Late-onset Hearing Loss Research Articles

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.

Rare KCNQ4 variants found in public databases underlie impaired channel activity that may contribute to hearing impairment

KCNQ4 is frequently mutated in autosomal dominant non-syndromic hearing loss (NSHL), a typically late-onset, initially high-frequency loss that progresses over time (DFNA2). Most KCNQ4 mutations linked to hearing loss are clustered around the pore region of the protein and lead to loss of KCNQ4-mediated potassium currents. To understand the contribution of KCNQ4 variants to NSHL, we surveyed public databases and found 17 loss-of-function and six missense KCNQ4 variants affecting amino acids around the pore region. The missense variants have not been reported as pathogenic and are present at a low frequency (minor allele frequency < 0.0005) in the population. We examined the functional impact of these variants, which, interestingly, induced a reduction in potassium channel activity without altering expression or trafficking of the channel protein, being functionally similar to DFNA2-associated KCNQ4 mutations. Therefore, these variants may be risk factors for late-onset hearing loss, and individuals harboring any one of these variants may develop hearing loss during adulthood. Reduced channel activity could be rescued by KCNQ activators, suggesting the possibility of medical intervention. These findings indicate that KCNQ4 variants may contribute more to late-onset NSHL than expected, and therefore, genetic screening for this gene is important for the prevention and treatment of NSHL.

Risk factors for hearing loss in children: a systematic literature review and meta-analysis protocol

BackgroundHearing loss in newborns and children is a public health concern, due to high prevalence and negative effects on their development. Early detection and intervention of childhood hearing loss may mitigate these negative effects. Population-based newborn hearing screening programs have been established worldwide to identify children at risk for congenital hearing loss and to follow children at risk for late onset or progressive hearing loss. This article presents the protocol for a systematic review that aims to review the risk factors associated with permanent hearing loss in children, including congenital, early, or late onset. Risk factors associated with progressive hearing loss will be investigated as a secondary aim.MethodsScientific literature from the following databases will be investigated: MEDLINE, Ovid MEDLINE(R) Daily and Ovid MEDLINE(R), Embase, and CINAHL. The primary outcome is a permanent bilateral or unilateral hearing loss with congenital onset or onset during childhood (birth to 18 years). The secondary outcome is progressive hearing loss. Studies must report data on risk factors associated with permanent hearing loss; risk factors may be present at birth or later and result in immediate or delayed hearing loss. Randomized controlled trials, quasi-experimental studies, nonrandomized comparative and non-comparative studies, and case series will be included. The risk of bias will be assessed using the Qualitative Assessment Tool for Quantitative Studies (McMaster University). If aggregation of data is possible for a subsection of studies, we will pool data using meta-analysis techniques. If aggregation of data is not possible, a qualitative synthesis will be presented. We will assess the quality and strength of the overall body of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). The systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations.DiscussionThe resulting information will inform the update of a provincial audiological surveillance protocol for the Ontario Infant Hearing Program and will be applicable to early hearing detection and intervention (EHDI) programs worldwide.Systematic review registrationWe have registered the protocol in the International Prospective Register of Systematic Reviews (PROSPERO), registration number CRD42018104121.

The effects of age and sex on the detection of pure tones by adult CBA/CaJ mice (Mus musculus).

Age-related hearing loss (ARHL) is a neurodegenerative disorder characterized by a gradual decrease in hearing sensitivity. Previous electrophysiological and behavioral studies have demonstrated that the CBA/CaJ mouse strain is an appropriate model for the late-onset hearing loss found in humans. However, few studies have characterized hearing in these mice behaviorally using longitudinal methodologies. The goal of this research was to utilize a longitudinal design and operant conditioning procedures with positive reinforcement to construct audiograms and temporal integration functions in aging CBA/CaJ mice. In the first experiment, thresholds were collected for 8, 16, 24, 42, and 64kHz pure tones in 30 male and 35 female CBA/CaJ mice. Similar to humans, mice had higher thresholds for high frequency tones than for low frequency pure tones across the lifespan. Female mice had better hearing acuity than males after 645days of age. In the second experiment, temporal integration functions were constructed for 18 male and 18 female mice for 16 and 64kHz tones varying in duration. Mice showed an increase in thresholds for tones shorter than 200ms, reaching peak performance at shorter durations than other rodent species. Overall, CBA/CaJ mice experience ARHL for pure tones of different frequencies and durations, making them a good model for studies on hearing loss. These findings highlight the importance of using a wide range of stimuli and a longitudinal design when comparing presbycusis across different species.

