Natural history of conduction abnormalities in a patient with Kearns-Sayre syndrome.

Kearns-Sayre syndrome is a rare mitochondrial disorder characterized by large-scale deletion or rearrangement of mitochondrial DNA, which is usually not inherited but occur spontaneously probably at the germ cell level or very early in embryonic development by Mehndiratta et al. (Neurol India 50:162-167, 2002). Neuromuscular and cardiac conduction abnormalities are most commonly involved in these patients, which may have subtle presenting signs.