Newborn genetic screening for hearing impairment: a population-based longitudinal study

Genetic screening of newborns for deafness over 11 years in Beijing, China: More infants could benefit from an expanded program

Genetic screening of newborns for deafness plays an important role in elucidating the etiology of deafness, diagnosing it early, and intervening in it. Genetic screening of newborns has been conducted for 11 years in Beijing. It started with a chip to screen for 9 variants of 4 genes in 2012; the chip screened for 15 variants of those genes in 2018, and it now screens for 23 variants of those genes. In the current study, a comparative analysis of three screening protocols and follow-up for infants with pathogenic variants was performed. The rates of detection and hearing test results of infants with pathogenic variants were analyzed. Subjects were 493,821 infants born at 122 maternal and child care centers in Beijing from April 2012 to August 2023. Positivity increased from 4.599% for the chip to screen for 9 variants to 4.971% for the chip to screen for 15 variants, and further to 11.489% for the chip to screen for 23 variants. The carrier frequency of the GJB2 gene increased from 2.489% for the chip to screen for 9 variants and 2.422% for the chip to screen for 15 variants to 9.055% for the chip to screen for 23 variants. The carrier frequency of the SLC26A4 gene increased from 1.621% for the chip to screen for 9 variants to 2.015% for the chip to screen for 15 variants and then to 2.151% for the chip to screen for 23 variants. According to the chip to screen for 9 variants and the chip to screen for 15 variants, the most frequent mutant allele was c.235delC. According to the chip to screen for 23 variants, the most frequent mutant allele was c.109G>A. The chip to screen for 15 variants was used to screen 66.67% (14/21) of newborns with biallelic variants in the SLC26A4 gene for newly added mutations. The chip to screen for 23 variants was used to screen 92.98% (53/57) of newborns with biallelic variants in the GJB2 gene (52 cases were biallelic c.109G>A) and 25% (1/4) of newborns with biallelic variants in the SLC26A4 gene for newly added mutations. Among the infants with pathogenic variants (biallelic variants in GJB2 or SLC26A4), 20.66% (25/121) currently have normal hearing. In addition, 34.62% (9/26) of newborns who passed the hearing screening were diagnosed with hearing loss. Findings indicate that a growing number of newborns have benefited, and especially in the early identification of potential late-onset hearing loss, as the number of screening sites has increased. Conducting long-term audiological monitoring for biallelic variants in individuals with normal hearing is of paramount significance.

Newborn concurrent hearing and genetic screening for hearing impairment: A systematic review and meta‑analysis

Hearing loss is the most prevalent neurosensory disorder in humans, with significant implications for language, social and cognitive development if not diagnosed and treated early. The present systematic review and meta-analysis aimed to determine the rate of hearing screening pass and genetic screening failure [universal newborn hearing screening (UNHS) pass/genetic failure] and to investigate the advantages of combining newborn hearing and genetic screening for newborn hearing impairment. The PubMed, Embase and Cochrane databases were searched from inception to September 2023 to identify studies reporting the combination of neonatal hearing screening with genetic screening. Duplicate literature, unpublished literature, studies with incomplete data, animal experiments, literature reviews and systematic studies were excluded. All the data were processed by STATA15.1 statistical software. A total of nine cross-sectional studies were included in this meta-analysis. The sample sizes ranged from 1,716 to 180,469, and there were a total of 377,688 participants. The pooled results revealed that the prevalence of passing the UNHS while failing genetic screening was 0.31% (95% CI, 0.22-0.41%). The prevalence of UNHS pass and gap junction protein beta 2 and solute carrier family 26 member 4 variant screen failure was 0.01% (95% CI, 0.00-0.02%) and 0.00% (95% CI, 0.00%), respectively, while the prevalence of mitochondrially encoded 12S RRNA variant screening failure and UNHS pass was 0.21% (95% CI, 0.18-0.26%). Combined screening has a significant advantage over pure hearing screening, especially in terms of identifying newborns with mitochondrial gene mutations that render them sensitive to certain medications. In clinical practice, decision-makers can consider practical circumstances and leverage the benefits of combined newborn hearing and genetic screening for early diagnosis, early counseling, and early intervention in patients with hearing loss.

Implementing next-generation sequencing for diagnosis and management of hereditary hearing impairment: a comprehensive review

INTRODUCTION

Sensorineural hearing impairment (SNHI), a common childhood disorder with heterogeneous genetic causes, can lead to delayed language development and psychosocial problems. Next-generation sequencing (NGS) offers high-throughput screening and high-sensitivity detection of genetic etiologies of SNHI, enabling clinicians to make informed medical decisions, provide tailored treatments, and improve prognostic outcomes.

AREAS COVERED

This review covers the diverse etiologies of HHI and the utility of different NGS modalities (targeted sequencing and whole exome/genome sequencing), and includes HHI-related studies on newborn screening, genetic counseling, prognostic prediction, and personalized treatment. Challenges such as the trade-off between cost and diagnostic yield, detection of structural variants, and exploration of the non-coding genome are also highlighted.

EXPERT OPINION

In the current landscape of NGS-based diagnostics for HHI, there are both challenges (e.g. detection of structural variants and non-coding genome variants) and opportunities (e.g. the emergence of medical artificial intelligence tools). The authors advocate the use of technological advances such as long-read sequencing for structural variant detection, multi-omics analysis for non-coding variant exploration, and medical artificial intelligence for pathogenicity assessment and outcome prediction. By integrating these innovations into clinical practice, precision medicine in the diagnosis and management of HHI can be further improved.

Increased risk of hearing loss associated with MT-RNR1 gene mutations: a real-world investigation among Han Taiwanese Population

BACKGROUND

Previous studies have implicated inherited mutations in mitochondrial DNA (mtDNA) in sensorineural hearing loss (SNHL). However, the definitive association between mitochondrial 12S rRNA (MT-RNR1) variants and hearing loss in the population has not been well established, particularly in Asia. The objective of this retrospective cohort study was to assess the association between MT-RNR1 variants and the risk of SNHL in patients in Taiwan.

METHODS

The cohort included 306,068 participants from Taiwan between January 2003 and December 2020. Participants were classified based on genetic variants, particularly mitochondrial mutations (rs267606618, rs267606619, rs267606617). MT-RNR1 variant cases were matched 1:10 with non-mutant patients by age, gender, and visit year, excluding those with pre-existing hearing loss. The primary endpoint was SNHL, identified using specific ICD-TM codes with a 90% positive predictive value. Medication exposure history was determined via self-report or electronic medical records in the hospital. Cox proportional hazard regression models were used to assess the association between MT-RNR1 variants and hearing loss, adjusting for various covariates. Kaplan-Meier survival curves and log-rank tests compared hearing loss incidence between groups.

RESULTS

The mean age of the mtDNA variants group is 32.4 years, with a standard deviation of 19.2 years. The incidence density of hearing loss for the mutation group was 36.42 per 10,000 person-years (95% Confidence Interval [CI], 27.21-47.73), which was higher than the 23.77per 10,000 person-years (95% CI, 21.32-26.42) in the wild-type group (p = 0.0036). Additionally, diabetes mellitus was associated with an increased risk of developing SNHL in individuals with MT-RNR1 variants (adjusted hazard ratio = 1.76 [95% CI, 1.00-3.09], p < 0.05).

CONCLUSION

This study highlights the increased risk of hearing loss in patients carrying MT-RNR1 variants, particularly those with diabetes mellitus. Future research that integrates genetic and clinical data is crucial for developing more precise interventions to monitor and treat hearing loss in this vulnerable population.

Machine learning-based longitudinal prediction for GJB2-related sensorineural hearing loss

BACKGROUND

Recessive GJB2 variants, the most common genetic cause of hearing loss, may contribute to progressive sensorineural hearing loss (SNHL). The aim of this study is to build a realistic predictive model for GJB2-related SNHL using machine learning to enable personalized medical planning for timely intervention.

METHOD

Patients with SNHL with confirmed biallelic GJB2 variants in a nationwide cohort between 2005 and 2022 were included. Different data preprocessing protocols and computational algorithms were combined to construct a prediction model. We randomly divided the dataset into training, validation, and test sets at a ratio of 72:8:20, and repeated this process ten times to obtain an average result. The performance of the models was evaluated using the mean absolute error (MAE), which refers to the discrepancy between the predicted and actual hearing thresholds.

RESULTS

We enrolled 449 patients with 2184 audiograms available for deep learning analysis. SNHL progression was identified in all models and was independent of age, sex, and genotype. The average hearing progression rate was 0.61 dB HL per year. The best MAE for linear regression, multilayer perceptron, long short-term memory, and attention model were 4.42, 4.38, 4.34, and 4.76 dB HL, respectively. The long short-term memory model performed best with an average MAE of 4.34 dB HL and acceptable accuracy for up to 4 years.

CONCLUSIONS

We have developed a prognostic model that uses machine learning to approximate realistic hearing progression in GJB2-related SNHL, allowing for the design of individualized medical plans, such as recommending the optimal follow-up interval for this population.

Application of Genetic Information to Cochlear Implantation in Clinical Practice

Cochlear implantation is currently the treatment of choice for children with severe-to-profound sensorineural hearing impairment (SNHI). However, the outcomes with cochlear implant (CI) vary significantly among recipients. Genetic diagnosis offers direct clues regarding the pathogenesis of SNHI, which facilitates the development of personalized medicine for potential candidates for CI. In this article, I present a comprehensive overview of the usefulness of genetic information in clinical decision-making for CI. Genetically confirmed diagnosis enables clinicians to: 1) monitor the evolution of SNHI and determine the optimal surgical timing, 2) predict the potential benefits of CI in patients with identified genetic etiology, and 3) select CI devices/electrodes tailored to patients with specific genetic mutations.

