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Year: 2013  Vol. 17   Num. Suppl. 1  - Print:
12º CONGRESSO DA FUNDAÇÃO OTORRINOLARINGOLOGIA - Oral Presentation Otorhinolaryngology
INVESTIGATING DEAFNESS GENES AS A CAUSE OF SUDDEN SENSORINEURAL HEARING LOSS
Author(s):
Jeanne Oiticica, Dayane Bernardino-Cruz, Lia Tacia Costa Cavalcante, Maria Teresa Balester de Mello Auricchio, Regina Célia Mingroni Netto, Roseli Saraiva Moreira Bittar
Abstract:

INTRODUCTION: Sudden sensorineural hearing loss (SSNHL) is defined as sensorineural hearing loss equal or greater than 30 dB HL, affecting at least 3 consecutive tonal frequencies, and with sudden onset, occurring within 3 days. Some individuals with deafness from mitochondrial mutations are described as having SSNHL. OBJECTIVE: The aim of this work was to investigate the role of genetic factors in the etiology of SSNHL. METHODS: In order to achieve this, we screened mutations in the GJB2 and GJB2 genes and sequenced the mitochondrial genes MTRNR1, MTTS1, and MTTL1, in 53 individuals with SSNHL. RESULTS: The mutations c.35delG and c.167delT and the deletions del (GJB6-D13S1830) and del (GJB6-D13S1854) were not found in the sample. Variants in MTTS1 and MTTL1 genes were not detected, either. Regarding the MTRNR1 gene, 15 different variants were found, 13 of which were described as having no phenotypic effect. Two novel mutations (m.806C>T and m.986G>A) were not reported in the SNP database and were not found in a Brazilian control sample of 104 individuals with normal hearing (Abreu-Silva et al., Ann Hum Biol, 2011, 38(2):210-8); their importance still needs to be clarified through population studies. CONCLUSION: Although molecular screening did point to a significant role of the tested genes in SSNHL, it is noteworthy that 20 (37.7%) of the 53 subjects with SSNHL reported a positive familial history of hearing loss, compared to 19 (18.2%) of the individuals with normal hearing. These data suggest genetic susceptibility to hearing loss in the SSNHL group probably results from multifactorial mechanisms.

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