Novel EYA4 variant in Slovak family with late onset autosomal dominant hearing loss: a case report

BackgroundProgressive bilateral sensorineural deafness in postlingual period may be linked to many different etiologies including genetic factors. Identification of the exact deafness cause may, therefore, be quite challenging. Here we present a family with late-onset hearing loss as an autosomal dominant trait caused by a novel EYA4 mutation.Case presentationForty-four years old female proband clinically investigated for progressive hearing loss and occasional dizziness with positive family history for deafness was subject to molecular-genetic testing. Patient’s DNA sample was analyzed by whole exome sequencing. We identified a novel missense variant c.804G > C located at the last base pair of exon 10 in EYA4. Candidate variant was confirmed by Sanger sequencing in the proband and her family members. In silico prediction tools and co-segregation analysis were used to indicate pathogenicity of the identified variant. To confirm our hypothesis, we performed minigene assay to demonstrate if the transcript of exon 10 in EYA4 is present. We provide evidence that this mutation in vitro compromises donor site functionality and causes exon 10 skipping and frameshift that most likely results in nonsense-mediated mRNA decay. The onset of moderate to severe hearing loss in the family ranged from 10 to 40 years. The normal cardiac phenotype was confirmed by ECG and echocardiography.ConclusionsWe identified a novel EYA4 mutation associated with adult-onset autosomal dominant sensorineural hearing loss. This report extends the knowledge of spectrum of EYA4 mutations and demonstrates the pathogenicity of a variant affecting specific position in the gene. A comprehensive review of known EYA4 mutations is also given and their impact on cardiac phenotype is discussed. Our findings highlight the importance of genetic testing and complex clinical assessment in patients with familial progressive hearing loss.

A humanized mouse model, demonstrating progressive hearing loss caused by MYO6 p.C442Y, is inherited in a semi-dominant pattern

Myosin VI is an actin-associated molecular motor vital for auditory and vestibular function. It is encoded by MYO6 located on chromosome 6q13 in human. Pathogenic variants in MYO6 have been associated with both dominant and recessive forms of hearing loss. However, the molecular mechanisms remain unclear. We established a humanized knock-in mouse model, Myo6-C442Y, to mimic the p.C442Y missense variant identified in human patients with autosomal dominant nonsyndromic hearing loss designated as DFNA22. We characterized hearing and inner ear morphologies of Myo6-C442Y and wild-type control mice. We found that both homozygous and heterozygous Myo6-C442Y mice exhibited hearing loss from three weeks after birth that rapidly progressed to profound deafness by six to nine weeks of age. The hearing loss corresponded to the degeneration of hair cells in the organ of Corti. We also observed disorganized stereocilia with irregular morphological features by immunohistochemistry and scanning electron microscopy. Additionally, hearing loss and inner-ear morphological anomalies were more pronounced and deteriorated more drastically in homozygous than in heterozygous Myo6-C442Y mice, indicating a semi-dominant inheritance pattern. Heterozygous Myo6-C442Y mice recapitulated the progressive postlingual sensorineural deafness in human, thus providing a useful model for elucidating the role myosin VI plays in the mammalian auditory system. Furthermore, the late-onset hearing loss of this mouse model may provide a therapeutic window for the emerging gene therapy, a promising strategy to treat certain forms of genetic deafness.

LittlEARS auditory questionnaire as an infant hearing screening in Germany after the newborn hearing screening

Objective: To investigate the feasibility of using the LittlEARS® Auditory Questionnaire (LEAQ®) as part of the infant hearing screening programme in Germany.Design: LEAQ®s were distributed to 47 paediatric practices and were completed by the parents/guardians of the infants (aged between 9-14 months) involved in the study (= LEAQ® screening). The infants who failed the LEAQ® screening were invited to a LEAQ rescreening. Infants who failed the LEAQ® rescreening were sent to a paediatric ENT specialist. After 3 years, a follow-up was performed on two groups: the first group comprised infants who failed the LEAQ screening; the second group (control group) comprised 200 infants who passed the LEAQ screening.Study Sample: 5316 questionnaires were returned.Results: Six infants with permanent hearing loss were identified using the LEAQ® as a screening tool.Conclusions: An infant hearing screening using the LEAQ® is easily implementable in paediatric practices and may be a good alternative in countries where no objective screening instruments are available. The LEAQ® was suitable for monitoring hearing development in infants in general and could help to identify a late-onset or progressive hearing loss in infants.