Changing the standardised obstetric care by expanded carrier screening and counselling: a multicentre prospective cohort study

BACKGROUND

Expanded genetic screening before conception or during prenatal care can provide a more comprehensive evaluation of heritable fetal diseases. This study aimed to provide a large cohort to evaluate the significance of expanded carrier screening and to consolidate the role of expanded genetic screening in prenatal care.

METHODS

This multicentre, retrospective cohort study was conducted between 31 December 2019 and 21 July 2022. A screening panel containing 302 genes and next-generation sequencing were used for the evaluation. The patients were referred from obstetric clinics, infertility centres and medical centres. Genetic counsellors conducted consultation for at least 15 min before and after screening.

RESULTS

A total of 1587 patients were screened, and 653 pairs were identified. Among the couples who underwent the screening, 62 (9.49%) had pathogenic variants detected on the same genes. In total, 212 pathogenic genes were identified in this study. A total of 1173 participants carried at least one mutated gene, with a positive screening rate of 73.91%. Among the pathogenic variants that were screened, the gene encoding gap junction beta-2 (GJB2) exhibited the highest prevalence, amounting to 19.85%.

CONCLUSION

Next-generation sequencing carrier screening provided additional information that may alter prenatal obstetric care by 9.49%. Pan-ethnic genetic screening and counselling should be suggested for couples of fertile age.

Impact of Hearing Aids on Language Outcomes in Preschool Children With Mild Bilateral Hearing Loss

This study aimed to investigate the role of hearing aid (HA) usage in language outcomes among preschool children aged 3-5 years with mild bilateral hearing loss (MBHL). The data were retrieved from a total of 52 children with MBHL and 30 children with normal hearing (NH). The association between demographical, audiological factors and language outcomes was examined. Analyses of variance were conducted to compare the language abilities of HA users, non-HA users, and their NH peers. Furthermore, regression analyses were performed to identify significant predictors of language outcomes. Aided better ear pure-tone average (BEPTA) was significantly correlated with language comprehension scores. Among children with MBHL, those who used HA outperformed the ones who did not use HA across all linguistic domains. The language skills of children with MBHL were comparable to those of their peers with NH. The degree of improvement in audibility in terms of aided BEPTA was a significant predictor of language comprehension. It is noteworthy that 50% of the parents expressed reluctance regarding HA use for their children with MBHL. The findings highlight the positive impact of HA usage on language development in this population. Professionals may therefore consider HAs as a viable treatment option for children with MBHL, especially when there is a potential risk of language delay due to hearing loss. It was observed that 25% of the children with MBHL had late-onset hearing loss. Consequently, the implementation of preschool screening or a listening performance checklist is recommended to facilitate early detection.

Genetic Underpinnings and Audiological Characteristics in Children With Unilateral Sensorineural Hearing Loss

OBJECTIVE

Unilateral sensorineural hearing loss (USNHL) is a condition commonly encountered in otolaryngology clinics. However, its molecular pathogenesis remains unclear. This study aimed to investigate the genetic underpinnings of childhood USNHL and analyze the associated audiological features.

STUDY DESIGN

Retrospective analysis of a prospectively recruited cohort.

SETTING

Tertiary referral center.

METHODS

We enrolled 38 children with USNHL between January 1, 2018, and December 31, 2021, and performed physical, audiological, imaging, and congenital cytomegalovirus (cCMV) examinations as well as genetic testing using next-generation sequencing (NGS) targeting 30 deafness genes. The audiological results were compared across different etiologies.

RESULTS

Causative genetic variants were identified in 8 (21.1%) patients, including 5 with GJB2 variants, 2 with PAX3 variants, and 1 with the EDNRB variant. GJB2 variants were found to be associated with mild-to-moderate USNHL in various audiogram configurations, whereas PAX3 and EDNRB variants were associated with profound USNHL in flat audiogram configurations. In addition, whole-genome sequencing and extended NGS targeting 213 deafness genes were performed in 2 multiplex families compatible with autosomal recessive inheritance; yet no definite causative variants were identified. Cochlear nerve deficiency and cCMV infection were observed in 9 and 2, respectively, patients without definite genetic diagnoses.

CONCLUSION

Genetic underpinnings can contribute to approximately 20% of childhood USNHL, and different genotypes are associated with various audiological features. These findings highlight the utility of genetic examinations in guiding the diagnosis, counseling, and treatment of USNHL in children.

Genetic Factors Contribute to the Phenotypic Variability in GJB2-Related Hearing Impairment

Recessive variants in GJB2 are the most important genetic cause of sensorineural hearing impairment (SNHI) worldwide. Phenotypes vary significantly in GJB2-related SNHI, even in patients with identical variants. For instance, patients homozygous for the GJB2 p.V37I variant, which is highly prevalent in the Asian populations, usually present with mild-to-moderate SNHI; yet severe-to-profound SNHI is occasionally observed in approximately 10% of p.V37I homozygotes. To investigate the genomic underpinnings of the phenotypic variability, we performed next-generation sequencing of GJB2 and other deafness genes in 63 p.V37I homozygotes with extreme phenotypic severities. Additional pathogenic variants of other deafness genes were identified in five of the 35 patients with severe-to-profound SNHI. Furthermore, case-control association analyses were conducted for 30 unrelated p.V37I homozygotes with severe-to-profound SNHI against 28 p.V37I homozygotes with mild-to-moderate SNHI, and 120 population controls from the Taiwan Biobank. The severe-to-profound group exhibited a higher frequency of the crystallin lambda 1 (CRYL1) variant (rs14236), located upstream of GJB2, than the mild-to-moderate and Taiwan Biobank groups. Our results demonstrated that pathogenic variants in other deafness genes and a possible modifier, the CRYL1 rs14236 variant, may contribute to phenotypic variability in GJB2-realted SNHI, highlighting the importance of comprehensive genomic surveys to delineate the genotype-phenotype correlations.

Follow-up of infants with mild-to-moderate sensorineural hearing loss over three years

OBJECTIVE

To observe and analyse the hearing outcome in infants with mild-to-moderate sensorineural hearing loss (SNHL) who failed universal newborn hearing screening (UNHS).

METHODS

This retrospective cohort analysis included infants with mild-to-moderate SNHL and with complete etiological diagnosis and followed up over three years.

RESULTS

Out of 96 infants with mild-to-moderate SNHL 72 were stable (75%). Only one case was normal (1.04%), ten cases were improved (10.42%), and 13 were deteriorated (13.54%). The pathogenic mutation of GJB2 was the most common cause (50/96, 52.08%), and most of them were homozygous or complex heterozygous mutations of p.V37I (44/50, 88%). There were 11 cases (11.49%) with large vestibular aqueduct syndrome (LVAS) and nine cases (9.38%) with perinatal risk factors. Infants with GJB2 pathogenic mutation and those without certain etiology mostly had unchanged hearing levels, accounting for 84% (42/50) and 84.61% (22/26), respectively. Hearing deterioration in LVAS was associated with seven cases (63.64%). There was no difference in types of outcomes in perinatal risk factor infants, who were more likely to improve than the other groups, but there were three cases (33.3%) deteriorated to profound hearing loss. Comparison of outcomes of different etiologies showed statistically significant difference (Chi-square = 28.673, p = 0.000).

CONCLUSION

Normal and improved hearing in infants with mild-to-moderate SNHL was rare before the age of three, unlike in many previous studies, and appropriate intervention is recommended. However, intervention should be adjusted according to the hearing outcomes because of the possibility of improvement or deterioration. The etiological diagnosis of infants with mild-to-moderate SNHL would be helpful for predicting the outcome and managing intervention.

Analysis of GJB2 gene mutations spectrum and the characteristics of individuals with c.109G>A in Western Guangdong

BACKGROUND

GJB2 mutations are among the most important causes of deafness, and their prevalence varies greatly among different countries and ethnic groups. This study aimed to determine the pathogenic mutation spectrum of GJB2 in patients with nonsyndromic hearing loss (NSHL) in Western Guangdong and to explore the pathogenic characteristics of the c.109G>A locus.

METHODS

In total, 97 NSHL patients and 212 normal controls (NC) were included in this study. Genetic sequencing analyses were performed on GJB2.

RESULTS

In the NSHL group, the main pathogenic mutations in GJB2 were as follows: c.109G>A, c.235delC, and c.299_300delAT with allele frequencies of 9.28%, 4.12%, and 2.06%, respectively. c.109G>A was the most frequently detected pathogenic mutation in this region. In the NC group, the allele frequency of c.109G>A among 30-50 years old subjects was markedly lower than that among 0-30 years old subjects (5.31% vs. 11.11%, p < 0.05).

CONCLUSION

We found the pathogenic mutation spectrum of GJB2 in this region and showed that c.109G>A was the most common GJB2 mutation with unique characteristics, such as clinical phenotypic heterogeneity and delayed onset. Therefore, the c.109G>A mutation should be considered as an essential marker for routine genetic assessment of deafness, which can also be beneficial for preventing deafness.

