Risk Of Noise-induced Hearing Loss Research Articles

“Know Your Noise” Helps Young People Understand Risks Associated with Recreational Noise Exposure and Take Action to Prevent Hearing Damage

The Know Your Noise website was developed to provide accurate and personalized information about hearing health to increase users’ awareness of the risk for noise-induced hearing loss and increase their likelihood to undertake behavior change to reduce their exposure. This study aimed to examine the effectiveness of the site in meeting these goals. User engagement via google analytics showed good engagement with the site itself across a range of demographics. Results from an online evaluation survey indicated improvement in hearing health engagement following participation, particularly for those shown to be most at risk.

NRN1 and CAT Gene Polymorphisms, Complex Noise, and Lifestyles interactively Affect the Risk of Noise-induced Hearing Loss

ObjectiveThe effects of interactions between genetic and environmental factors on the noise-induced hearing loss (NIHL) are still unclear. This study aimed to assess interactions among gene polymorphisms, noise metrics, and lifestyles on the risk of NIHL. MethodsA case-control study was conducted using 307 patients with NIHL and 307 matched healthy individuals from five manufacturing industries. General demographic data, lifestyle details, and noise exposure levels were recorded. The Kompetitive allele-specific polymerase chain reaction (KASP) was used to analyze the genotypes of 18 SNPs. ResultsGMDR model demonstrated a relevant interaction between NRN1 rs3805789 and CAT rs7943316 (P = 0.0107). Subjects with T allele of rs3805789 or T allele of rs7943316 had higher risks of NIHL than those with the SNP pair of rs3805789-CC and rs7943316-AA (P < 0.05). There was an interaction among rs3805789, rs7943316, and kurtosis (P = 0.0010). Subjects exposed to complex noise and carrying both rs3805789-CT and rs7943316-TT or rs3805789-CT/TT and rs7943316-AA had higher risks of NIHL than those exposed to steady noise and carrying both rs3805789-CC and rs7943316-AA (P < 0.05). The best six-locus model involving NRN1 rs3805789, CAT rs7943316, smoking, video volume, physical exercise, and working pressure for the risk of NIHL was found to be the interaction (P = 0.0010). An interaction was also found among smoking, video volume, physical exercise, working pressure, and kurtosis (P = 0.0107). ConclusionConcurrence of NRN1 and CAT constitutes a genetic risk factor for NIHL. Complex noise exposure significantly increases the risk of NIHL in subjects with a high genetic risk score. Interactions between genes and lifestyles as well as noise metrics and lifestyles affect the risk of NIHL.

Comparative analysis of the potential and actual risk of noise-induced hearing loss in employees of “noise” industries

Introduction. The high incidence of noise-induced hearing loss (NIHL) makes it possible to attribute the problem of prevention and prediction of the risk of NIHL to the number of socially significant ones. The aim of the study is to conduct a comparative assessment of the potential risk of hearing loss caused by noise according to GOST R ISO 1999-2017, and the actual risk of NIHL in workers of “noise” industries according to epidemiological research. Materials and methods. The calculation of the potential risk of hearing loss according to GOST R ISO 1999-2017 included assessing age, noise and total hearing loss at noise exposure with 85, 90, 95 and 100 dBA. The actual risk of NIHL was evaluated on survey data of 600 miners and 600 workers of processing plants. Results. The calculation of the probable risk according to GOST R ISO 1999-2017 and the assessment of the actual risk according to epidemiological studies showed that the risk of NIHL depends on both noise exposure and age. As the levels of noise affecting an employee increase, the risk of an NIHL becomes more determined by the effect of noise. At noise levels 85, 90 and 95 dBA, the probable risk calculated under GOST R ISO 1999-2017 coincides with the actual risk established according to epidemiological studies. At the same time, for miners exposed to high-intensity noise 100 dBА, the real risk was not as high as could be assumed from the calculated data. Conclusion. The results obtained allow stating that the GOST ISO 1999-2017 standard with a high degree of potential risk allows predicting the group risk of hearing loss due to noise exposure, to quantify the degree of risk and can be used for the formation of risk groups for NIHL and the development of programs for the preservation of hearing.