LMO7 deficiency reveals the significance of the cuticular plate for hearing function

Sensory hair cells, the mechanoreceptors of the auditory and vestibular systems, harbor two specialized elaborations of the apical surface, the hair bundle and the cuticular plate. In contrast to the extensively studied mechanosensory hair bundle, the cuticular plate is not as well understood. It is believed to provide a rigid foundation for stereocilia motion, but specifics about its function, especially the significance of its integrity for long-term maintenance of hair cell mechanotransduction, are not known. We discovered that a hair cell protein called LIM only protein 7 (LMO7) is specifically localized in the cuticular plate and the cell junction. Lmo7 KO mice suffer multiple cuticular plate deficiencies, including reduced filamentous actin density and abnormal stereociliar rootlets. In addition to the cuticular plate defects, older Lmo7 KO mice develop abnormalities in inner hair cell stereocilia. Together, these defects affect cochlear tuning and sensitivity and give rise to late-onset progressive hearing loss.

A systematic review of hearing and vestibular function in carriers of the Pro51Ser mutation in the COCH gene.

The Pro51Ser (P51S) COCH mutation is characterized by a late-onset bilateral sensorineural hearing loss (SNHL) and progressive vestibular deterioration. The aim of this study was to carry out a systematic review of all reported hearing and vestibular function data in P51S COCH mutation carriers and its correlation with age. Scientific databases including Medline, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, ISI Web of Knowledge, and Web of Science were searched to accumulate information about hearing outcome and vestibular function. Eleven genotype-phenotype correlation studies of the P51S COCH variant were identified and analyzed. The SNHL starts at the age of 32.8years. The Annual Threshold Deterioration is 3 decibel hearing loss (dB HL) per year (1-24 dB HL/year). Profound SNHL was observed at 76years on average (60-84years). 136 individual vestibular measurements were collected from 86 carriers. The onset of the vestibular dysfunction was estimated around 34years (34-40years), and vestibular deterioration rates were higher than those of the SNHL, with complete bilateral loss observed between 49 and 60years. Both audiometric and vestibular data were processed with much different methodologies and pre-symptomatic P51S carriers were systematically underrepresented. Further delineation of this correlation would benefit cross-sectional and longitudinal study involving all (pre-symptomatic and symptomatic) P51S carriers.

The spatial distribution pattern of Connexin26 expression in supporting cells and its role in outer hair cell survival

Mutations in the GJB2 gene (which encodes Connexin26 (Cx26)) account for about a quarter of all cases of non-syndromic deafness. Previous studies have indicated that knockout (KO) of Gjb2 gene during early postnatal days can cause outer hair cell (OHC) loss in mouse models. However, the postnatal spatial distribution pattern of Cx26 in different types of supporting cells (SCs) and the role of such distributions for the survival of OHCs is still obscure. In this study, the spatial distribution patterns of Cx26 in SCs were observed, and based on these observations different spatial Cx26-null mouse models were established in order to determine the effect of changes in the spatial distribution of Cx26 in SCs on the survival of OHCs. At postnatal day (P)3, unlike the synchronous expression of Cx26 along both longitudinal and radial boundaries of most types of SCs, Cx26 expression was primarily observed along the longitudinal boundaries of rows of Deiter’s cells (DCs). From P5 to P7, radial expression of Cx26 was gradually observed between adjacent rows of DCs. When Gjb2 gene was knocked out at random in different types of SCs, about 40% of the total DCs lost Cx26 expression and these Cx26-null DCs were distributed randomly in all three rows of DCs. The mice in this randomly Cx26-null group showed normal hearing and no significant OHC loss. When using a longitudinal KO pattern to induce knockout of Gjb2 gene specifically in the third row of DCs, about 33% of the total DCs lost Cx26 expression in this specific longitudinally Cx26-null group. The mice in this group showed late-onset hearing loss and significant OHC loss, however, the morphology of corresponding DCs was slightly altered. In both experimental groups, no substantial DC loss was observed. These results indicate that longitudinal Cx26-based channels are predominant in DCs during P3–P5. The Cx26 expression along rows of DCs might play a key role in the survival of OHCs, but this longitudinal KO pattern in DCs has a limited effect on DC survival or on its postnatal development.

