Exophthalmos in Kearns-Sayre syndrome.

Kearns-Sayre syndrome (KSS) is a rare mitochondrial DNA (mtDNA) deletion syndrome that typically presents before 20 years of age and is characterized by chronic progressive external ophthalmoplegia, pigmentary retinopathy, and a combination of cardiac conduction defects, cerebellar ataxia, and elevated cerebrospinal fluid protein levels. The mtDNA defects interfere with oxidative phosphorylation and can affect a number of cellular energy processes in various organs. We report the case of a 15-year-old girl with KSS that was uniquely associated with bilateral, symmetrical exophthalmos.