A missense variant rs2585405 in clock gene PER1 is associated with the increased risk of noise-induced hearing loss in a Chinese occupational population

ObjectiveTo investigate the potential association of cochlear clock genes (CRY1, CRY2, PER1, and PER2), the DNF gene (brain-derived neurotrophic factor), and the NTF3 gene (neurotrophin3) with susceptivity to noise-induced hearing loss (NIHL) among Chinese noise-exposed workers.MethodsA nested case–control study was performed with 2056 noise-exposed workers from a chemical fiber factory and an energy company who underwent occupational health examinations in 2019 as study subjects. Propensity score matching was conducted to screen cases and controls by matching sex, age, and the consumption of tobacco and alcohol. A total of 1269 participants were enrolled. Then, general information and noise exposure of the study subjects were obtained through a questionnaire survey and on-site noise detection. According to the results of audiological evaluations, the participants were divided into the case group (n = 432, high-frequency threshold shift > 25 dB) and the matched control group (n = 837, high-frequency threshold shift ≤ 25 dB) by propensity score matching. Genotyping for PER1 rs2253820 and rs2585405; PER2 rs56386336 and rs934945; CRY1 rs1056560 and rs3809236; CRY2 rs2292910 and rs6798; BDNF rs11030099, rs7124442 and rs6265; and NTF3 rs1805149 was conducted using the TaqMan-PCR technique.ResultsIn the dominant model and the co-dominant model, the distribution of PER1 rs2585405 genotypes between the case group and the control group was significantly different (P = 0.03, P = 0.01). The NIHL risk of the subjects with the GC genotype was 1.41 times the risk of those carrying the GG genotype (95% confidence interval (CI) of odds ratio (OR): 1.01–1.96), and the NIHL risk of the subjects with the CC genotype was 0.93 times the risk of those carrying the GG genotype (95%CI of OR: 0.71–1.21). After the noise exposure period and noise exposure intensities were stratified, in the co-dominant model, the adjusted OR values for noise intensities of ≤ 85 was 1.23 (95%CI: 0.99–1.53). In the dominant model, the adjusted OR values for noise exposure periods of ≤ 16 years and noise intensities of ≤ 85 were 1.88 (95%CI: 1.03–3.42) and 1.64 (95%CI: 1.12–2.38), respectively.ConclusionThe CC/CG genotype of rs2585405 in the PER1 gene was identified as a potential risk factor for NIHL in Chinese noise-exposed workers, and interaction between rs2585405 and high temperature was found to be associated with NIHL risk.

Surrounded by Sound: The Impact of Tinnitus on Musicians.

AIM: To investigate the impact of tinnitus on professional musicians in the UK. BACKGROUND: Tinnitus is the experience of sound when an external source is absent, primarily associated with the ageing process, hearing loss, and noise exposure. Amongst populations exposed to industrial noise, noise exposure and noise-induced hearing loss (NIHL) have been found to be the factors most associated with tinnitus. The risk of NIHL amongst professional musicians is greater than that amongst the general population, meaning they may be at increased risk of tinnitus. METHODS: Seventy-four professional musicians completed an online survey involving closed and open-ended questions, and completed the Tinnitus fuctional Index (TFI) questionnaire. Descriptive statistics and thematic analysis of open-ended qualitative responses were used to analyse the data. RESULTS: Three themes were generated from the analysis of the responses to the open-ended questions. These themes were: (1) the impact of tinnitus on the lives of professional musicians, (2) professional musician experience of tinnitus services, support, and hearing health and safety, and (3) the support professional musicians want. The mean global TFI score for professional musicians was 39.05, interpreted as tinnitus being a moderate problem. Comparisons with general population data revealed lower TFI scores for the TFI subscales of ‘sense of control’ and ‘intrusiveness’ for professional musicians and higher for auditory difficulties associated with tinnitus amongst professional musicians. CONCLUSION: Tinnitus can negatively impact on professional musicians’ lives. There is a need for bespoke self-help groups, awareness raising, and education to prevent tinnitus and promote hearing health among musicians.

Applying Kurtosis as an Indirect Metric of Noise Temporal Structure in the Assessment of Hearing Loss Associated With Occupational Complex Noise Exposure.

