canada
[7] McMaster Univ, Dept Pathol, Hamilton, ON L8S 4J9, Canada
[8] McMaster Univ, Dept Med, Hamilton, ON L8S 4J9, Canada