Natural History of Leigh Syndrome: A Study of Disease Burden and Progression.

"Potential Conflicts of Interest Nothing to report."

"This work was supported by the Wellcome Centre for Mitochondrial Research (203105/Z/16/Z), the Newcastle University Centre for Ageing and Vitality (supported by the Biotechnology and Biological Sciences Research Council and Medical Research Council L016354), the UK National Institute for Health Research (NIHR) Biomedical Research Centre (BRC) for Ageing and Age‐Related Disease award to the Newcastle Upon Tyne Hospitals National Health Service (NHS) Foundation Trust, NIHR, and the UK NHS Specialist Commissioners, which fund the Rare Mitochondrial Disorders of Adults and Children Diagnostic Service in Newcastle upon Tyne (http://www.newcastle-mitochondria.com/). R.M. and R.W.T. receive funding from the Medical Research Council International Centre for Genomic Medicine in Neuromuscular Disease (MR/S005021/1). R.W.T. is also funded by the Pathology Society. C.L.A. is supported by an NIHR postdoctoral fellowship (PDF‐2018‐11‐ST2‐021). This work also received infrastructure support from the NIHR BRC, Newcastle and North Tyneside Comprehensive Local Research Network. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the BRC, or the Department of Health. We thank D. Jerry, Data Manager of the MitoCohort UK, the staff of the NHS Highly Specialised Rare Mitochondrial Disorders Service diagnostic laboratory in Newcastle upon Tyne, and all of the UK clinicians who refer patients to our clinical service for their support."