Objective:The association of occupational noise-induced hearing loss (NIHL) with noise energy was well documented, but the relationship between occupational noise and noise temporal structure is rarely reported. The objective of this study was to investigate the principal characteristics of the relationship between occupational NIHL and the temporal structure of noise.Methods:Audiometric and shift-long noise exposure data were collected from 3102 Chinese manufacturing workers from six typical industries through a cross-sectional survey. In data analysis, A-weighted 8-h equivalent SPL (LAeq.8h), peak SPL, and cumulative noise exposure (CNE) were used as noise energy indicators, while kurtosis (β) was used as the indicator of noise temporal structure. Two NIHL were defined: (1) high-frequency noise-induced hearing loss (HFNIHL) and (2) noise-induced permanent threshold shift at test frequencies of 3, 4, and 6 kHz (noise-induced permanent threshold shift [NIPTS346]). The noise characteristics of different types of work and the relationship between these characteristics and the prevalence of NIHL were analyzed.Results:The noise waveform shape, with a specific noise kurtosis, was unique to each type of work. Approximately 27.92% of manufacturing workers suffered from HFNIHL, with a mean NIPTS346 of 24.16 ± 14.13 dB HL. The Spearman correlation analysis showed that the kurtosis value was significantly correlated with the difference of peak SPL minus its LAeq.8h across different types of work (p < 0.01). For a kurtosis-adjusted CNE, the linear regression equation between HFNIHL% and CNE for complex noise almost overlapped with Gaussian noise. Binary logistic regression analysis showed that LAeq.8h, kurtosis, and exposure duration were the key factors influencing HFNIHL% (p < 0.01). The notching extent in NIPTS at 4 kHz became deeper with the increase in LAeq.8h and kurtosis. HFNIHL% increased most rapidly during the first 10 years of exposure. HFNIHL% with β ≥ 10 was significantly higher than that with β < 10 (p < 0.05), and it increased with increasing kurtosis across different CNE or LAeq.8h levels. When LAeq.8h was 80 to 85 dB(A), the HFNIHL% at β ≥ 100 was significantly higher than that at 10 ≤ β < 100 or β < 10 (p < 0.05 and p < 0.01, respectively).Conclusions:In the evaluation of hearing loss caused by complex noise, not only noise energy but also the temporal structure of noise must be considered. Kurtosis of noise is an indirect metric that is sensitive to the presence of impulsive components in complex noise exposure, and thus, it could be useful for quantifying the risk for NIHL. It is necessary to re-evaluate the safety of permissible exposure limit of 85 dB(A) as noise with a high kurtosis value can aggravate or accelerate early NIHL.

Noise-Induced Hearing Loss and Associated Genes

Noise-induced hearing loss (NIHL) is the most common occupational disease in the world and is the second most important cause of sensorineural hearing loss. Genetic and environmental factors are effective in the emergence of the disease. The World Health Organization (WHO) and the National Institute for Occupational Safety and Health (NIOSH) have classified NIHL as a research priority group. In this review, it is aimed to reveal the role of genetic variations and gene expression changes associated with susceptibility to noise-induced hearing loss in susceptibility to noise exposure. It can be said that genetic variations in heat shock protein 70 (Hsp70), 8-oxoG DNA glycosylase 1 (OGG1), Glutathione S-transferase M1 (GSTM1), catalase (CAT), Cadherin-23 (CDH23), Potassium Voltage Gated Channel Subfamily E Regulatory Subunit 1 (KCNE1) genes are associated with the risk of NIHL. Oxidative stress genes, inner ear potassium recycle pathway genes and monogenic hearing loss genes are accepted as candidate genes as genetic factors in NIHL. Individuals exposed to noise and at higher risk of developing NIHL are exposed to other environmental factors that interact with possible NIHL genes. More frequent use of high-throughput genotyping methods will allow the detection of multiple SNPs in a single sequence, making it possible to identify new NIHL susceptibility genes. This includes identifying individuals at high risk of developing NIHL and providing better hearing protection for susceptible individuals for noise-induced hearing loss. Thus, it could allow the development of genetic tests to help personalize treatment. Keywords: GBİK, occupational disease, genetic variations Special Issue of Health Sciences DOI: 10.7176/JSTR/7-08-07

Noise Exposure and Evaluation at Tire- Changing Facilities.

