Genetics of Mitochondrial Aminoacyl-tRNA Synthetases Associated with Sensorineural Hearing Loss

Aminoacyl-tRNA synthetases are highly conserved proteins that catalyze the tRNA aminoacylation reaction to produce aminoacyl-tRNAs involved in protein synthesis, which are required to translate cytoplasmic and mitochondrial proteins. The mt-ARS genes encode the mitochondrial aminoacyl-tRNA synthetase (mt-ARSs), and variants in mt-ARS genes affect mitochondrial protein synthesis. This can impair the translation of mitochondrial proteins, adversely affecting oxidative phosphorylation and leading to related diseases. To date, 19 mt-ARS genes have been identified and found to be strongly associated with the development of mitochondrial disorders. Hearing loss (HL) is one of the most common chronic conditions in children and a leading cause of communication disorders. Genetic studies of sensorineural HL are critical to diagnosing and treating sensorineural HL. The relationship between mt-ARS genes and sensorineural HL is gradually surfacing as cases of HL phenotypes caused by variants in the mammalian mt-ARS genes continue to be reported. Seven mt-ARS genes have been reported to contribute to various hereditary sensorineural HL.

This article reviews studies on mitochondrial aminoacyl-tRNA synthetase, mt-ARS genes, and variants associated with HL phenotypes. Investigating their genetic characteristics provides deeper insights into the pathophysiology and molecular mechanisms of sensorineural hearing loss.

Disease phenotypes resulting from variants in mt-ARS genes exhibit significant clinical heterogeneity. The varying degrees of sensorineural HL phenotypes caused by mt-ARS gene variants warrant the attention of otologists and researchers. At least seven of the currently reported mt-ARS genes are associated with sensorineural HL. However, the molecular mechanisms by which these genes contribute to HL remain incompletely understood. Further studies of the mt-ARS genes still await additional case reports, as well as related model animal studies and combined functional studies.