Funder: Kay Kendall Leukaemia Fund

Funder: This work was supported by the Swedish Childhood Cancer Fund (PDS13/001, to PJ), the Swedish Research Council (2014-06807, to PJ), a Specialist Programme from Bloodwise (12048, to AJW), the UK Medical Research Council (MR/T012412/1, to AJW), European Cooperation in Science and Technology (COST) Action CA18233, “European Network for Innovative Diagnosis and treatment of Chronic Neutropenias, EuNet INNOCHRON” (to AJW), a Wellcome Trust strategic award to the Cambridge Institute for Medical Research (100140, to AJW), a core support grant from the Wellcome Trust and MRC to the Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, the Connor Wright Project, Ted’s Gang and the Cambridge National Institute for Health Research Biomedical Research Centre (BRC-1215-20014). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. A Wellcome Intermediate Fellowship (105914/Z/14/Z) and the Kay Kendall Leukaemia Fund (to CCW). We thank Dr. D. Y. Chirgadze for assistance with data collection at the Cryo-EM Facility, Department of Biochemistry, University of Cambridge, funded by the Wellcome Trust (206171/Z/17/Z; 202905/Z/16/Z), the Departments of Biochemistry and Chemistry, the Schools of Biological Sciences and Clinical Medicine and the University of Cambridge. We acknowledge Diamond Light Source for access and support of the cryo-EM facilities at the UK’s national Electron Bio-imaging Centre (eBIC) [under proposal EM BI22238], funded by the Wellcome Trust, MRC and BBRSC.