MutationsinmitochondrialtRNAgeneshavebeenshowntobeassociatedwithmaternallyinheritedsyn-dromicandnon-syndromicdeafness.Amongthose,mutationssuchastRNALeu(UUR)3243A>Gassociatedwithsyndromicdeafnessareoftenpresentinheteroplasmy,andthenon-syndromicdeafness-associatedtRNAmu-tationsincludingtRNASer(UCN)7445A>Gareofteninhomoplasmyorinhighlevelsofheteroplasmy.ThesetRNAmutationsaretheprimaryfactorsunderlyingthedevelopmentofhearingloss.However,othertRNAmutationssuchastRNAThr15927G>AandtRNASer(UCN)7444G>Aareinsufficienttoproduceadeafnessphe-notype,butalwaysactinsynergywiththeprimarymitochondrialDNAmutations,andcanmodulatetheirphenotypicmanifestation.ThesetRNAmutationsmayalterthestructureandfunctionofthecorrespondingmitochondrialtRNAsandcausefailuresintRNAsmetabolism.Thereby,theimpairmentofmitochondrialproteinsynthesisandsubsequentdefectsinrespirationcausedbythesetRNAmutations,resultsinmitochon-drialdysfunctionsandeventuallyleadstothedevelopmentofhearingloss.Here,wesummarizedthedeaf-ness-associatedmitochondrialtRNAmutationsanddiscussedthepathophysiologyofthesemitochondrialtRNAmutations,andwehopethesedatawillprovideafoundationfortheearlydiagnosis,management,andtreatmentofmaternallyinheriteddeafness.
