Part I. Introduction to Mitochondrial Medicine: 1. Mitochondria in health and disease Carlo Viscomi and Massimo Zeviani; 2. Clinical approach in children Shamima Rahman; 3. Clinical approach in adults Michael J. Keogh, Hannah E. Steele and Patrick F. Chinnery; 4. Laboratory investigation of mitochondrial diseases Robert W. Taylor and David R. Thorburn; 5. Clinical genetics of mitochondrial diseases Marni J. Falk and Colleen Clarke Muraresku; 6. Clinical management of mitochondrial diseases Rita Horvath; Part II. Systems Involved in Mitochondrial Diseases: 7. Neurology – the central nervous system Michael J. Keogh, Hannah E. Steele and Patrick F. Chinnery; 8. Neurology – the peripheral nervous system – muscle and nerve Robert D. S. Pitceathly, Michael G. Hanna and Mary M. Reilly; 9. Ophthalmology Patrick Yu-Wai-Man, Chiara La Morgia and Valerio Carelli; 10. Audiology Peter Kullar; 11. Cardiovascular medicine Michael J. Keogh, Hannah E. Steele and Patrick F. Chinnery; 12. Respiratory medicine and anaesthesiology Michael J. Keogh, Hannah E. Steele and Patrick F. Chinnery; 12. Respiratory medicine and anaesthesiology Philip G. Morgan and Margaret M. Sedensky; 13. Endocrinology and diabetes Mark Walker, Alison J. Heggie, Andrew M. Schaefer and Grainne S. Gorman; 14. Gastroenterology and hepatology Irenaeus F. M. de Coo and Jessie M. Hulst; 15. Nephrology Thomas M. F. Connor and Patrick H. Maxwell; 16. Psychiatry Laurence A. Bindoff