1 Seattle Children's Research Institute, Center for Clinical and Translational Research, Seattle, Washington, USA; Department of Pediatrics, Division of Hematology/Oncology, University of Washington School of Medicine, Seattle, Washington, USA; Department of Pediatrics, Division of Bioethics & Palliative Care, University of Washington School of Medicine, Seattle, Washington, USA. Electronic address: abby.rosenberg@seattlechildrens.org.