Acknowledgements: This research was made possible through access to the data and findings generated by the 100 000 Genomes Project. The 100 000 Genomes Project is managed by Genomics England Limited (a wholly owned company of the Department of Health and Social Care). The 100 000 Genomes Project is funded by the National Institute for Health Research and NHS England. The Wellcome Trust, Cancer Research UK, and the Medical Research Council have also funded research infrastructure. The 100 000 Genomes Project uses data provided by patients and collected by the National Health Service as part of their care and support. TSJ is grateful for funding from Great Ormond Street Children’s Charity, The Brain Tumour Charity, Children with Cancer UK, Cancer Research UK, NIHR and the Olivia Hodson Cancer Fund. All research at GOSH NHS Foundation Trust and UCL Great Ormond Street Institute of Child Health is made possible by the NIHR GOSH Biomedical Research Centre. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.