Optimized concurrent hearing and genetic screening in Beijing, China: A cross-sectional study

Concurrent screening has been proven to provide a comprehensive approach for management of congenital deafness and prevention of ototoxicity. The SLC26A4 gene is associated with late-onset hearing loss and is of great clinical concern. For much earlier detection of newborns with deafness-causing mutations in the SLC26A4 gene, the Beijing Municipal Government launched a chip for optimized genetic screening of 15 variants of 4 genes causing deafness based on a chip to screen for 9 variants of 4 genes, and 6 variants of the SLC26A4 gene have now been added. To ascertain the advantage of a screening chip including 15 variants of 4 genes, the trends in concurrent hearing and genetic screening were analyzed in 2019 and 2020. Subjects were 76,460 newborns who underwent concurrent hearing and genetic screening at 24 maternal and child care centers in Beijing from January 2019 to December 2020. Hearing screening was conducted using transiently evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAE), or the automated auditory brainstem response (AABR). Dried blood spots were collected for genetic testing and 15 variants of 4 genes, namely GJB2, SLC26A4, mtDNA 12S rRNA, and GJB3, were screened for using a DNA microarray platform. The initial referral rate for hearing screening decreased from 3.60% (1,502/41,690) in 2019 to 3.23% (1,124/34,770) in 2020, and the total referral rate for hearing screening dropped form 0.57% (236/41,690) in 2019 to 0.54% (187/34,770) in 2020, indicating the reduced false positive rate of newborn hearing screening and policies to prevent hearing loss conducted by the Beijing Municipal Government have had a significant effect. Positivity according to genetic screening was similar in 2019 (4.970%, 2,072/41,690) and 2020 (4.863%,1,691/34,770), and the most frequent mutant alleles were c.235 del C in the GJB2 gene, followed by c.919-2 A > G in the SLC26A4 gene, and c.299 del AT in the GJB2 gene. In this cohort study, 71.43% (5/7) of newborns with 2 variants of the SLC26A4 gene were screened for newly added mutations, and 28.57% (2/7) of newborns with 2 variants of the SLC26A4 gene passed hearing screening, suggesting that a screening chip including 15 variants of 4 genes was superior at early detection of hearing loss, and especially in early identification of newborns with deafness-causing mutations in the SLC26A4 gene. These findings have clinical significance.

Clinical application value of expanded carrier screening in the population of childbearing age

OBJECTIVE

The objective of this study was to explore the clinical utility of the implementation of expanded carrier screening (ECS) in Chinese population of childbearing age.

MATERIALS AND METHODS

Based on capillary electrophoresis, a first-generation sequencing technology, a prospective screening study of carriers of 15 single-gene diseases was carried out in 327 subjects in Anhui Province, including 84 couples and 159 women of childbearing age, the disease carrier rate, types of screened pathogenic genes, and incidence of both partners carrying the same pathogenic genes were summarized and analyzed.

RESULTS

In 320 people with normal phenotypes who underwent ECS for 15 genetic diseases and 7 spouses who underwent targeted gene sequencing, 65 carriers of at least one disease were detected, with a total carrier rate of 20.31% (65/320). Among the 65 carriers, 81.54% (53/65) carried one genetic variant, 16.92% (11/65) carried two genetic variants, and 1.54% (1/65) carried three genetic variants. In this study, the three diseases with the highest carrier rates were hereditary deafness (8.13%, 26/320), Wilson's disease (4.06%, 13/320), and phenylketonuria (3.13%, 10/320). One high-risk couple (1.19%, 1/84) was detected.

CONCLUSIONS

It has certain clinical application value to implement ECS in the population of childbearing age in China.

The Frequency of Common Deafness-Associated Variants Among 3,555,336 Newborns in China and 141,456 Individuals Across Seven Populations Worldwide

OBJECTIVES

Genetic screening can benefit early detection and intervention for hearing loss. The frequency of common deafness-associated variants in general populations is highly important for genetic screening and genetic counseling tailored to different ethnic backgrounds. We aimed to analyze the frequency of common deafness-associated variants in a large population-based Chinese newborn cohort and to explore the population-specific features in diverse populations worldwide.

DESIGN

This population-based cohort study analyzed the frequency of common deafness-associated variants in 3,555,336 newborns in the Chinese Newborn Concurrent Hearing and Genetic Screening cohort. Participants were newborn infants born between January 2007 and September 2020. Limited genetic screening for 20 variants in 4 common deafness-associated genes and newborn hearing screening were offered concurrently to all newborns in the Chinese Newborn Concurrent Hearing and Genetic Screening cohort. Sequence information of 141,456 individuals was also analyzed from seven ethnic populations from the Genome Aggregation Database for 20 common deafness-related variants. Statistical analysis was performed using R.

RESULTS

A total of 3,555,326 Chinese neonates completed the Newborn Concurrent Hearing and Genetic Screening were included for analysis. We reported the distinct landscape of common deafness-associated variants in this large population-based cohort. We found that the carrier frequencies of GJB2 , SLC26A4 , GJB3 , and MT-RNR were 2.53%, 2.05%, 0.37%, and 0.25%, respectively. Furthermore, GJB2 c.235delC was the most common variant with an allele frequency of 0.99% in the Chinese newborn population. We also demonstrated nine East-Asia-enriched variants, one Ashkenazi Jewish-enriched variant, and one European/American-enriched variant for hearing loss.

CONCLUSIONS

We showed the distinct landscape of common deafness-associated variants in the Chinese newborn population and provided insights into population-specific features in diverse populations. These data can serve as a powerful resource for otolaryngologists and clinical geneticists to inform population-adjusted genetic screening programs for hearing loss.

Non-Syndromic Hearing Loss in a Romanian Population: Carrier Status and Frequent Variants in the GJB2 Gene

The genetic causes of autosomal recessive nonsyndromic hearing loss (ARNSHL) are heterogeneous and highly ethnic-specific. We describe GJB2 (connexin 26) variants and carrier frequencies as part of our study and summarize previously reported ones for the Romanian population. In total, 284 unrelated children with bilateral congenital NSHL were enrolled between 2009 and 2018 in northwestern Romania. A tiered diagnostic approach was used: all subjects were tested for c.35delG, c.71G>A and deletions in GJB6 (connexin 30) using PCR-based methods. Furthermore, 124 cases undiagnosed at this stage were analyzed by multiplex-ligation-dependent probe amplifications (MLPA), probe mix P163, and sequencing of GJB2 exon 2. Targeted allele-specific PCR/restriction fragment length polymorphism (RFLP) established definite ethio-pathogenical diagnosis for 72/284 (25.35%) of the cohort. Out of the 124 further analyzed, in 12 cases (9.67%), we found compound heterozygous point mutations in GJB2. We identified one case of deletion of exon 1 of the WFS1 (wolframin) gene. Carrier status evaluation used Illumina Infinium Global Screening Array (GSA) genotyping: the HINT cohort-416 individuals in northwest Romania, and the FUSE cohort-472 individuals in southwest Romania. GSA variants yielded a cumulated risk allele presence of 0.0284. A tiered diagnostic approach may be efficient in diagnosing ARNSHL. The summarized contributions to Romanian descriptive epidemiology of ARNSHL shows that pathogenic variants in the GJB2 gene are frequent among NSHL cases and have high carrier rates, especially for c.35delG and c.71G>A. These findings may serve in health strategy development.

Association Between Expanded Genomic Sequencing Combined With Hearing Screening and Detection of Hearing Loss Among Newborns in a Neonatal Intensive Care Unit

IMPORTANCE

Hearing loss is a global social burden. Early identification of hearing loss missed by newborn hearing screening tests in the neonatal intensive care unit is crucial.

OBJECTIVE

To assess the association between expanded genomic sequencing combined with hearing screening and detection of hearing loss as well as improvement in the neonatal intensive care unit.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was performed between August 8, 2016, and December 31, 2020, among 8078 newborns admitted to the neonatal intensive care unit of the Children's Hospital of Fudan University in Shanghai, China. Follow-up for hearing status was performed via telephone interviews between September 1 and November 30, 2021.

EXPOSURES

A hearing screening test and the expanded genomic sequencing targeting 2742 genes were administered to each patient. Those who failed the hearing screening test or had positive genetic findings were referred for diagnostic audiometry at a median of 3 months of age.

MAIN OUTCOMES AND MEASURES

The primary outcome was hearing loss missed by hearing screening test. Secondary outcomes were genetic findings and benefits associated with the expanded genomic sequencing for clinical management of patients in the neonatal intensive care unit.

RESULTS

Of 8078 patients (4666 boys [57.8%]; median age, 6.3 days [IQR, 3.0-12.0 days]), 52 of 240 (21.7%) received a diagnosis of hearing loss. Expanded genomic sequencing combined with hearing screening was associated with a 15.6% increase (7 of 45 patients) in cases of diagnosed hearing loss that were missed by hearing screening. Of the 52 patients with hearing loss, genetic factors were identified for 39 patients (75.0%); GJB2 and SLC26A4 were the most common genes identified. Patients with genetic findings experienced a more severe degree of hearing loss than those without genetic findings (21 profound, 4 severe, 7 moderate, and 7 mild vs 2 severe, 4 moderate, and 7 mild; P = .005), with more bilateral hearing loss (39 of 39 [100%] vs 9 of 13 [69.2%]; P = .003). Clinical management strategies were changed for patients who underwent genomic sequencing combined with hearing screening.

CONCLUSIONS AND RELEVANCE

This study suggests that expanded genomic sequencing combined with hearing screening may be effective at detecting hearing loss among patients in the neonatal intensive care unit.

A novel MPZL2 c.68delC variant is associated with progressive hearing loss in Chinese population and literature review

Objective

The aim of this study was to identify genetic etiology in two unrelated Chinese probands with progressive sensorineural hearing loss.