Thirty (30) personal noise-exposure samples were collected on 20 tire-changing and repair technicians in three tire-changing facilities to determine their personal noise exposures and to estimate the maximum number of tire changes that could be performed without exceeding occupational exposure limits. Of the 30 projected 8-h time-weighted average noise samples, none exceeded the Occupational Safety and Health Administration's Permissible Exposure Limit, 1 (3%) exceeded the Occupational Safety and Health Administration's Action Level, and 18 (60%) exceeded the American Conference for Governmental Industrial Hygienists Threshold limit Value of 85 dBA, indicating the need for a hearing loss prevention program. The average shift time for the technicians was 6 h and 42 min and the average number of tire changes was 18. Based on the projected 8-h noise exposure 95% upper confidence limits, the estimated maximum number of tires that could be changed without exceeding the Occupational Safety and Health Administration's noise action level was 32 tires, the permissible exposure limit greater than 40 tires, and the American Conference of Industrial Hygienists' Threshold Limit Value was less than 20 tires. In addition, area noise samples of tire-changing equipment were taken with a sound-level meter to identify the noise sources that contributed to the tire technicians' exposures. The air ratchet, tire-changing machine, and tire-bead seater were measured at noise levels >85 dBA, increasing the risk of noise-induced hearing loss to the technicians.

Feasibility of a daily noise monitoring intervention for prevention of noise-induced hearing loss

BackgroundDespite the existence of hearing conservation programmes complying with regulatory standards, noise-induced hearing loss (NIHL) remains one of the most prevalent occupational diseases. Compulsory daily monitoring of noise exposure has...

Hearing Function among Squadron 11/Attack Helicopter Pilots in 2019–2020

Noise-Induced Hearing Loss (NIHL) is sensorineural deafness resulting from prolonged exposure to loud noise. In the military environment, personnel with NIHL are often found. One of the professions that are at risk for NIHL is an aviator. Some of the factors that influence the degree of deafness are age and length of work. This research is a descriptive quantitative observational study with a cross-sectional design. The research subjects were Squadron 11/Attack helicopter pilots at Achmad Yani Air Base, Semarang, totaling 32 pilots, which were taken from medical record data. Sampling was done by total sampling. The data obtained were processed using SPSS and grouped into tables accompanied by descriptive explanations of each characteristic. The audiogram results showed that 32 pilots were normal, across all age and length of service categories. This result is due to the appropriate use of hearing protection device (HPD), in the form of a helmet that reduces noise up to 14 dB at 250 Hz, 21 dB at 1000 Hz, 26 dB at 2000 Hz, 37 dB at 4000 Hz, and 42 dB at a frequency of 8000 Hz, which pilots use. The pilot's working time is relatively short with a flight training schedule only 2 times a week and a flight time of around 2-3 hours. The conclusions of the study showed a description of normal hearing function in all Squadron 11/Attack helicopter pilots, based on age and length of service.

Targeted binding of rs1053005 locus of STAT3 with miR-452-3p and the association between STAT3 gene polymorphism and noise-induced hearing loss

Objective: To investigate the relationship between rs1053005 of signal conversion and transcription activator 3 (STAT3) and miR-452-3p, and the association between STAT3 gene polymorphism and noise-induced hearing loss (NIHL) . Methods: In December 2017, 1220 workers were selected from an automobile manufacturing factory, an energy company and a chemical fiber factory in Jiangsu Province who had occupational noise exposure and working age of more than 3 years. The workers with the mean hearing threshold of ≥26 dB (A) of the two ear high frequency (3000, 4000 and 6000 Hz) were defined as case group (n=609) , and the rest were control group (n=611) . Five single nucleotide polymorphism (SNP) sites of STAT3 (rs4796793, rs1053023, rs1053005, rs1053004 and rs3744483) were selected to explore the association between STAT3 gene polymorphism and NIHL by analyzing the points. The double luciferase reporter gene verified whether miR-452-3p was targeted to bind STAT3, and overexpressed miR-452-3p in HEI-OC1 cells to explore the mechanism of STAT3 expression regulation. Results: There was no significant difference in gender, age, smoking and drinking between the two groups (P>0.05) . Compared with the control group[ (15.58±4.76) dB], the mean hearing threshold of the case group [ (37.50±12.39) dB] was higher, and the difference were statistically significant (P<0.05) . Compared with the control group, the C alleles of rs1053023 and rs1053005 were higher in the case group (OR=1.367, 1.370, P<0.05) . The risk of NIHL in men with TC/CC genotype were 1.545 and 1.531 times higher than that in men with TT genotype (P<0.05) . Compared with the control group, the mRNA expression of STAT3 in the case group was significantly increased (P<0.05) . The STAT3 mRNA expression of miR-452-3p group cells was significantly decreased (P<0.05) . Conclusion: The rs1053023 and rs1053005 polymorphism of STAT3 are related to NIHL. The C alleles of rs1053023 and rs1053005 may be biomarkers of workers exposed to noise.