Whole-exome sequencing identifies two novel mutations in KCNQ4 in individuals with nonsyndromic hearing loss

Mutations in potassium voltage-gated channel subfamily Q member 4 (KCNQ4) are etiologically linked to a type of nonsyndromic hearing loss, deafness nonsyndromic autosomal dominant 2 (DFNA2). We performed whole-exome sequencing for 98 families with hearing loss and found mutations in KCNQ4 in five families. In this study, we characterized two novel mutations in KCNQ4: a missense mutation (c.796G>T; p.Asp266Tyr) and an in-frame deletion mutation (c.259_267del; p.Val87_Asn89del). p.Asp266Tyr located in the channel pore region resulted in early onset and moderate hearing loss, whereas p.Val87_Asn89del located in the N-terminal cytoplasmic region resulted in late onset and high frequency-specific hearing loss. When heterologously expressed in HEK 293 T cells, both mutant proteins did not show defects in protein trafficking to the plasma membrane or in interactions with wild-type (WT) KCNQ4 channels. Patch-clamp analysis demonstrated that both p.Asp266Tyr and p.Val87_Asn89del mutant channels lost conductance and were completely unresponsive to KCNQ activators, such as retigabine, zinc pyrithione, and ML213. Channels assembled from WT-p.Asp266Tyr concatemers, like those from WT-WT concatemers, exhibited conductance and responsiveness to KCNQ activators. However, channels assembled from WT-p.Val87_Asn89del concatemers showed impaired conductance, suggesting that p.Val87_Asn89del caused complete loss-of-function with a strong dominant-negative effect on functional WT channels. Therefore, the main pathological mechanism may be related to loss of K+ channel activity, not defects in trafficking.

Asymmetric sensorineural hearing loss is a risk factor for late-onset hearing loss in pediatric cancer survivors following cisplatin treatment.

Ototoxicity is a significant complication of cisplatin treatment. Hearing loss can be symmetric or asymmetric, and may decline after therapy. This study examined the risks of asymmetric and late-onset hearing loss (LOHL) in cisplatin-treated pediatric patients with cancer. A retrospective review of 993 patients' medical and audiological charts from August 1990 to March 2015 was conducted using stringent criteria to characterize patients with asymmetric hearing loss (AHL) or LOHL. Audiologic data were reviewed for 248 patients that received cisplatin to assess cisplatin-induced sensorineural hearing loss and its associated risk factors. Of the patients evaluable for AHL, 26% exhibited this finding. Of those evaluable for LOHL, 42% of the patients' hearing worsened more than 6 months after therapy completion. Radiation and type of cancer diagnosis were major risk factors for both AHL and LOHL. Furthermore, LOHL was linked to age of diagnosis, noncranial radiation, and longer audiologic follow-up. AHL was strongly associated with LOHL-60% of patients with AHL also had LOHL. Logistic regression analysis revealed that patients with AHL (OR 6.3, 95% CI: 2.2-17.8, P=0.0005) or those receiving radiation (OR 3.2, 95% CI: 1.2-8.6, P=0.02) were at greatest risk for LOHL. Children receiving cisplatin therapy are at risk for developing AHL and LOHL. Those that have received radiation and/or with AHL are at increased risk for further hearing decline. Long-term monitoring of these patients is important for early intervention as hearing diminishes.

Next-generation sequencing identified SPATC1L as a possible candidate gene for both early-onset and age-related hearing loss

Hereditary hearing loss (HHL) and age-related hearing loss (ARHL) are two major sensory diseases affecting millions of people worldwide. Despite many efforts, additional HHL-genes and ARHL genetic risk factors still need to be identified. To fill this gap a large genomic screening based on next-generation sequencing technologies was performed. Whole exome sequencing in a 3-generation Italian HHL family and targeted re-sequencing in 464 ARHL patients were performed. We detected three variants in SPATC1L: a nonsense allele in an HHL family and a frameshift insertion and a missense variation in two unrelated ARHL patients. In silico molecular modelling of all variants suggested a significant impact on the structural stability of the protein itself, likely leading to deleterious effects and resulting in truncated isoforms. After demonstrating Spatc1l expression in mice inner ear, in vitro functional experiments were performed confirming the results of the molecular modelling studies. Finally, a candidate-gene population-based statistical study in cohorts from Caucasus and Central Asia revealed a statistically significant association of SPATC1L with normal hearing function at low and medium hearing frequencies. Overall, the amount of different genetic data presented here (variants with early-onset and late-onset hearing loss in addition to genetic association with normal hearing function), together with relevant functional evidence, likely suggest a role of SPATC1L in hearing function and loss.

