Mitochondrial Dna-Related Progressive External Ophthalmoplegia, also known as maternally-inherited chronic progressive external ophthalmoplegia, is related to chronic progressive external ophthalmoplegia and kearns-sayre syndrome. An important gene associated with Mitochondrial Dna-Related Progressive External Ophthalmoplegia is MT-TL2 (Mitochondrially Encoded TRNA-Leu (CUN) 2). Affiliated tissues include eye, and related phenotypes are progressive external ophthalmoplegia and muscle abnormality related to mitochondrial dysfunction