Identifying genetic risk variants associated with noise-induced hearing loss based on a novel strategy for evaluating individual susceptibility

BackgroundThe overall genetic profile for noise-induced hearing loss (NIHL) remains elusive. Herein we proposed a novel machine learning (ML) based strategy to evaluate individual susceptibility to NIHL and identify the underlying genetic risk variants based on a subsample of participants with extreme phenotypes. MethodsFive features (age, sex, cumulative noise exposure [CNE], smoking, and alcohol drinking status) of 5,539 shipbuilding workers from large cross-sectional surveys were included in four ML classification models to predict their hearing levels. The area under the curve (AUC) and prediction accuracy were exploited to evaluate the performance of the models. Based on the prediction error of the ML models, the NIHL-susceptible group (n=150) and NIHL-resistant group (n=150) with a paradoxical relationship between hearing levels and features were separately screened, to identify the underlying variants associated with NIHL risk using whole-exome sequencing (WES). Subsequently, candidate risk variants were validated in an additional replication cohort (n=2108), followed by a meta-analysis. ResultsWith 10-fold cross-validation, the performances of the four ML models were robust and similar, with average AUCs and accuracies ranging from 0.783 to 0.798 and 73.7% to 73.8%, respectively. The phenotypes of the NIHL-susceptible and NIHL-resistant groups were significantly different (all p<0.001). After WES analysis and filtering, 12 risk variants contributing to NIHL susceptibility were identified and replicated. The meta-analyses showed that the A allele of CDH23 rs41281334 (odds ratio [OR]=1.506, 95% confidence interval [CI]=1.106-2.051) and the C allele of WHRN rs12339210 (OR=3.06, 95% CI=1.398-6.700) were significantly associated with increased risk of NIHL after adjustment for confounding factors. ConclusionsThis study revealed two genetic variants in CDH23 rs41281334 and WHRN rs12339210 that associated with NIHL risk, based on a promising approach for evaluating individual susceptibility using ML models.

Modeling individual noise-induced hearing loss risk with proxy measurements of external-ear amplification.

Significant variability in noise-induced hearing loss (NIHL) susceptibility suggests there are factors beyond sound level and duration of exposure that contribute to individual susceptibility. External-ear amplification (EEA) from external-ear structures varies significantly due to ear size and shape, potentially influencing NIHL susceptibility. This study tested the hypothesis that EEA can be predicted using non-technical proxy measurements including pinna height (cm), body height (m), and earcanal volume (cm3). 158 participants (4-78 years) completed otoscopy, tympanometry, pinna measurements, body height measurements, and two EEA measurements: (1) total real-ear unaided gain (REUG) of the open ear and (2) real-ear to coupler difference (RECD), representing unaided gain from the earcanal. Participants' individual noise doses were compared in hypothetical exposures. REUG ranged from 5 to 19 dBA and was correlated with pinna height. High-REUG participants were estimated to accrue noise doses at least 5 times higher than low-REUG participants. RECD ranged from 7 to 24 dBA and was correlated with earcanal volume and body height. The results support the hypothesis that EEA measurement could significantly improve estimation of an individual's position along the NIHL risk spectrum. Non-technical proxy measurements of EEA (pinna height, body height, earcanal volume) were statistically significant but yielded high variability in individual EEA prediction.

Patterns of noise exposure and prevalence of hearing loss amongst Cape Town Minstrel Carnival musicians.

BackgroundCape Town Minstrel Carnival is one of the oldest and most authentic indigenous New Year’s customs in South Africa. Musicians who perform at this carnival are exposed to excessively loud music and therefore at a risk of acquiring noise-induced hearing loss (NIHL).ObjectivesThis study aimed to determine patterns of exposure to loud music and prevalence of hearing loss amongst Cape Town Minstrel Carnival musicians.MethodA descriptive, observational exploratory survey design was used and 43 participants (21 males and 22 females; mean age, 21 ± 9 years) took part in this study. Sound level measurements were conducted to assess musicians’ sound exposure during rehearsals and performances. All participants underwent the following audiological test battery at least 2 h before music exposure: Case history, otoscopic examination, tympanometry, pure tone audiometry and distortion products otoacoustic emission (DPOAE).ResultsAverage noise levels recorded were 86 dBA during rehearsals and 98.7 dBA at performances and average durations of exposure were 240 and 10 min at rehearsals and performances, respectively. One out of 43 (1/43) participants presented with sensorineural hearing loss. Audiometric results of the remaining participants were normal and did not show a pattern suggestive of NIHL. A high proportion of participants (21/43) reported experiencing tinnitus.ConclusionDespite being exposed to high levels of noise, there was a low prevalence of hearing loss amongst these musicians. However, a high proportion of them reported tinnitus, which could be an indication that they were at a high risk of NIHL from the music that they played.

