MULTIPLE MITOCHONDRIAL-DNA DELETIONS ASSOCIATED WITH AUTOSOMAL RECESSIVE OPHTHALMOPLEGIA AND SEVERE CARDIOMYOPATHY

Six patients in two unrelated families from the eastern Arabian penins ula presented with childhood-onset progressive external ophthalmoplegi a (PEG), mild facial and proximal limb weakness, and severe cardiomyop athy requiring cardiac transplantation. Muscle biopsies showed ragged- red and cytochrome c oxidase-negative fibers. The activities of severa l complexes in the electron-transport chain were decreased and Souther n blot analysis showed multiple mtDNA deletions. The apparent autosoma l-recessive inheritance and the association with cardiomyopathy distin guish this syndrome from autosomal-dominant PEO with multiple mtDNA de letions. The combination of autosomal-recessive PEG, cardiomyopathy, a nd multiple mtDNA deletions appears to be another disease due to a def ect of communication between the nuclear and mitochondrial genomes.