Association Analysis of Candidate Gene Polymorphisms and Tinnitus in Young Musicians

A Systematic Review on the Genetic Contribution to Tinnitus

PURPOSE

To assess the available evidence to support a genetic contribution and define the role of common and rare variants in tinnitus.

METHODS

After a systematic search and quality assessment, 31 records including 383,063 patients were selected (14 epidemiological studies and 17 genetic association studies). General information on the sample size, age, sex, tinnitus prevalence, severe tinnitus distribution, and sensorineural hearing loss was retrieved. Studies that did not include data on hearing assessment were excluded. Relative frequencies were used for qualitative variables to compare different studies and to obtain average values. Genetic variants and genes were listed and clustered according to their potential role in tinnitus development.

RESULTS

The average prevalence of tinnitus estimated from population-based studies was 26.3% for any tinnitus, and 20% of patients with tinnitus reported it as an annoying symptom. One study has reported population-specific differences in the prevalence of tinnitus, the white ancestry being the population with a higher prevalence. Genome-wide association studies have identified and replicated two common variants in the Chinese population (rs2846071; rs4149577) in the intron of TNFRSF1A, associated with noise-induced tinnitus. Moreover, gene burden analyses in sequencing data from Spanish and Swede patients with severe tinnitus have identified and replicated ANK2, AKAP9, and TSC2 genes.

CONCLUSIONS

The genetic contribution to tinnitus is starting to be revealed and it shows population-specific effects in European and Asian populations. The common allelic variants associated with tinnitus that showed replication are associated with noise-induced tinnitus. Although severe tinnitus has been associated with rare variants with large effect, their role on hearing or hyperacusis has not been established.

The potassium channels: Neurobiology and pharmacology of tinnitus

Tinnitus is a widespread public health issue that imposes a significant social burden. The occurrence and maintenance of tinnitus have been shown to be associated with abnormal neuronal activity in the auditory pathway. Based on this view, neurobiological and pharmacological developments in tinnitus focus on ion channels and synaptic neurotransmitter receptors in neurons in the auditory pathway. With major breakthroughs in the pathophysiology and research methodology of tinnitus in recent years, the role of the largest family of ion channels, potassium ion channels, in modulating the excitability of neurons involved in tinnitus has been increasingly demonstrated. More and more potassium channels involved in the neural mechanism of tinnitus have been discovered, and corresponding drugs have been developed. In this article, we review animal (mouse, rat, hamster, and guinea-pig), human, and genetic studies on the different potassium channels involved in tinnitus, analyze the limitations of current clinical research on potassium channels, and propose future prospects. The aim of this review is to promote the understanding of the role of potassium ion channels in tinnitus and to advance the development of drugs targeting potassium ion channels for tinnitus.

Young Adults' Knowledge and Perceptions of Permanent Noise-Induced Tinnitus and its Influence on Behavioural Intentions

Objective

Young adults' music-listening behaviours may put them at risk of developing permanent hearing loss and tinnitus. This study aimed to assess knowledge of permanent tinnitus and whether this knowledge may influence listening behaviours to a greater degree than knowledge of hearing loss.

Materials and Methods

A two-group (between subjects), randomised post-test only, single-factor experimental design was used to determine the effects of health message focus (permanent tinnitus vs. permanent hearing loss) on the main outcome measure of protective behavioural intention. The sample included 109 male and 287 female adults, aged 18 to 25 years, living in the United Kingdom. The young adults' existing knowledge of either permanent hearing loss or permanent tinnitus was measured, and after exposure to a health message, their perceptions and resultant behavioural intentions were assessed and compared. The pooled data were used to test a proposed model of factors influencing hearing protective behavioural intention using path analysis.

Results

Whilst 83% knew about the link with hearing loss, only 75% knew that loud music may cause permanent tinnitus. The participants viewed tinnitus as closer temporally than hearing loss, perceived themselves as equally susceptible to both, but perceived hearing loss as more severe. There was no significant difference in behavioural intention between the groups.

Conclusion

Perceived susceptibility and severity have a positive effect on behavioural intentions. In light of these results, recommendations for future noise-damage prevention campaigns are made.