Footnotes

• Contributors AC drafted the manuscript. JA provided critical review of the draft. Both authors approved the final version.

• Funding AC is a Clinical Research Training Fellow supported by the Wellcome Trust, Great Ormond Street Hospital Children's Charity and Great Ormond Street Hospital Biomedical Research Centre. JA is funded by the Great Ormond Street Charity leadership award and Great Ormond Street Hospital NIHR Biomedical Research Centre.

• Competing interests None declared.

• Provenance and peer review Commissioned; externally peer reviewed.