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Biomarkers of presbycusis and tinnitus in a Portuguese older population

Haider, Haula F.; Flook, Marisa; Aparicio, Mariana; Ribeiro, Diogo; Antunes, Marilia; Szczepek, Agnieszka J.; Hoare, Derek J.; Fialho, Graca; Paco, Joao; Caria, Helena

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Haula F. Haider

Marisa Flook

Mariana Aparicio

Diogo Ribeiro

Marilia Antunes

Agnieszka J. Szczepek

Associate Professor in Hearing Sciences

Graca Fialho

Joao Paco

Helena Caria


Introduction: Presbycusis or age-related hearing loss (ARHL) is a ubiquitous health problem. It is estimated that it will affect up to 1.5 billion people by 2025. In addition, tinnitus occurs in a large majority of cases with presbycusis. Glutamate metabotropic receptor 7 (GRM7) and N-acetyltransferase 2 (NAT2) are some of the genetic markers for presbycusis.

Objectives: To explore patterns of hearing loss and the role of GRM7 and NAT2 as possible markers of presbycusis and tinnitus in a Portuguese population sample.

Materials and Methods: Tonal and speech audiometry, tinnitus assessment, clinical interview, and DNA samples were obtained from patients aged from 55 to 75 with or without tinnitus. GRM7 analysis was performed by qPCR. Genotyping of single nucleotide polymorphisms (SNPs) in NAT2 was performed by PCR amplification followed by Sanger sequencing or by qPCR.

Results: We screened samples from 78 individuals (33 men and 45 women). T allele at GRM7 gene was the most observed (60.3% T/T and 33.3% A/T). Individuals with a T/T genotype have a higher risk for ARHL and 33% lower risk for tinnitus, compared to individuals with A/A and A/T genotype, respectively. Being a slow acetylator (53%) was the most common NAT2 phenotype, more common in men (55.8%). Intermediate acetylator was the second most common phenotype (35.9%) also more frequent in men (82.6%). Noise exposed individuals and individuals with ‘high frequency’ hearing loss seem to have a higher risk for tinnitus. Our data suggests that allele AT of GRM7 can have a statistically significant influence toward the severity of tinnitus.

Conclusion: For each increasing year of age the chance of HL increases by 9%. The risk for ARHL was not significantly associated with GRM7 neither NAT2. However, we cannot conclude from our data whether the presence of T allele at GRM7 increases the odds for ARHL or whether the A allele has a protective effect. Genotype A/T at GRM7 could potentially be considered a biomarker of tinnitus severity. This is the first study evaluating the effect of GRM7 and NAT2 gene in tinnitus.


Haider, H. F., Flook, M., Aparicio, M., Ribeiro, D., Antunes, M., Szczepek, A. J., …Caria, H. (2017). Biomarkers of presbycusis and tinnitus in a Portuguese older population. Frontiers in Aging Neuroscience, 9(346),

Journal Article Type Article
Acceptance Date Oct 16, 2017
Publication Date Nov 1, 2017
Deposit Date Feb 8, 2018
Publicly Available Date Feb 8, 2018
Journal Frontiers in Aging Neuroscience
Electronic ISSN 1663-4365
Publisher Frontiers Media
Peer Reviewed Peer Reviewed
Volume 9
Issue 346
Keywords presbycusis; GRM7; NAT2; tinnitus; markers; comorbidities
Public URL
Additional Information This Document is Protected by copyright and was first published by Frontiers. All rights reserved. it is reproduced with permission.


Haider et al_2017_Frontiers Neurosci.pdf (1.2 Mb)

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