Temporary threshold shift after noise exposure in hypobaric hypoxia at high altitude: results of the ADEMED expedition 2011

ObjectivesTo evaluate whether there is an increased risk for noise-induced hearing loss at high altitude rsp. in hypobaric hypoxia.MethodsThirteen volunteers got standard audiometry at 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, and 8000 Hz before and after 10 min of white noise at 90 dB. The system was calibrated for the respective altitude. Measurements were performed at Kathmandu (1400 m) and at Gorak Shep (5300 m) (Solo Khumbu/Nepal) after 10 days of acclimatization while on trek. Temporary threshold shift (TTS) was analyzed by descriptive statistics and by factor analysis.ResultsTTS is significantly more pronounced at high altitudes. Acclimatization does not provide any protection of the inner ear, although it increases arterial oxygen saturation.ConclusionThe thresholds beyond which noise protection is recommended (> 80 dB) or necessary (> 85 dB) are not sufficient at high altitudes. We suggest providing protective devices above an altitude of 1500 m (“ear threshold altitude”) when noise level is higher than 75 dB and using them definitively above 80 dB. This takes the individual reaction on hypobaric hypoxia at high altitude into account.

Genetic association study between TAB2 polymorphisms and noise-induced-hearing-loss in a Han Chinese population.

Noise-induced-hearing-loss(NIHL) is a common occupational disease caused by various environmental and biological factors. To investigate the association between TAB2 and the susceptibility of NIHL of people exposed to occupational environments, a genetic association study was performed on selected companies with 588 cases and 537 healthy control subjects. Five selected single nucleotide polymorphisms (SNPs) in TAB2,incoluding rs2744434, rs521845, rs652921, rs7896, rs9485372, were genotyped after a collection of DNA samples. Evident differences in participants between the case group and the control group reveals the result that people with the TAB2 has a high probability of getting NIHL. The results show that rs521845 is deeply associated with the risk of NIHL and is available for the diagnosis in the future.

Improving our understanding on non-occupational noise-induced hearing loss

Noise is among the most common occupational and non-occupational exposures globally. As a result, the public health burden of noise-induced hearing loss is high. Some estimates suggest that roughly 20% of all hearing loss cases result from occupational noise exposure. Occupational noise exposures have been extensively studied and regulated in many countries for decades, and as a result the risk of occupational noise-induced hearing loss associated with different exposure levels and durations has been modeled and quantified. However, non-occupational exposures have not been nearly as well-characterized, and the risk of non-occupational noise-induced hearing loss is not well understood. This presentation will describe a systematic review conducted to evaluate the risk of noise-induced hearing loss associated with non-occupational noise. The presentation will also discuss knowledge gaps in our understanding of non-occupational noise exposures, and the need for tools to allow individuals to evaluate their own exposures against recommended non-occupational noise exposure limits, and ideally to share these “citizen-science” data for aggregated analysis. This approach is now being utilized in the Apple Hearing Study, a partnership between Apple, Inc., and the University of Michigan. Details will be provided on the research approaches and some preliminary results from the Apple Hearing Study.

A functional SNP in miR-625-5p binding site of AKT2 3'UTR is associated with noise-induced hearing loss susceptibility in the Chinese population.

