1. Clinical Epidemiology Research Unit of Hospital Infantil de México Federico Gómez|Faculty of Medicine of Universidad Nacional Autónoma de México, Mexico City 06720, Mexico
2. Department of Hemato-Oncology of Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico
3. Clinical Epidemiology Research Unit of Hospital Infantil de México Federico Gómez|Faculty of Chemistry of Universidad Nacional Autónoma de México, Mexico City 06720, Mexico
4. Clinical Epidemiology Research Unit of Hospital Infantil de México Federico Gómez, Mexico City 06720, Mexico