Mitochondrially encoded tRNA leucine 1 (MT-TL1) m.3243A>G mutation (m.3243A>G)

The m.3243A>G mutation is a pathogenic point mutation located in the MT-TL1 gene of the mitochondrial DNA, which encodes the mitochondrial tRNA-Leu(UUR) [1.1.1, 1.1.2]. This mutation is the primary genetic cause of Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS) and Maternally Inherited Diabetes and Deafness (MIDD) [1.1.2, 1.1.3]. Biologically, the mutation disrupts the proper processing and taurinomethylation of the tRNA, leading to a defect in the translation of mitochondrial-encoded subunits of the respiratory chain and a subsequent failure in oxidative phosphorylation [1.1.1, 1.1.2]. Clinical manifestations are highly variable and depend on the level of heteroplasmy, or the ratio of mutant to wild-type DNA, within specific tissues [1.1.3, 1.5.1]. While traditional management focuses on supportive care with antioxidants and nitric oxide precursors like L-arginine, emerging therapies utilize precision gene-editing tools such as mitoARCUS and TALENs to selectively eliminate mutant genomes [1.2.4, 1.3.1, 1.4.4]. These novel approaches aim to shift the heteroplasmy level below the symptomatic threshold, offering a potential curative strategy for mitochondrial diseases that currently lack effective treatments [1.2.1, 1.3.3].

Other names

A3243G mutationMELAS mutationMT-TL1 m.3243A>GMitochondrial DNA 3243A>GtRNA-Leu(UUR) m.3243A>G

Therapeutic strategies include the selective cleavage and elimination of mutant mitochondrial DNA using engineered nucleases (e.g., ARCUS, TALENs) to shift heteroplasmy toward wild-type DNA, blocking mutant DNA replication with peptide nucleic acids, and providing metabolic support via antioxidants and nitric oxide precursors to mitigate respiratory chain dysfunction [1.2.1, 1.2.4, 1.3.3, 1.4.4].