Characterization of Detailed Audiological Features of Cytomegalovirus Infection: A Composite Cohort Study from Groups with Distinct Demographics.

Congenital cytomegalovirus (cCMV) infection is a common congenital infection that causes sensorineural hearing loss (SNHL). Despite its substantial impact on public health and cost burden, epidemiology and clinical features of CMV-related SNHL have never been reported in the Korean populations. This study investigated the detailed audiologic phenotypes of cCMV infection to see if a specific SNHL pattern is associated with a particular clinical setting. A total of 38 patients with cCMV infection were studied retrospectively. Patients were classified into three groups with distinct demographics: clinically driven diagnosis (n=17), routine newborn CMV screening according to the NICU protocols (n=10), or referral to ENT for cochlear implant (CI) (n=11). The incidence of cCMV infection was 3.6%, showing 33.3% of SNHL among cCMV patients, 38% of asymmetric hearing loss, 29% of late-onset hearing loss, and diverse severity spectrum in patients with CMV-related SNHL. CI recipients with CMV-related SNHL showed a significantly improved speech perception. Surprisingly, in 36.4 % of CI implantees, initial audiological manifestation was significant asymmetry of hearing thresholds between both ears, with better ear retaining significant residual hearing up to 50dB. CMV turns out to be a significant etiology of SNHL, first to date reported in the Korean pediatric population. Analysis of audiologic phenotypes showed a very wide spectrum of SNHL and favorable CI outcomes in case of profound deafness. Especially for the patients with asymmetric hearing loss, close surveillance of hearing should be warranted and CI could be considered on the worse side first, based on the observation of rapid progression to profound deafness of better side.

Characterization of a novel MYO3A missense mutation associated with a dominant form of late onset hearing loss

Whole-exome sequencing of samples from affected members of two unrelated families with late-onset non-syndromic hearing loss revealed a novel mutation (c.2090 T > G; NM_017433) in MYO3A. The mutation was confirmed in 36 affected individuals, showing autosomal dominant inheritance. The mutation alters a single residue (L697W or p.Leu697Trp) in the motor domain of the stereocilia protein MYO3A, leading to a reduction in ATPase activity, motility, and an increase in actin affinity. MYO3A-L697W showed reduced filopodial actin protrusion initiation in COS7 cells, and a predominant tipward accumulation at filopodia and stereocilia when coexpressed with wild-type MYO3A and espin-1, an actin-regulatory MYO3A cargo. The combined higher actin affinity and duty ratio of the mutant myosin cause increased retention time at stereocilia tips, resulting in the displacement of the wild-type MYO3A protein, which may impact cargo transport, stereocilia length, and mechanotransduction. The dominant negative effect of the altered myosin function explains the dominant inheritance of deafness.

Analysis of genotypes and audiological characteristics of children with SLC26A4 gene pathogenic mutations

Objective:To explore the correlation of SLC26A4 genotype and audiology.Method:The subjects were 70 children aged 0 to 7 years old, who were admitted to otological outpatient department.All subjects received nine crystal hereditary deafness gene chip and confirmed by (or)SLC26A4 gene full coding region detection.The patients were diagnosed as homozygous or compound heterozygous mutations.At the same time,acoustic immittance,auditory brainstem response, auditory steady state response and pediatric behavior audiometry, newborn hearing screening and other audiological tests were displayed. According to the genotype, the subjects were divided into two groups: group A (SLC26A4 gene homozygous mutation) in 40 cases, group B (SLC26A4 gene compound heterozygous mutation) in 30 cases. The frequency of SLC26A4 gene mutation, the two groups of genotypes and hearing screening results,the degree of hearing loss and audiometric configurations were analyzed statistically. Result: In 70 patients, the top 4 of the 70 patients with high frequency of mutations were IVS7-2A> G(76.43%), 2168A> G(15.00%), 1226G> A(2.86%) and 2000T> C(2.16%), respectively. 34.29% of newborns passed hearing screening with single or double ears, among which group A and group B were 32.50% and 36.67%,respectively. There was no statistically significant difference between two groups in hearing screening. The degree of hearing loss in group A(56.25%) and group B(48.33%) were mainly profound and there was no significant difference between them. The audiometric configurations: group A(60.00%) was mainly high frequency loss type, while group B(55.00%) was mainly flat type. The difference between them was statistically significant.Conclusion:The mutation sites of SLC26A4 gene were mainly IVS7-2A> G, and the degree of hearing loss was mostly profound. To the audiometric configurations,SLC26A4 gene homozygous mutant were mainly high frequency loss type, while SLC26A4 gene compound heterozygous mutant were mainly flat type. 34.29% children passed universal newborn hearing screening with one ear at least, which indicates SLC26A4 gene mutations can result in late-onset hearing loss, so those patients should be attached great importance..

