Increased mitochondrial processing intermediates associated with three tRNA(Leu(UUR)) gene mutations.

Accumulation of RNA 19 has been associated with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes. We analyzed total RNA in muscle specimens from six patients who had one of three pathogenetic point mutations in the mitochondrial tRNA(Leu(UUR)) gene, including A3243G, T3271C, and T3303C. Mitochondrial processing intermediates were identified and quantitated by Northern blotting.