Kearns-Sayre syndrome
Kearns-Sayre syndrome (KSS) is a disease caused by mutations in the mitochondrial DNA. As such, it is a rare genetic disease in that it can be heteroplasmic, that is, more than one genome can be in a cell at any given time.
Its expression is systemic, but many of the most common expressions are in the eyes, with ophthalmoplegia a common feature.