Further evidence for \u201cgain-of-function\u201d mechanism of DFNA5 related hearing loss

To report two DFNA5 pathogenic splice-site variations and a novel benign frameshift variation to further support the gain-of-function mechanism of DFNA5 related hearing impairment, targeted genes capture and next generation sequencing were performed on selected members from Family 1007208, 1007081 and a sporadic case with sensorineural hearing loss. Reverse transcriptase polymerase chain reaction was conducted on the proband from Family 1007208 to test how the splice-site variation affects the transcription in RNA level. A novel heterozygous splice-site variation c.991-3 C > A in DFNA5 was found in Family 1007208; a known hotspot heterozygous splice-site variation c.991-15_991_13delTTC was identified in Family 1007081. Both the splice-site variations were segregated with the late onset hearing loss phenotype, leading to the skipping of exon 8 at RNA level. In addition, a novel DFNA5 frameshift variation c.116_119delAAAA was found in the sporadic case, but was not segregated with the hearing impairment phenotype. In conclusion, we identified one novel and one known pathogenic DFNA5 splice-site variation in two Chinese Families, as well as a novel DFNA5 frameshift variation c.116_119delAAAA in a sporadic case, which does not the cause for the hearing loss case. Both the two pathogenic splice-site variations and the nonpathogenic frameshift variation provide further support for the specific gain-of-function mechanism of DFNA5 related hearing loss.

Long After Chemotherapy, Cisplatin and Hearing Loss Remain

It is an unfortunate reality that cancer survivors face a lifetime of health consequences related to their cancer treatment. As the population of cancer survivors continues to grow, so does the importance of addressing their medical needs. For patients treated with the chemotherapeutic drug cisplatin, one common consequence of treatment is permanent hearing loss. Reported rates of cisplatin ototoxicity vary widely, though it is believed that at least half of all patients treated with cisplatin will suffer hearing loss. As cisplatin is widely used, this rate of ototoxicity translates to hundreds of thousands of patients affected each year in the United States alone.chemo, cancer, hearing lossAs was detailed in a recent article in this journal, efforts to prevent ototoxicity during cisplatin chemotherapy are ongoing (Hearing Journal. 2018;71(1):26). The success of these efforts likely hinges upon understanding why the cochlea is particularly susceptible to damage by cisplatin. Our recent study, reported in the journal Nature Communications, illustrates the importance of cisplatin pharmacokinetics—the movement of the drug within the body—in understanding ototoxicity (Nat Commun. 2017 Nov 21;8(1):1654). CISPLATIN OTOTOXICITY To effectively study cisplatin ototoxicity in the laboratory, we needed to be able to generate cisplatin-induced hearing loss in mice. Just as a patient receives multiple cycles of cisplatin, each separated by several days of recovery, so did the mice in our study. Auditory brainstem response and distortion product otoacoustic emission testing was performed on the mice, and it showed that cisplatin caused progressive hearing loss that worsened with each successive cycle of administration. Notably, hearing loss also continued to progress weeks after cisplatin administration was ceased, as has been reported for some human patients (J Pediatr Hematol Oncol. 2010 Mar;32(2):119; J Pediatr Hematol Oncol. 2004 Oct;26(10):649; Int J Pediatr Otorhinolaryngol. 2010 Aug;74(8):913). At the core of the cisplatin drug is the metal platinum. In fact, the name cisplatin (“cis-platinum”) is derived from the platinum that gives the drug its cancer-killing properties. This core platinum allowed us to measure tissue concentrations of cisplatin using a highly sensitive technique for detecting metals known as inductively coupled plasma mass spectrometry (ICP-MS). As the mice received successive cycles of cisplatin, drug concentrations across different organs were measured by ICP-MS. Most organs (like the liver, heart, kidney, etc.) effectively eliminated cisplatin in the days and weeks after the drug was given. However, cisplatin remained in the cochlea for much longer, showing no significant decrease in concentration even two months later. We went on to analyze postmortem inner ear tissue from human patients who had received cisplatin, and we found that the drug was retained in their cochleae even 18 months after treatment. In both the laboratory mice and these deceased patients, concentrations of retained cisplatin were highest in the stria vascularis region of the cochlea. This region is responsible for providing blood supply to the cochlea and for maintaining the composition of cochlear fluid. PREVENTIVE OPTIONS Our results demonstrated that over time the cochlea has a higher cumulative exposure to cisplatin than other organs and that, unlike other tissues, the cochlea has very little capacity for removing cisplatin. This may explain why the cochlea is particularly susceptible to cisplatin toxicity. For researchers working to develop a method of preventing cisplatin ototoxicity, our results suggest that the best method of preventing cisplatin ototoxicity may be via prevention of cisplatin uptake into the cochlea in the first place. Once inside the cochlea, cisplatin seems to be there to stay. Identification of drugs that block the uptake of cisplatin through the stria vascularis or directly bind and/or inactivate cisplatin as it enters the cochlea may be a viable path toward prevention of cisplatin ototoxicity. For audiologists, the results of our study underscore the importance of long-term hearing monitoring in patients who have received cisplatin therapy. Late-onset hearing loss is known to occur long after cessation of cisplatin treatment, and these study results suggest that this delayed hearing loss may be related to long-retained cisplatin in the cochlea. Until researchers make significant progress in preventing cisplatin ototoxicity in cancer therapy, it is crucial to continue identifying and treating cancer survivors with cisplatin-induced hearing loss.Andrew M. Breglio, DPhilLisa L. Cunningham, PhD

