ORGAN DISTRIBUTION OF MUTANT MITOCHONDRIAL TRANSFER RNA(LEU(UUR)) GENE IN A MELAS PATIENT

Point mutations in the mitochondrial tRNA(leu(UUR)) gene have been rec ently reported in patients with mitochondrial myopathy, encephalopathy , lactic acidosis and stroke-like episodes (MELAS). To investigate the relationship between the degree of heteroplasmy and the organ damage, the ratio of mutant and wildtype genes was quantitated in 14 differen t organs obtained at an autopsy case of MELAS. The percentages of mito chondrial tRNA(leu(UUR)) gene carrying an A to G transition mutation a t nucleotide 3243 were determined by the restriction enzyme digestion of the polymerase chain reaction products. The organs largely dependin g on oxidative phosphorylation for the sources of energy contained hig her proportions of the mutant tRNA(leu(UUR)) gene than organs with a l ower oxygen demand. However, the percentage of the mutant genes was si milar in both symptomatic and asymptomatic organs with a higher oxygen demand.