Methods

Two unrelated Chinese families were recruited. Genetic etiology was identified by targeted next-generation sequencing (NGS) and verified by Sanger sequencing. Hearing evaluations included pure tone audiometry, auditory brainstem response to clicks, and otoscopic examination. Medical history and computerized tomography scan of temporal bone were also collected. In addition, linear regression was used to summarize all of the reported cases and estimate the progression of hearing loss.

Results

A 28-year-old man with variant c.68delC had progressive, moderately severe hearing loss and a suspicious history of renal impairment. His hearing result was 63.75 dB HL. The other proband was the youngest patient with MPZL2-related hearing loss reported so far in the literature (genotype: c.220C>T homozygote). Her hearing result by click-ABR was 25 dB nHL at 3 months of age, and deteriorated to 40 dB nHL at 15 months. Behavioral audiometry identified a hearing loss of 26.25 dB HL. In summarizing all of the reported cases, using linear regression, MPZL2-related hearing loss may deteriorate by 0.59 dB HL per year, and different MPZL2 variants may lead to different rates of progression.

Conclusion

In this study, we first identified two unrelated patients with MPZL2-related hearing loss in Chinese population, and a novel variant c.68delC. Our results expanded the mutation spectrum of deafness genes. Further studies are required to clarify the genotype-phenotype correlation and the progression of MPZL2-related hearing loss.

The Burden and Benefits of Knowledge: Ethical Considerations Surrounding Population-Based Newborn Genome Screening for Hearing

Recent advances in genomic sequencing technologies have expanded practitioners' utilization of genetic information in a timely and efficient manner for an accurate diagnosis. With an ever-increasing resource of genomic data from progress in the interpretation of genome sequences, clinicians face decisions about how and when genomic information should be presented to families, and at what potential expense. Presently, there is limited knowledge or experience in establishing the value of implementing genome sequencing into newborn screening. Herein we provide insight into the complexities and the burden and benefits of knowledge resulting from genome sequencing of newborns.

Biallelic p.V37I variant in GJB2 is associated with increasing incidence of hearing loss with age

PURPOSE

This study aimed to quantitatively assess the incidence of hearing loss in relation to age in individuals with biallelic p.V37I variant in GJB2.

METHODS

Population screening of the biallelic p.V37I variant was performed in 30,122 individuals aged between 0 and 97 years in Shanghai. Hearing thresholds of the biallelic p.V37I individuals and the controls were determined by click auditory brainstem response or pure tone audiometry.

RESULTS

Biallelic p.V37I was detected in 0.528% (159/30,122) of the subjects. Of the biallelic p.V37I newborns, 43.91% (18/41) passed their distortion-product otoacoustic emissions-based newborn hearing screening or had hearing thresholds lower than 20 decible above normal hearing level. The older newborns had elevated hearing thresholds, with increasing incidence of 9.52%, 23.08%, 59.38%, and 80.00% for moderate or higher grade of hearing loss in age groups of 7 to 15 years, 20 to 40 years, 40 to 60 years, and 60 to 85 years, respectively. Their hearing deteriorated at a rate of 0.40 dB hearing level per year on average; males were more susceptible, and deterioration occurred preferentially at higher sound frequencies.

CONCLUSION

The biallelic p.V37I variant is associated with steadily progressive hearing loss with increasing incidence over the course of life. Most of the biallelic p.V37I individuals may develop significant hearing loss in adulthood and, can benefit from early diagnosis and intervention through wide-spread genetic screening.

Application of a next-generation sequencing (NGS) panel in newborn screening efficiently identifies inborn disorders of neonates

Background

Newborn screening (NBS) has been implemented for neonatal inborn disorders using various technology platforms, but false-positive and false-negative results are still common. In addition, target diseases of NBS are limited by suitable biomarkers. Here we sought to assess the feasibility of further improving the screening using next-generation sequencing technology.

Methods

We designed a newborn genetic sequencing (NBGS) panel based on multiplex PCR and next generation sequencing to analyze 134 genes of 74 inborn disorders, that were validated in 287 samples with previously known mutations. A retrospective cohort of 4986 newborns was analyzed and compared with the biochemical results to evaluate the performance of this panel.

Results

The accuracy of the panel was 99.65% with all samples, and 154 mutations from 287 samples were 100% detected. In 4986 newborns, a total of 113 newborns were detected with biallelic or hemizygous mutations, of which 36 newborns were positive for the same disorder by both NBGS and conventional NBS (C-NBS) and 77 individuals were NBGS positive/C-NBS negative. Importantly, 4 of the 77 newborns were diagnosed currently including 1 newborn with methylmalonic acidemia, 1 newborn with primary systemic carnitine deficiency and 2 newborns with Wilson’s disease. A total of 1326 newborns were found to be carriers with an overall carrier rate of 26.6%.

Conclusion

Analysis based on next generation sequencing could effectively identify neonates affected with more congenital disorders. Combined with C-NBS, this approach may improve the early and accurate identification of neonates with inborn disorders. Our study lays the foundation for prospective studies and for implementing NGS-based analysis in NBS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02231-x.

Genetics of Childhood Hearing Loss

Compelling evidence indicates that some newborns harboring genetic variants associated with hearing loss might not be identified by current physiologic newborn hearing screening (NBHS) rendering current NBHS protocols suboptimal. Incorporating genomic sequencing into NBHS would improve clinical diagnosis and decrease time to early intervention efforts.

Assessment of Hearing Screening Combined With Limited and Expanded Genetic Screening for Newborns in Nantong, China

IMPORTANCE

Early identification and intervention for newborns with hearing loss (HL) may lead to improved physiological and social-emotional outcomes. The current newborn hearing screening is generally beneficial but improvements can be made.

OBJECTIVE

To assess feasibility and evaluate utility of a modified genetic and hearing screening program for newborn infants.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study used a 4-stage genetic and hearing screening program at 6 local hospitals in Nantong city, China. Participants were newborn infants born between January 2016 and June 2020 from the Han population. Statistical analysis was performed from April 1 to May 1, 2021.

EXPOSURES

Limited genetic screening for 15 variants in 4 common HL-associated genes and newborn hearing screening (NHS) were offered concurrently to all newborns. Hearing rescreening and/or diagnostic tests were provided for infants with evidence of HL on NHS or genetic variants on screening. Expanded genetic tests for a broader range of genes were targeted to infants with HL with negative results of limited genetic tests.

MAIN OUTCOMES AND MEASURES

The detection capability for infants with hearing impairment who passed conventional hearing screening, as well as infants with normal hearing at risk of late-onset HL due to genetic susceptibility.

RESULTS

Among a total of 35 930 infants, 32 512 infants completed the follow-up and were included for analysis. Among the infants included in the analysis, all were from the Han population in China and 52.3% (16 988) were male. The modified genetic and hearing screening program revealed 142 cases of HL and 1299 cases of genetic variation. The limited genetic screening helped identify 31 infants who passed newborn hearing screening, reducing time for diagnosis and intervention; 425 infants with normal hearing with pathogenic SLC26A4 variation and 92 infants with MT-RNR1 variation were at risk for enlarged vestibular aqueduct and aminoglycoside-induced ototoxicity respectively, indicating early aversive or preventive management.

CONCLUSIONS AND RELEVANCE

This study found that performing modified genetic and hearing screening in newborns was feasible and provides evidence that the program could identify additional subgroups of infants who need early intervention. These findings suggest an advantage for universal adoption of such a practice.

Machine learning-based genetic diagnosis models for hereditary hearing loss by the GJB2, SLC26A4 and MT-RNR1 variants

Background

Hereditary hearing loss (HHL) is the most common sensory deficit, which highly afflicts humans. With gene sequencing technology development, more variants will be identified and support genetic diagnoses, which is difficult for human experts to diagnose. This study aims to develop a machine learning-based genetic diagnosis model of HHL-related variants of GJB2, SLC26A4 and MT-RNR1.

Methods

This case-control study included 1898 subjects, among which 1354 were HHL patients and 544 were carriers. Risk assessment models were established based on variants at 144 sites in three genes related to HHL by building six machine learning (ML) models. We compared the ML models with the genetic risk score (GRS) and expert interpretation (EI) to verify the clinical performance.

Findings

Among the six ML models, the support vector machine (SVM) showed the best performance. For the prediction of HHL-related gene sites in subjects with variants, the area under the receiver operating characteristic (AUC) of the SVM model was 0.803 (0.680–0.814) in the 10-fold stratified cross-validation and 0.751 (0.635–0.779) in external validation. The predicted results were better than both EI and GRS. Furthermore, 11 sites were identified as the smallest feature set that can be accurately predicted.

Interpretation

The developed SVM model has great potential to be an efficient and effective tool for HHL prediction when high throughput sequencing data are available.

A multiplex PCR amplicon sequencing assay to screen genetic hearing loss variants in newborns

BACKGROUND

Congenital hearing loss is one of the most common birth defects. Early identification and management play a crucial role in improving patients' communication and language acquisition. Previous studies demonstrated that genetic screening complements newborn hearing screening in clinical settings.

METHODS

We developed a multiplex PCR amplicon sequencing assay to sequence the full coding region of the GJB2 gene, the most pathogenic variants of the SLC26A4 gene, and hotspot variants in the MT-RNR1 gene. The sensitivity, specificity, and reliability were validated via samples with known genotypes. Finally, a pilot study was performed on 300 anonymous dried blood samples.