Identification of a MYO7A mutation in a large Chinese DFNA11 family and genotype–phenotype review for DFNA11

Background: The molecular and genetic research showed the association between DFNA11 and mutations in MYO7A. This research aimed to identify a MYO7A mutation in a family with nonsyndromic autosomal dominant hearing loss.Methods: We have ascertained one large multigenerational Chinese family (Z029) with autosomal dominant late-onset progressive non-syndromic sensorineural hearing loss. Genome-wide linkage analysis of the family mapped the disease locus to the DFNA11 interval, where the MYO7A was considered as a candidate gene. Sequencing of the PCR products was carried out for each sample. One hundred and fifty one control subjects with normal hearing functions were also evaluated.Results: The pathogenic mutation (c.2011G>A) was identified in the family. This mutation co-segregated with hearing loss in this family. No mutation of MYO7A gene was found in the 151 controls.Conclusions: The missense mutation of MYO7A is identified in the family displaying the pedigree consistent with DFNA11. We not only examined the clinical and genetic characteristics of the family, but also provided a basis for genetic counseling. We also summarized and analyzed the phenotypes and genotypes of all DFNA11 families, four of nine are Chinese families, suggesting that MYO7A mutations are not rare. Therefore, we should pay more attention to Chinese patients.

Expression pattern of EYA4 in the common marmoset (Callithrix jacchus) cochlea.

The eyes absent (EYA)-like genes are essential for the formation of sensory organs among fly (Drosophila melanogaster) and mammals. EYA4, one of the vertebrate genes of Eya family, is reported to be causative for late-onset mid-frequency sensorineural hearing loss in humans, while Eya4-deficient mice exhibited congenital profound deafness and otitis media with effusion due to the eustachian tube dysmorphology. Because of the species difference in the phenotype, the pathophysiology of EYA4 in the human cochlea has yet to be elucidated. Here, we examine the expression pattern of EYA4 in the cochlea of common marmoset (Callithrix jacchus), a non-human primate. The results indicated a distinct expression pattern of EYA4 in the adult marmoset cochleae, especially strong in all supporting cells, while in mouse their expressions were diminished. Interestingly, EYA4 expression in the hair cells, supporting cells and neurons was co-localized with sine oculis homeobox-SIX1, a transcription factor essential for the transcriptional activity of EYA4. The results revealed inter-species differences in the expression pattern of EYA4 gene in supporting cells between primates and rodents. The results also indicated a fundamental role of EYA4 in the primate auditory cells. Experiments with primate models such as marmosets or with human cochlear cells may provide cues about the unknown pathogenesis of EYA4-related hearing loss.