FREQUENCY OF MITOCHONDRIAL MUTATION C1494T, OF THE GENE MT-RNR1, IN COHORTS OF BRAZILIAN HEARING AND DEAF PEOPLE

Abstract

Introduction: Deafness is the most common sensory deficit in humans, which may be caused by environmental and genetic factors or even by a combination of both. It has been estimated that one in every 500 newborns has bilateral permanent hearing loss, and this incidence increases to 3.5:1,000 individuals in adolescence. Certain environmental factors may be enhanced when specific mutations are present in the genome. It is widely known that the use aminoglycoside antibiotics may lead to hearing loss, especially if the individual has predisposing mitochondrial mutations. Mutation C1494T of the mitochondrial gene MT-RNR1 which causes the formation of the subunit 12S of the ribosome RNA (12S rRNA), has been associated with hearing loss due to the use of aminoglycoside antibiotics. Objective: This study investigates the occurrence of mitochondrial mutation C1494T in the gene MT-RNR1 in cohorts of hearing and deaf people in northern and northwestern regions of Paraná state, Brazil. Material and Methods: Eighty hearing people and eighty deaf people were analyzed. The latter were characterized as pre-lingual, non-syndromic, of unknown etiology, being isolated cases within the family. PCR technique was used for amplification of the fragment 936 bp of the gene MT-RNR1 at position 1494, followed by digestion with restriction enzyme Hph I. Results: Mutation C1494T was not detected in the samples of hearing and deaf people. Conclusions: Mutation C1494T of the gene MT-RNR1 may be absent or rare in populations of hearing and deaf people in northern and northwestern regions of Paraná state, Brazil. DESCRIPTORS Deafness. Hearing Loss. Mitochondrial Genes.