MITOCHONDRIAL-DNA DELETION IN A PATIENT WITH MITOCHONDRIAL MYOPATHY, LACTIC-ACIDOSIS, AND STROKE-LIKE EPISODES (MELAS) AND FANCONIS-SYNDROME

Large-scale mitochondrial DNA deletion was found in a 5-year-old girl with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) and Fanconi's syndrome. Muscle biopsy disclosed ragged-red fibers and cytochrome c oxidase negative fibers, Respiratory chain studies were normal, Southern blot analysis demonstrated a 10,5-Kb heteroplasmic deletion in both muscle and blood, Deleted genomes represented 40% of total mitochondrial DNA in muscle and 63% in blood. There was no evidence of point mutations characteristic of MELAS, We suggest that not only patients with progressive external ophthalmoplegia syndromes, but also those with defined syndromes [e,g., MELAS or myoclonic epilepsy and ragged-red fibers (MERRF)] without characteristic point mutations, be screened for mitochondrial DNA deletions.