RESULTS

Of 103 samples with known genotypes, the multiplex PCR amplicon sequencing assay accurately identified all the variants, demonstrating a 100% sensitivity and specificity. The consistency is high in the analysis of the test-retest reliability and internal consistency reliability. In the pilot study, 12.3% (37/300) of the newborns were found to carry at least one pathogenic variant, including 24, 10, and 3 from the GJB2, SLC26A4, and MT-RNR1 gene, respectively. With an allele frequency of 2.2%, the NM_004004.6(GJB2):c.109G>A was the most prevalent variant in the study population.

CONCLUSION

The multiplex PCR amplicon sequencing assay is an accurate and reliable test to detect hearing loss variants in the GJB2, SLC26A4, and MT-RNR1 genes. It can be used to screen genetic hearing loss in newborns.

[Genotype and clinical phenotype analysis of 42 patients with delayed nonsyndromic hearing loss]

Objective:The aim of this study is to analyze the mutation characteristics of GJB2 and SLC26A4 gene in patients with delayed non-syndromic hearing loss, which is beneficial to the early detection and intervention of delayed deafness. Methods:Sanger sequencing technology was used to detect two common genes in 139 patients with non-syndromic deafness, six hot spot mutations in GJB2 gene and SLC26A4 gene, and single heterozygous mutations found in GJB2 gene and SLC26A4 gene were detected by whole exome sequencing. Results:Among the 25 patients with deafness caused by GJB2 gene mutation, 12 of them passed universal newborn hearing screening and then developed delayed extremely severe hearing loss. The onset time of hearing loss was 6-48 months. All the genotypes were homozygous or compound heterozygous mutation of c. 235delC, especially genotype of GJB2 c. 235delC homozygous and c. 235delC/c. 299-300 delAT compound heterozygous mutations, and the CT manifestations were normal. Among the 42 patients with deafness caused by SLC26A4 gene mutation, 30 of them passed universal newborn hearing screening and developed delayed deafness. The onset time of hearing loss was three months to ten years old. Among them, the genotypes of 21 patients were compound heterozygous mutation, and 9 patients were homozygous mutation of c. 919-2A>G, especially genotypes were SLC26A4 c. 919-2A>G/c. 665G>T and c. 919-2A>G /c. 2027T>A compound heterozygous mutation. The CT findings of 19 cases showed single enlarged vestibular aqueduct, and 11 cases showed enlarged vestibular aqueduct with Mondini malformation. Conclusion:For the children who have passed universal newborn hearing screening, the genotypes detected are GJB2 c. 235delC homozygous, SLC26A4 c. 919-2A>G homozygous or compound heterozygous mutations, especially genotypes GJB2 c. 235delC homozygous, c. 235delC/c. 299-300delAT compound heterozygous mutations and SLC26A4 c. 919-2A>G/c. 665G>T and c. 919-2A>G/c. 2027T>A compound heterozygous mutation. Attention should be paid to the hearing problems of children all the time, and the possibility of delayed deafness in the future should be considered.

Concurrent Newborn Hearing and Genetic Screening in a Multi-Ethnic Population in South China

Hearing loss is a common sensory deficit in humans with intricate genomic landscape and mutational signature. Approximately 1-3 out of 1,000 newborns have hearing loss and up to 60% of these cases have a genetic etiology. In this study, we conducted the concurrent newborn hearing and genetic screening in 20 mutations (18 pathogenic variants in GJB2, SLC26A4, and MT-RNR1 and 2 uncertain clinical significance variants in GJB3) for 9,506 normal newborns (4,977 [52.4%] males) from 22 ethnic population in South China. A total of 1,079 (11.4%) newborns failed to pass the initial hearing screening; 160 (1.7%) infants failed to pass the re-screening, and 135 (1.4%) infants presented the diagnostic hearing loss. For the genetic screening, 220 (2.3%) newborns who presented at least one of the screened mutations were more likely to fail the hearing screening and have diagnostic hearing loss than mutation-negative newborns. In comparison to the differences of distribution of mutations, we did not identify any significant difference in the prevalence of screened mutations between Han group (n = 5,265) and Zhuang group (n = 3,464), despite the lack of number of minority ethnic groups. Studies including larger number of minority ethnic populations are needed in the future.

GJB2 mutation spectrum in the Taiwanese population and genotype-phenotype comparisons in patients with hearing loss carrying GJB2 c.109G>A and c.235delC mutations

Hearing loss, the most common sensory abnormality, is caused by the death of or damage to inner ear hair cells. Genetic mutations are the main cause of hearing loss. We used nex-generation sequencing data released by the Taiwan Biobank to investigate the GJB2 mutation spectrum in 1517 patients. We compared hearing function in Taiwanese patients with nonsyndromic hearing loss (NSHL) caused by the two most common GJB2 mutations c.109G>A (p.V37I) and c.235delC. We extracted DNA from the oral mucosa of patients with NSHL and performed Sanger sequencing to confirm the genotype. Of 240 patients with NSHL, we identified 25 with GJB2 c.109G>A and 9 with GJB2 c.235delC mutations, after excluding patients aged >10 years, in whom hearing loss may have been caused due to age-related degeneration. We investigated genotype-phenotype correlations in patients harboring GJB2 c.109G>A and c.235delC mutations. Furthermore, we described the GJB2 mutation spectrum in the Taiwanese population and identified the role of homozygous and heterozygous GJB2 mutations associated with hearing phenotypes in patients with NSHL. Thus, our study provides insights into the complexity of GJB2 genetics. Our data indicate that GJB2 c.109G>A heterozygotes had poorer hearing than did homozygotes. The mechanism underlying the more severe phenotype in heterozygotes and whether the phenotype is caused by GJB2 heterozygotes or compound heterozygotes warrant future investigation.

Etiology of Prelingual Hearing Loss in the Universal Newborn Hearing Screening Era: A Scoping Review

OBJECTIVE

To conduct a scoping review on etiologic investigation of prelingual hearing loss among children <2 years of age in the era of universal newborn hearing screening (UNHS).

DATA SOURCES

PubMed, Embase, PsycInfo, CINAHL, and Cochrane Library databases.

REVIEW METHODS

We searched for articles published from January 1, 1998, to February 19, 2020. We reviewed studies that (1) included children identified with either congenital or delayed-onset hearing loss before 2 years of age among cohorts who had undergone UNHS and (2) investigated ≥1 etiologies of hearing loss. We defined hearing loss as congenital when confirmed after UNHS failure and as delayed onset when diagnosed after ≥1 assessments with normal hearing.

RESULTS

Among 2069 unique citations, 115 studies met criteria for full-text assessment, and 20 met our inclusion criteria. Six studies tested children diagnosed with hearing loss for genetic etiology, 9 for congenital cytomegalovirus (CMV) infection, and 5 for both. Among 1787 children with congenital hearing loss and etiologic investigation, 933 (52.2%) were tested for genetic mutations and 1021 (57.1%) for congenital CMV infection. The proportion of congenital hearing loss cases attributable to genetic etiology ranged between 7.7% and 83.3% and to congenital CMV infection between 0.0% and 32.0%.

CONCLUSION

Data are lacking on the identification and etiology of delayed-onset hearing loss in children <2 years of age in the UNHS era. The proportion of congenital hearing loss cases attributable to genetic etiologies and congenital CMV infection appears to vary widely.

Deafness Gene Mutations in Newborns in the Foshan Area of South China With Bloodspot-Based Genetic Screening Tests

Purpose The aim of this study was to determine the rate of deafness gene mutations in the Foshan area of South China. Method We enrolled the infants delivered in Foshan Maternity and Children's Healthcare Hospital. Deafness gene mutation was detected by HibriMax method. Our study tested 47,538 newborns within 3 days after birth, including 13 sites in four genes: GJB2 (c.35 del G, c.176 del 16, c.235 del C, c.299 del AT, c.155 del TCTG), GJB3 (c.583 C>T), SLC26A4 (c.2168 A>G, c.919-2 A>G, c.1299 C>T), and mtDNA 12S rRNA (m.1555 A>G, m.1494 C>T, m.12201 T>C, m.7445 A>G). The birth condition of infants was collected, including sex, low or high birth weight, twins, and premature delivery. Results In a total of 47,538 newborns, 1,415 were positively identified with deafness gene mutations. The total rate of the deafness gene mutation was 2.976%. The carrier rates of GJB2 (c.35 del G, c.176 del 16, c.235 del C, c.299 del AT, c.155 del TCTG), GJB3 (c.583 C>T), SLC26A4 (c.2168 A>G, c.919-2 A>G, c.1299 C>T), and mtDNA 12S rRNA (m.1555 A>G, m.1494 C>T, m.12201 T>C, m.7445 A>G) mutations were 0.000%, 0.048%, 1.422%, 0.185%, 0.000%, 0.076%, 0.116%, 0.755%, 0.160%, 0.187%, 0.021%, 0.000%, and 0.006%, respectively. Conclusions Our study showed that the c.235 del C GJB2 mutation was the leading deafness-related mutation in the Foshan area of South China. Deafness gene mutations screening in newborns detected by bloodspot-based genetic screening tests can help the diagnosis of newborn congenital hearing loss.

Development of in-house genetic screening for pediatric hearing loss

OBJECTIVES

To evaluate the efficiency of in-house genetic testing for mutations causing the most common types of inherited, nonsyndromic, sensorineural hearing loss (SNHL).

METHODS

Retrospective cohort study of 200 patients at a single, pediatric medical center with suspected or confirmed hearing loss who underwent either send out vs in-house genetic testing for mutations in GJB2/GJB6, SLC26A4, and MTRNR1. Primary outcome measure was the difference in mean turnaround time for send-out vs in-house genetic testing. Additional outcomes included associations between audiometric findings and genetic test results.