The purposes of the current study were to investigate the association of a few of single nucleotide polymorphisms (SNPs) within the AKT2 gene and noise-induced hearing loss (NIHL) susceptibility and explore the potential mechanism underlying NIHL. Three SNPs (rs2304186, rs41275750, and rs76524493) were genotyped in a Chinese population which consists of 690 NIHL patients and 650 normal hearing controls. Bioinformatic analysis was conducted to predict the potential miRNA-binding site of SNPs. Plasmid construction, cell transfection, and dual-luciferase reporter assay were performed to investigate the potential molecular mechanism of SNPs involving in NIHL. The results revealed that rs2304186 GT genotype (OR = 1.41; 95% CI = 1.09-1.83) and TT genotype (OR = 1.51; 95% CI = 1.08-2.10) imparted increased risk of NIHL, and the increased risk could also be found in a dominant model (OR = 1.44; 95% CI = 1.12-1.84). The stratification analysis showed that rs2304186 GT/TT conferred a higher risk for NIHL, especially in subgroups of male, age (35-45 and > 45 years), noise exposure time (> 16 years), and noise exposure level (≤ 85 and ≥ 92 dB), when GG genotype as a reference. Furthermore, the haplotype TCCTACT (rs2304186-rs41275750-rs76524493) was found to be significantly associated with a high risk of NIHL (OR = 1.19; 95% CI = 1.02-1.40). Functional experiments showed that rs2304186 G allele combined with hsa-miR-625-5p mimics could significantly decrease the luciferase activity compared with T allele, indicating that rs2304186 altered the binding affinity of hsa-miR-625-5p to SNP rs2304186 mutation region, thus directly targeting AKT2 gene. In conclusion, our study provides evidence for the first time that SNP rs2304186 of AKT2 3'UTR might affect NIHL susceptibility by altering the binding affinity of has-miR-625-5p to mutation region in an allele-specific manner and it may act as a potential biomarker of NIHL susceptibility.

Histone deacetylase 2 polymorphisms associated with noise-induced hearing loss in Chinese workers.

Noise-induced hearing loss (NIHL) is one of these hazards which has been the second most common sensorineural hearing loss. Single-nucleotide polymorphisms (SNPs) mainly refer to the polymorphism of DNA sequence caused by the variation at the genomic nucleotide level. The influence of histone deacetylase 2 (HDAC2) variants on the risk of NIHL has not been studied. This research explored the association between HDAC2 and the development of NIHL. A total of 1146 industrial workers from one textile factory in east China were recruited to perform a case-control study. Basic clinical data such sex, age, smoking, and drinking was obtained by questionnaires; pure-toneaudiometry (PTA) tests were conducted by specialist physicians. Then, we performed genotyping of five selected SNPs (rs10499080, rs2475631, rs2499618, rs6568819, and rs3757016) in the HDAC2 gene in 600 NIHL patients and 546 controls. Finally, the main influences of the SNPs and their interactions with NIHL were assessed. Under the recessive model, there were statistically significant differences in the genotype frequencies of rs10499080 between two groups, and the results showed that individuals with rs10499080 CC+CT had a lower risk of NIHL (OR = 0.597, 95%CI = 0.357-0.998). Meanwhile, the significant difference in the genotype distributions between cases and controls was found in rs10499080 in the group with noise exposure of ≤ 16 years. But the following haplotype analysis showed that no association between all haplotypes in the HDAC2 gene and NIHL was been found. The genetic polymorphisms rs10499080 and rs6568819 within HDAC2 gene have an association with risk of NIHL. Workers exposed to noise with HDAC2 have a lower risk of NIHL.

Role of CASP7 polymorphisms in noise-induced hearing loss risk in Han Chinese population

Genetic factors and gene-environment interaction may play an important role in the development of noise induced hearing loss (NIHL). 191 cases and 191 controls were selected by case–control study. Among them, case groups were screened from workers exposed to noise in binaural high-frequency hearing thresholds greater than 25 dB (A). Workers with hearing thresholds ≤ 25 dB (A) in any binaural frequency band were selected to the control group, based on matching factors such as age, exposure time to noise, and operating position. The blood samples from two groups of workers were subjected to DNA extraction and SNP sequencing of CASP3 and CASP7 genes using the polymerase chain reaction ligase detection reaction method. Conditional logistic regression correction was used to analyze the genetic variation associated with susceptibility to NIHL. There was an association between rs2227310 and rs4353229 of the CASP7 gene and the risk of NIHL. Compared with the GG genotype, the CC genotype of rs2227310 reduced the risk of NIHL. Compared with CC genotype, the TT genotype of rs4353229 reduced the risk of NIHL. Workers carrying the rs2227310GG and rs4353229CC genotype had an increased risk of NIHL compared to workers without any high-risk genotype. There were additive interaction and multiplication interaction between CASP7rs2227310 and CNE, and the same interaction between CASP7rs4353229 and CNE. The interaction between the CASP7 gene and CNE significantly increased the risk of NIHL. The genetic polymorphisms of CASP7rs2227310GG and CASP7rs4353229CC were associated with an increased risk of NIHL in Han Chinese population and have the potential to act as biomarkers for noise-exposed workers.