Mitochondrial tRNA leucine 1 (UUR) containing m.3243A>G mutation (MT-TL1 m.3243A>G)

The m.3243A>G mutation is a pathogenic point mutation in mitochondrial DNA (mtDNA) at position 3243, located in the MT-TL1 gene encoding mitochondrial tRNA leucine 1 (UUR)[1][3][5]. It is the most prevalent pathogenic mtDNA mutation, with a heteroplasmic distribution (mixture of wild-type and mutant mtDNA) in cells[1][3][7]. This mutation impairs tRNA^Leu(UUR)^ structure, stability, methylation, and aminoacylation, leading to defective mitochondrial protein synthesis and dysfunction of oxidative phosphorylation (OXPHOS)[1]. The resulting mitochondrial dysfunction underlies a spectrum of clinical phenotypes, the most classic being MELAS syndrome[5], while others include maternally inherited diabetes and deafness (MIDD), cardiomyopathy, and more[3][7][9]. No currently approved drugs directly target this mutant tRNA, but mitochondrial DNA—inclusive of the m.3243A>G mutation—has become an active therapeutic target in research for cancer, metabolic, and neurodegenerative diseases[2][4][6][8]. Disease management is symptomatic and supportive, with ongoing investigation into gene therapies and mitochondrial replacement techniques[1][10]. Diagnostic and prognostic assessment relies on detecting and quantifying the mutation in relevant tissues[5]. The high clinical variability and complex inheritance patterns make this mutation a major challenge in mitochondrial medicine.

Other names

m.3243A>G mutant mitochondrial DNAMELAS mutationMT-TL1 3243A>Gmitochondrial DNA mutation m.3243A>G

For experimental strategies: targeted cleavage or modification of mutant mtDNA, or altering mitochondrial translation and biogenesis pathways[2][6][8]