RESULTS

One hundred four send-out tests were performed between October 2010 and June 2014, and 100 in-house tests were performed between November 2014 and November 2016. The mean turnaround time for send-out testing was 53.7 days. The mean turnaround time for in-house testing was 18.9 days. This difference was statistically significant (P < .001). The largest component of turnaround time was the amount of time elapsed between receipt of specimen in the lab and final test result. These intervals were 47.0 and 18.3 days for send-out and in-house tests, respectively. Notably, the longest turnaround time for in-house testing (43 days) was less than the average turnaround time for send-out testing. In addition, we identified two simple audiometric parameters (ie, bilateral newborn hearing screen referral and audiometry showing symmetric SNHL) that may increase diagnostic yield of genetic testing.

CONCLUSIONS

The development of in-house genetic testing programs for inherited SNHL can significantly reduce testing turnaround times. Newborn hearing screening and audiometry results can help clinicians identify patients most likely to benefit from genetic testing.

LEVEL OF EVIDENCE

IV.

[Analysis of genotypes and hearing phenotypes of mutation infants with deafness]

Objective:The aim of this study is to explore the genotype and hearing phenotype of deaf infants with mutation of GJB2 gene. Method:Subjects were 121 infants with GJB2 gene mutations who were treated in the Children's Hearing Diagnosis Center of Beijing Tongren hospital. All subjects were accepted to undertake the universal newborns hearing screening（UNHS） and series of objective audiometry, including auditory brainstem response, distortion product otoacoustic emission, auditory steady-state response and other audiological tests. All subjects were screened for nine pathogenic variants in four genes or all exons of the GJB2 gene, and then were diagnosed as infants with GJB2 gene mutations. Initially, analyzing their genotypes and hearing phenotypes generally. Then, the subjects were divided into two groups according to the genotypes: T/T group（truncated/truncated mutations, 89 cases） and T/NT group（truncated/non-truncated mutations, 32 cases）. Chi-square test was used to analyze the results of UNHS, hearing degree, audiogram patterns and symmetry/asymmetry of binaural hearing phenotype. Eventually, analyzing the results of UNHS. Result:The most common truncated mutation was c.235delC（64.88%, 157/242） and the most common non-truncated mutation was c.109G>A（11.16%, 27/242）. The homozygous mutation of c.235delC/c.235delC was the dominant in T/T group（38.84%, 47/121）, and the compound heterozygous mutation of c.235delC/c.109G>A was the dominant in T/NT group（18.18%, 22/121）. 81.82%（99/121） of subjects failed in UNHS, including 74.38%（90/121） with bilateral reference, 7.44%（9/121） with a single pass. The refer rate of UNHS of group T/T and T/NT were 86.52%（77/89） and 68.75%, respectively. There was a statistically significant difference between the two groups（P<0.05）. 85.95%（104/121） of subjects were diagnosed as hearing loss and 14.05%（17/121） of subjects were diagnosed as normal hearing. The degree of hearing loss: profound, severe, moderate and mild were 31.40%（38/121）, 19.01%（23/121）, 24.79%（30/121） and 10.74%（13/121）, respectively. There was no subjects with normal hearing in T/T group and individuals with severe and profound hearing loss accounted for the highest proportion（65.17%, 58/89）, while in T/NT group, normal hearing accounted for 53.13%（17/32） and mild and moderate hearing loss accounted for the highest proportion（37.5%, 12/32）. There was statistically significant difference between the two groups（P<0.05）. Of 104 patients（208 ears） with hearing loss, the audiogram patterns: flat, descending, ascending, residual, Valley and other types were 49.03%（102/208）, 12.02%（25/208）, 8.65%（18/208）, 7.69%（16/204）, 3.36%（7/204） and 19.23%（40/204）, respectively. The two most common types in T/T group were flat（47.19%, 84/178） and other types（20.22%, 36/178）, while in T/NT group were flat（60.00%, 18/30） and ascending（20.00%, 6/30）. There was statistically significant difference between the two groups（P<0.05）. There were 50 cases（48.07%） with symmetrical hearing phenotype and 54 cases（51.93%） with asymmetrical hearing phenotype. Asymmetry was predominant in T/T group（53.93%, 48/89）, and symmetry was predominant in T/NT group（60.00%, 9/15）. There was no statistically significant difference between the two groups（P>0.05）. Conclusion:In this study, c.235delC/c.235delC homozygous mutation was dominant in T/T group and c.235delC/c.109G>A heterozygous mutation was dominant in T/NT Group. The hearing phenotypes in T/T group were mostly bilateral asymmetric severe hearing loss, and those in T/NT Group were bilateral symmetric mild to moderate hearing loss, special attention should be paid to the audiological characteristics of different genotypes.

Concurrent hearing and genetic screening in a general newborn population

Newborn hearing screening is not designed to detect delayed-onset prelingual hearing loss or aminoglycoside-antibiotic-induced ototoxicity. Cases with severe to profound hearing loss have been reported to have been missed by newborn hearing screens. The aim of this study was to evaluate the efficacy of concurrent hearing and genetic screening in the general population and demonstrate its benefits in practice. Enrolled newborns received concurrent hearing and genetic screens between September 1, 2015 and January 31, 2018. Of the 239,636 eligible infants (median age, 19 months), 548 (0.23%) had prelingual hearing loss. Genetic screening identified 14 hearing loss patients with positive genotypes and 27 patients with inconclusive genotypes who had passed the hearing screens. In addition, the genetic screen identified 0.23% (570/239,636) of the newborns and their family members as at-risk for ototoxicity, which is undetectable by hearing screens. In conclusion, genetic screening complements newborn hearing screening by improving the detection of infants at risk of hereditary hearing loss and ototoxicity, and by informing genotype-based clinical management for affected infants and their family members. Our findings suggest that the practice should be further validated in other populations and rigorous cost-effectiveness analyses are warranted.

A pediatric perspective on genomics and prevention in the twenty-first century

We present evidence from diverse disciplines and populations to identify the current and emerging role of genomics in prevention from both medical and public health perspectives as well as key challenges and potential untoward consequences of increasing the role of genomics in these endeavors. We begin by comparing screening in healthy populations (newborn screening), with testing in symptomatic populations, which may incidentally identify secondary findings and at-risk relatives. Emerging evidence suggests that variants in genes subject to the reporting of secondary findings are more common than expected in patients who otherwise would not meet the criteria for testing and population testing for variants in these genes may more precisely identify discrete populations to target for various prevention strategies starting in childhood. Conversely, despite its theoretical promise, recent studies attempting to demonstrate benefits of next-generation sequencing for newborn screening have instead demonstrated numerous barriers and pitfalls to this approach. We also examine the special cases of pharmacogenomics and polygenic risk scores as examples of ways genomics can contribute to prevention amongst a broader population than that affected by rare Mendelian disease. We conclude with unresolved questions which will benefit from future investigations of the role of genomics in disease prevention.

Suspension array-based deafness genetic screening in 53,033 Chinese newborns identifies high prevalence of 109 G>A in GJB2

OBJECTIVES

More than 50% of congenital hearing loss is attributed to genetic factors. Data of gene mutation associated with hearing loss from large population studies in Chinese population are scarce. In this study, we conducted a comprehensive newborn genetic screening in China to establish the carrier frequency and mutation spectrum of deafness-associated genes.

METHODS

A total of 53,033 newborns were screened for hearing defects associated mutations. Twenty hot spot mutations in GJB2, GJB3, SLC26A4 and mitochondria12S rRNA were examined using suspension array analysis.

RESULTS

14,185 newborns (26.75%) were identified with at least one mutated allele. 872 (1.64%) neonates carried homozygous mutations including 112 (0.21%) mitochondrial DNA homoplasmy, 228 (0.43%) were compound heterozygotes, and 11,985 (22.59%) were heterozygotes including 11 (0.02%) mitochondrial DNA heteroplasmy. Top five mutations included 109 G > A, 235 delC, 299-300 delAT in GJB2, IVS7-2 A > G in SLC26A4 and 1555 A > G in mitochondria12S rRNA. Notably, a total of 10,995 neonates (20.73%) carried 109 G > A in GJB2. Moreover, the allele frequencies of 109 G > A were detected 11.61% in Guangdong, 10.44% in Sichuan and 2.88% in Shandong, respectively, a significant difference in prevalence among these geographic regions (p<0.01). In addition, the high frequency of 109 G > A in GJB2 was confirmed by a TaqMan probe-based qPCR assay. Very recently, the ClinGen Hearing Loss Expert Panel reached a consensus and confirmed its pathogenic role in hearing impairment.

CONCLUSION

We delineated the mutation profile of common deafness-causing genes in the Chinese population and highlighted the high prevalence of 109 G > A pathogenic mutation. Our study may facilitate early diagnosis/intervention and genetic counseling for hearing impairment in clinical practice.

Consensus interpretation of the p.Met34Thr and p.Val37Ile variants in GJB2 by the ClinGen Hearing Loss Expert Panel

PURPOSE

Pathogenic variants in GJB2 are the most common cause of autosomal recessive sensorineural hearing loss. The classification of c.101T>C/p.Met34Thr and c.109G>A/p.Val37Ile in GJB2 are controversial. Therefore, an expert consensus is required for the interpretation of these two variants.

