Mitochondrial tRNA Valine in Cardiomyopathies

Abstract

Mitochondrial respiratory chain disorders are a heterogeneous group of diseases that clinically involve multiple tissues although they tend to mainly affect nervous system and skeletal muscle. The predominance of neurologic and neuromuscular manifestations in mitochondrial diseases has generally masked the presence of other, but not less important, clinical phenotypes, such as cardiac complications. Nowadays, mitochondrial defects are being increasingly recognized to play an important role in the pathogenesis of a subgroup of cardiomyopathies produced by defects in the energetic metabolism (mitochondrial cardiomyopathies). These diseases can result from mutations in either nuclear or mitochondrial encoded genes although mitochondrial DNA mutations are more frequent. In fact, cardiac conduction abnormalities have been associated with different mtDNA rearrangements. In a same way, sporadic or inherited mutations in mitochondrial DNA specifically in the mitochondrial transfer ribonucleic acid genes (mostly in the tRNA^Leu(UUR) and tRNA^Ile) have also been associated with hypertrophic and dilated cardiomyopathy. Mitochondrial diseases caused by mutations in the mitochondrial tRNA^Val gene (MT-TV) are not very frequent. However, a relatively high percentage of mutations in this gene have been associated with mitochondrial cardiomyopathy. Besides, functional and molecular analyses suggest that the MT-TV gene should be routinely considered in the diagnosis when there is a high suspicion of mitochondrial cardiomyopathy. Finally, the increasingly importance of the role that this gene has begun to play in the pathophysiology of mitochondrial cardiomyopathies indicates that future studies about the molecular mechanisms that could explain why the cardiomyopathy phenotype appears must be carried out.