Sir Douglass Matthew Turnbull, MD, PhD, MRCP, is a world leader in genetic disorders of mitochondria (cell's energy generators) as well as in aging and neurodegenerative disease. Dr. Turnbull's work has helped to define, diagnose and understand mitochondrial disease. Throughout his career, he has been instrumental in the development of new techniques, such as mitochondrial donation, one of the major advances in the field of mitochondrial genetics.

Dr. Turnbull's work has been crucial to understanding the role of mitochondrial DNA mutations -- changes in mitochondria's own DNA -- in aging and neurodegeneration. He and his colleagues first identified high levels of mitochondrial DNA deletions -- loss of parts of DNA -- in aged brain cells from substantia nigra, the dopamine-producing brain region damaged in PD. In addition to these scientific achievements, Dr. Turnbull leads one of the best clinics for patients with mitochondrial disease in the world and developed widely used guidelines for the care of patients with mitochondrial diseases.