METHODS

The ClinGen Hearing Loss Expert Panel collected published data and shared unpublished information from contributing laboratories and clinics regarding the two variants. Functional, computational, allelic, and segregation data were also obtained. Case-control statistical analyses were performed.

RESULTS

The panel reviewed the synthesized information, and classified the p.Met34Thr and p.Val37Ile variants utilizing professional variant interpretation guidelines and professional judgment. We found that p.Met34Thr and p.Val37Ile are significantly overrepresented in hearing loss patients, compared with population controls. Individuals homozygous or compound heterozygous for p.Met34Thr or p.Val37Ile typically manifest mild to moderate hearing loss. Several other types of evidence also support pathogenic roles for these two variants.

CONCLUSION

Resolving controversies in variant classification requires coordinated effort among a panel of international multi-institutional experts to share data, standardize classification guidelines, review evidence, and reach a consensus. We concluded that p.Met34Thr and p.Val37Ile variants in GJB2 are pathogenic for autosomal recessive nonsyndromic hearing loss with variable expressivity and incomplete penetrance.

Concurrent Hearing and Genetic Screening of 180,469 Neonates with Follow-up in Beijing, China

Concurrent hearing and genetic screening of newborns is expected to play important roles not only in early detection and diagnosis of congenital deafness, which triggers intervention, but also in predicting late-onset and progressive hearing loss and identifying individuals who are at risk of drug-induced HL. Concurrent hearing and genetic screening in the whole newborn population in Beijing was launched in January 2012. This study included 180,469 infants born in Beijing between April 2013 and March 2014, with last follow-up on February 24, 2018. Hearing screening was performed using transiently evoked otoacoustic emission (TEOAE) and automated auditory brainstem response (AABR). For genetic testing, dried blood spots were collected and nine variants in four genes, GJB2, SLC26A4, mtDNA 12S rRNA, and GJB3, were screened using a DNA microarray platform. Of the 180,469 infants, 1,915 (1.061%) were referred bilaterally or unilaterally for hearing screening; 8,136 (4.508%) were positive for genetic screening (heterozygote, homozygote, or compound heterozygote and mtDNA homoplasmy or heteroplasmy), among whom 7,896 (4.375%) passed hearing screening. Forty (0.022%) infants carried two variants in GJB2 or SLC26A4 (homozygote or compound heterozygote) and 10 of those infants passed newborn hearing screening. In total, 409 (0.227%) infants carried the mtDNA 12S rRNA variant (m.1555A>G or m.1494C>T), and 405 of them passed newborn hearing screening. In this cohort study, 25% of infants with pathogenic combinations of GJB2 or SLC26A4 variants and 99% of infants with an m.1555A>G or m.1494C>T variant passed routine newborn hearing screening, indicating that concurrent screening provides a more comprehensive approach for management of congenital deafness and prevention of ototoxicity.

Genetic Epidemiology and Clinical Features of Hereditary Hearing Impairment in the Taiwanese Population

Hereditary hearing impairment (HHI) is a common but heterogeneous clinical entity caused by mutations in a plethora of deafness genes. Research over the past few decades has shown that the genetic epidemiology of HHI varies significantly across populations. In this study, we used different genetic examination strategies to address the genetic causes of HHI in a large Taiwanese cohort composed of >5000 hearing-impaired families. We also analyzed the clinical features associated with specific genetic mutations. Our results demonstrated that next-generation sequencing-based examination strategies could achieve genetic diagnosis in approximately half of the families. Common deafness-associated genes in the Taiwanese patients assessed, in the order of prevalence, included GJB2, SLC26A4, OTOF, MYO15A, and MTRNR1, which were similar to those found in other populations. However, the Taiwanese patients had some unique mutations in these genes. These findings may have important clinical implications for refining molecular diagnostics, facilitating genetic counseling, and enabling precision medicine for the management of HHI.

Nationwide population genetic screening improves outcomes of newborn screening for hearing loss in China

PURPOSE

The benefits of concurrent newborn hearing and genetic screening have not been statistically proven due to limited sample sizes and outcome data. To fill this gap, we analyzed outcomes of newborns with genetic screening results.

METHODS

Newborns in China were screened for 20 hearing-loss-related genetic variants from 2012 to 2017. Genetic results were categorized as positive, at-risk, inconclusive, or negative. Hearing screening results, risk factors, and up-to-date hearing status were followed up via phone interviews.

RESULTS

Following up 12,778 of 1.2 million genetically screened newborns revealed a higher rate of hearing loss by three months of age among referrals from the initial hearing screening (60% vs. 5.0%, P < 0.001) and a lower rate of lost-to-follow-up/documentation (5% vs. 22%, P < 0.001) in the positive group than in the inconclusive group. Importantly, genetic screening detected 13% more hearing-impaired infants than hearing screening alone and identified 2,638 (0.23% of total) newborns predisposed to preventable ototoxicity undetectable by hearing screening.

CONCLUSION

Incorporating genetic screening improves the effectiveness of newborn hearing screening programs by elucidating etiologies, discerning high-risk subgroups for vigilant management, identifying additional children who may benefit from early intervention, and informing at-risk newborns and their maternal relatives of increased susceptibility to ototoxicity.

Genetic screening as an adjunct to universal newborn hearing screening: literature review and implications for non-congenital pre-lingual hearing loss

Objective: Universal newborn hearing screening (UNHS) uses otoacoustic emissions testing (OAE) and auditory brainstem response testing (ABR) to screen all newborn infants for hearing loss (HL), but may not identify infants with mild HL at birth or delayed onset HL. The purpose of this review is to examine the role of genetic screening to diagnose children with pre-lingual HL that is not detected at birth by determining the rate of children who pass UNHS but have a positive genetic screening. This includes a summary of the current UNHS and its limitations and a review of genetic mutations and screening technologies used to detect patients with an increased risk of undiagnosed pre-lingual HL.Design: Literature review of studies that compare UNHS with concurrent genetic screening.Study sample: Infants and children with HLResults: Sixteen studies were included encompassing 137,895 infants. Pathogenic mutations were detected in 8.66% of patients. In total, 545 patients passed the UNHS but had a positive genetic screening. The average percentage of patients who passed UNHS but had a positive genetic screening was 1.4%.Conclusions: This review demonstrates the positive impact of concurrent genetic screening with UNHS to identify patients with pre-lingual HL.

Panel-based NGS reveals disease-causing mutations in hearing loss patients using BGISEQ-500 platform

Hearing loss is a highly heterogeneous disease presented with various phenotypes. Genetic testing of disease-causing mutations plays an important role in precise diagnosis and fertility guidance of heredity hearing loss. Here we reported an effective method employing target enrichment and BGISEQ-500 platform to detect clinically relevant alterations for heredity hearing patients in a single assay.In this study, we designed an array based chip, containing 127 genes related to hearing loss. Then we conducted targeted next-generation sequencing toward 58 patients to make a precise diagnosis using BGISEQ-500 platform.We successfully detected disease-causing mutations in 77.59% (45/58) of the patients with hearing loss. Finally, a total of 62 disease-causing mutations were identified, including 31 missense, 17 Indel, 11 splicing, 2 synonymous, and 1 copy number variant. 58.06% (36/62) of which has never been reported before.To our knowledge, this is the first report using BGISEQ-500 platform to investigate both syndromic and nonsyndromic hearing loss in the Chinese population. The results showed that this method can greatly assist and enhance hearing loss diagnosis and improve molecular diagnostics outcome.

Genetic screening involving 101 hot spots for neonates not passing newborn hearing screening and those random recruited in Dongguan

In order to investigate essential molecular causes for hearing loss and mutation frequency of deafness-related genes, 1315 newborns who did not pass the Newborn Hearing Screening (NHS) (audio-no-pass) and 1000 random-selected infants were subjected to detection for 101 hotspot mutations in 18 common deafness-related genes. Totally, 23 alleles of 7 deafness genes were detected out. Significant difference (χ² = 25.320, p = 0.000) existed in causative mutation frequency between audio-no-pass group (81/1315, 6.160%) and random-selected cohort (18/1000, 1.80%). Of the genes detected out, GJB2 gene mutation was with significant difference (χ² = 75.132, p = 0.000) between audio-no-pass group (417/1315, 31.711%) and random-selected cohort (159/1000, 15.900%); c.109G > A was the most common allele, as well as the only one with significantly different allele frequency (χ² = 79.327, p = 0.000) between audio-no-pass group (392/1315, 16.84%) and random-selected cohort (140/1000, 7.55%), which suggested c.109G > A mutation was critical for newborns' hearing loss. This study performed detection for such a large scale of deafness-associated genes and for the first time compared mutations between audio-no-pass and random-recruited neonates, which not only provided more reliable DNA diagnosis result for medical practioners and enhanced clinical care for the newborns, but gave more accurate estimation for mutation frequency.

Mutation analysis of common deafness genes among 1,201 patients with non-syndromic hearing loss in Shanxi Province

Background

Hearing impairment is one of most frequent birth defects, which affects nearly 1 in every 1,000 live births. However, the molecular etiology of non‐syndromic deafness in China is not well studied. Here, we have investigated the presence of mutations in three genes commonly mutated in non‐syndromic deafness patients in Shanxi Province, which has the highest frequency of birth defects in China.

Methods

In total, 1,201 unrelated non‐syndromic deafness patients and 300 healthy individuals were enrolled. The hearing ability was confirmed by audiologic evaluation. Three major deafness‐related genes (GJB2, SLC26A4 (PDS), and mtDNA 12S rRNA) of all individuals enrolled were analyzed by Sanger sequencing.

Results

The results showed that GJB2 mutations accounted for 21.23% (255/1,201) in the patient group, with c.235delC, a hotspot mutation, accounting for 10.99% (132/1,201). Moreover, 11 new GJB2 mutations were identified. SLC26A4 mutations accounted for 9.33% (112/1,201) in the patient group, with IVS7‐2A>G as the most prevalent mutation accounting for 4.75% (57/1,201). In addition, 15 patients (1.25%) were found to carry mtDNA 12S rRNA c.1555A>G mutation, while only two cases had the mtDNA 12S rRNA c.1494C>T.

Conclusion

In our research, it was found that c.235delC in GJB2 and c.919‐2A>G (IVS7‐2A>G) in SLC26A4 were the highest frequency pathogenic variants in Shanxi Province. Taken together, our data will enrich the database of deafness mutations and will help clinical diagnosis, treatment, and genetic counseling of hearing impairment.

Unique spectra of deafness-associated mutations in Mongolians provide insights into the genetic relationships among Eurasian populations

Genetic factors are an important cause of idiopathic sensorineural hearing impairment (SNHI). From the epidemiological perspective, mutations of three deafness genes: GJB2, SLC26A4, and MT-RNR1, are much more prevalent than those of other genes worldwide. However, mutation spectra of common deafness genes differ remarkably across different populations. Here, we performed comprehensive genetic examination and haplotype analyses in 188 unrelated Mongolian families with idiopathic SNHI, and compared their mutation spectra and haplotypes to those of other European and Asian cohorts. We confirmed genetic diagnoses in 18 (9.6%) of the 188 families, including 13 with bi-allelic GJB2 mutations, three with bi-allelic SLC26A4 mutations, and two with homoplasmic MT-RNR1 m.1555A>G mutation. Moreover, mono-allelic mutations were identified in 17 families (9.0%), including 14 with mono-allelic GJB2 mutations and three with mono-allelic SLC26A4 mutations. Interestingly, three GJB2 mutations prevalent in other populations, including c.35delG in Caucasians, c.235delC in East Asians, and c.-23+1G>A in Southwest and South Asians, were simultaneously detected in Mongolian patients. Haplotype analyses further confirmed founder effects for each of the three mutations, indicating that each mutation derived from its ancestral origin independently. By demonstrating the unique spectra of deafness-associated mutations, our findings may have important clinical and scientific implications for refining the molecular diagnostics of SNHI in Mongolian patients, and for elucidating the genetic relationships among Eurasian populations.

Generation of induced pluripotent stem cells from a patient with hearing loss carrying GJB2 p.V37I mutation

Recessive mutations in the GJB2 gene are the most common genetic cause of hearing loss in humans. By using the Sendai-virus delivery system, we generated induced pluripotent stem cells (iPSCs) from the peripheral blood mononuclear cells of a female patient with the p.V37I (c.109G > A) mutation, a GJB2 mutation highly prevalent in the Asian population. The resulting iPSCs had a normal karyotype. The iPSCs also showed pluripotency, as confirmed by immunofluorescence staining, and differentiated into the three germ layers in vivo. This cellular model will provide a useful platform for investigating the pathogenic mechanisms of deafness related to GJB2 mutations.

Children with GJB2 gene mutations have various audiological phenotypes

The current study retrospectively investigated variations in audiological phenotypes in children with GJB2 gene mutations. Subjects were 128 infants and young children who were seen as outpatients by Otology at Beijing Tongren Hospital from 2012 to 2018. Of the 128 subjects, 99 had biallelic truncating (T/T) mutations and 29 had truncating/nontruncating (T/NT) mutations. Genotypes, results of universal newborn hearing screening (UNHS), and the degree and symmetry of hearing loss were examined in the two groups. Twenty-two subjects (20.37%, 22/128) passed UNHS, including 13 children with T/T mutations and 9 with T/NT mutations. Of the 128 subjects, 22 had normal hearing, 2 had unilateral hearing loss, and 115 had bilateral hearing loss. Severe-to-profound hearing loss was the most prevalent phenotype in children with T/T mutations (73.23%), while normal hearing was prevalent in children with T/NT mutations (41.38%). Symmetrical hearing loss was the main phenotype in both groups, and the number of subjects with symmetrical hearing loss did not differ significantly between the two groups. Therefore, children with GJB2 gene mutations have phenotypic variability in terms of their results of UNHS and their degree and symmetry of hearing loss. Subjects with T/NT mutations of the GJB2 gene were more likely to pass UNHS and had milder hearing loss compared to those with T/T mutations. Symmetrical hearing loss was the main phenotype in the two groups, but 36.53% of children had bilateral asymmetric hearing loss. Parents of all subjects with sensorineural hearing loss were informed that their children may have a GJB2 mutation.

Concurrent Hearing, Genetic, and Cytomegalovirus Screening in Newborns, Taiwan

OBJECTIVE

To evaluate the feasibility and potential benefits of incorporating genetic and cytomegalovirus (CMV) screenings into the current newborn hearing screening (NHS) programs.

STUDY DESIGN

Newborns were recruited prospectively from a tertiary hospital and a maternity clinic between May 2016 and December 2016 and were subjected to hearing screening, CMV screening, and genetic screening for 4 common mutations in deafness genes (p.V37I and c.235delC of GJB2 gene, c.919-2A>G of SLC26A4 gene, and the mitochondrial m.1555A>G). Infants with homozygous nuclear mutations or homoplasmic/heteroplasmic mitochondrial mutation (referred to as "conclusively positive genotypes") and those who tested positive for CMV received diagnostic audiologic evaluations.

RESULTS

Of the total 1716 newborns enrolled, we identified 20 (1.2%) newborns with conclusively positive genotypes on genetic screening, comprising 15 newborns (0.9%) with GJB2 p.V37I/p.V37I and 5 newborns (0.3%) with m.1555A>G. Three (0.2%) newborns tested positive on CMV screening. Twelve of the 20 newborns (60%) with conclusively positive genotypes and all 3 newborns who tested positive for CMV (100%) passed NHS at birth. Diagnostic audiologic evaluations conducted at 3 months confirmed hearing impairment in 6 of the 20 infants (30%) with conclusively positive genotypes.

CONCLUSIONS

This study confirms the feasibility of performing hearing, genetic, and CMV screenings concurrently in newborns and provides evidence that the incorporation of these screening tests could potentially identify an additional subgroup of infants with impaired hearing that might not be detected by the NHS programs.

Association between the p.V37I variant of GJB2 and hearing loss: a pedigree and meta-analysis

Pathogenic variants in the gap junction protein beta-2 (GJB2) gene are the most common cause of hearing loss. Of these, the p.V37I variant of GJB2 has a high allele frequency (up to 10%) in East Asians. Characterization of the phenotypic spectrum associated with p.V37I, as well as the role of this variant in the onset of hearing loss could have a remarkable effect on future diagnostic strategies. Here, we performed a pedigree analysis of unrelated families exhibiting various hearing phenotypes, and then conducted a meta-analysis to comprehensively assess the association between the p.V37I and the risk of hearing loss. Pedigree analyses showed that both homozygous p.V37I variants, as well as compound heterozygous p.V37I with other GJB2 pathogenic variants, contributed to various phenotypes of hearing loss. Meanwhile, meta-analysis demonstrated that, compared with those in the wild type group, both p.V37I homozygotes and compound heterozygous p.V37I variants were at significantly higher risk of developing hearing loss (odds ratios = 7.14 and 3.63; 95% confidence intervals = 3.01-16.95 and 1.38–9.54, respectively). Conversely, heterozygous p.V37I variants alone did not increase the risk of hearing loss. Given the high allele carriage rate of p.V37I (up to 10%) within the general population, our work not only provides information that might influence future genetic screening policies, but also offers insight into clinical risk evaluation and genetic counseling regarding hearing loss.

Large scale newborn deafness genetic screening of 142,417 neonates in Wuhan, China

Almost one third of the three million people in China suffering severe deafness are children, and 50% of these cases are believed to have genetic components to their etiology. Newborn hearing genetic screening can complement Universal Neonatal Hearing Screening for the diagnosis of congenital hearing loss as well as identifying children at risk for late-onset and progressive hearing impairment. The aim of this joint academic and Ministry of Health project was to prototype a cost effective newborn genetic screen in a community health setting on a city-wide level, and to ascertain the prevalence of variation at loci that have been associated with non-syndromic hearing loss. With the participation of 143 local hospitals in the city of Wuhan, China we screened 142,417 neonates born between May 2014 and Dec. 2015. The variants GJB2 c.235delC, SLC26A4 c.919-2A>G, and mitochondrial variants m.1555A>G and m.1494C>T were assayed using real time PCR. Newborns found to carry a variant were re-assayed by sequencing in duplicate. Within a subset of 707 newborns we assayed using real-time PCR and ARMS-PCR to compare cost, sensitivity and operating procedure. The most frequent hearing loss associated allele detected in this population was the 235delC variant in GJB2 gene. In total, 4289 (3.01%) newborns were found to carry at least one allele of either GJB2 c.235delC, SLC26A4 c.919-2A>G or two assayed MT-RNR1 variants. There was complete accordance between the real-time PCR and the ARMS PCR, though the real-time PCR had a much lower failure rate. Real-time PCR had a lower cost and operating time than ARMS PCR. Ongoing collaboration with the participating hospitals will determine the specificity and sensitivity of the association of the variants with hearing loss at birth and arising in early childhood, allowing an estimation of the benefits of newborn hearing genetic screening in a large-scale community setting.