Common Deafness Genes Research Articles

Targeted gene sequencing and hearing follow-up in 7501 newborns reveals an improved strategy for newborn hearing screening.

Hearing loss is a common congenital condition. Concurrent newborn hearing and limited genetic screening has been implemented in China for the last decade. However, the role of gene sequencing screening has not been evaluated. In this study, we enrolled 7501 newborns (52.7% male, 47.3% female) in our Newborn Screening with Targeted Sequencing (NESTS) program, and 90 common deafness genes were sequenced for them. Hearing status assessments were conducted via telephone from February 2021 to August 2022, for children aged 3 to 48 months. Of the universal newborn hearing screening, 126 (1.7%) newborns did not pass. Targeted sequencing identified 150 genetically positive newborns (2.0%), with 25 exhibiting dual-positive results in both screening. Following diagnostic audiometry revealed 18 hearing loss newborns and half of them had abnormal results in both screening. The positive predictive value for universal newborn hearing screening alone was merely 14.3% (18/126). However, when combined with targeted sequencing, this rate increased to 36.0% (9/25). Furthermore, limited genetic screening identified 316 carriers of hot-spot variants, but none exhibited biallelic variants. All 15 hot-spot carriers who failed physical screening demonstrated normal hearing during follow-up. In this cohort study of 7501 Newborns, Combining targeted sequencing with universal newborn hearing screening demonstrated technical feasibility and clinical utility of identifying individuals with hearing loss, especially when coupled with genetic counseling and closed-loop management. It is suggested to use this integrated method as an improved strategy instead of the current limited genetic screening program in some regions of China.

Auditory characteristics and disease progression trends of patients with common recessive deafness genes GJB2 and SLC26A4

Patients who aged≥6 years and had hearing loss due to GJB2 or SLC26A4 mutation from the Chinese Deafness Genome Project between January 2020 and December 2023 were included. A total of 43 patients with GJB2 mutation were detected, including 25 males and 18 females, with a mean age of (20.4±11.4) years. There were 20 patients with SLC26A4 mutation, including 9 males and 11 females, with a mean age of (15.7±9.1) years. The mean hearing threshold of GJB2 and SLC26A4 mutation patients was 54.1 (95%CI: 49.1-59.1) decibel hearing level (dB HL) and 66.1 (95%CI: 58.6-73.6) dB HL, respectively. The hearing threshold of GJB2 and SLC26A4 mutation patients increased at a rate of 0.21 (95%CI:-0.15-0.57) dB HL/year and 2.22 (95%CI: 1.46-2.99) dB HL/year, respectively. The current study indicates that patients with SLC26A4 mutation show a progressive trend of hearing decline with the increase of age.

Validating the splicing effect of rare variants in the SLC26A4 gene using minigene assay

BackgroundThe SLC26A4 gene is the second most common cause of hereditary hearing loss in human. The aim of this study was to utilize the minigene assay in order to identify pathogenic variants of SLC26A4 associated with enlarged vestibular aqueduct (EVA) and hearing loss (HL) in two patients.MethodsThe patients were subjected to multiplex PCR amplification and next-generation sequencing of common deafness genes (including GJB2, SLC26A4, and MT-RNR1), then bioinformatics analysis was performed on the sequencing data to identify candidate pathogenic variants. Minigene experiments were conducted to determine the potential impact of the variants on splicing.ResultsGenetic testing revealed that the first patient carried compound heterozygous variants c.[1149 + 1G > A]; [919–2 A > G] in the SLC26A4 gene, while the second patient carried compound heterozygous variants c.[2089 + 3 A > T]; [919–2 A > G] in the same gene. Minigene experiments demonstrated that both c.1149 + 1G > A and c.2089 + 3 A > T affected mRNA splicing. According to the ACMG guidelines and the recommendations of the ClinGen Hearing Loss Expert Panel for ACMG variant interpretation, these variants were classified as “likely pathogenic”.ConclusionsThis study identified the molecular etiology of hearing loss in two patients with EVA and elucidated the impact of rare variants on splicing, thus contributing to the mutational spectrum of pathogenic variants in the SLC26A4 gene.

MPZL2—a common autosomal recessive deafness gene related to moderate sensorineural hearing loss in the Chinese population

BackgroundMutations in MPZL2, the characteristic genetic etiology of autosomal recessive deafness loci 111 (DFNB111), cause non-syndromic and moderate sensorineural hearing loss.MethodsIn this study, we analyzed the phenotype and genotype of eight pedigrees consisting of 10 hearing loss patients with bi-allelic pathogenic or likely pathogenic variants in MPZL2. These patients were identified from a 3272 Chinese patient cohort who underwent genetic testing.ResultsApart from symmetrical and moderate sensorineural hearing loss, the MPZL2-related phenotype was characterized by progressive hearing loss with variation in the onset age (congenital defect to onset at the young adult stage). We determined that in the Chinese population, the genetic load of MPZL2 defects was 0.24% (8/3272) in patients diagnosed with hearing loss and 7.02% (8/114) in patients diagnosed with hereditary moderate sensorineural hearing loss caused by STRC, OTOA, OTOG, OTOGL, TECTA, MPZL2 and others. Three known MPZL2 variants (c.220C > T (p.Gln74*), c.68delC (p.Pro23Leufs*2), c.463delG (p.Ala155Leufs*10)) and a novel start loss variant (c.3G > T (p.Met1?)) were identified. MPZL2 c.220C > T was identified as the hotspot variant in the Chinese population and even in East Asia compared with c.72delA (p.Ile24Metfs*22) in European and West Asia through allele frequency.ConclusionsWe concluded that apart from moderate HL, progressive HL is another character of MPZL2-related HL. No specified variant was verified for the progression of HL, the penetrance and expressivity cannot be determined yet. A novel MPZL2 variant at the start codon was identified, enriching the variant spectrum of MPZL2. The hotspot variants of MPZL2 vary in different ethnicities. This study provides valuable data for the diagnosis, prognosis evaluation and genetic counseling of patients with moderate sensorineural hearing loss related to MPZL2.

Hereditary deafness carrier screening in 9,993 Chinese individuals.

Background: Preconception or prenatal carrier screening plays an important role in reproductive decision-making, but current research on hereditary deafness is limited. This study aimed to investigate the carrier frequencies of common deafness genes in the Chinese population who underwent carrier screening and to follow up on pregnancy outcomes in high-chance couples. Methods: Individual females or couples in preconception or early pregnancy were recruited from two hospitals in China. Carrier screening for common deafness genes in the Chinese population, including the GJB2 and SLC26A4 genes, was performed using next-generation sequencing technology. Genetic counseling was provided to subjects before and after testing. Results: Of the 9,993 subjects screened, the carrier rate was 2.86% for the GJB2 gene and 2.63% for the SLC26A4 gene. The variant with the highest carrier frequency in GJB2 was c.235delC (1.89%), and c.919-2A>G (1.08%) in SLC26A4. Of the six high-chance couples, four made alternative reproductive decisions (three with prenatal diagnosis and one with preimplantation genetic testing), with consequent termination of the birth of two affected fetuses. Conclusion: These findings confirmed the clinical utility of preconception or prenatal carrier screening for hereditary deafness.

Genetic correction of induced pluripotent stem cells from a DFNA36 patient results in morphologic and functional recovery of derived hair cell-like cells

BackgroundTMC1 is one of the most common deafness genes causing DFNA36. Patient-derived human induced pluripotent stem cells (iPSCs) provide an opportunity to modelling diseases. TMC1 p.M418K mutation in human is orthologous to Beethoven mice. Here, we investigated the differentiation, morphology and electrophysiological properties of hair cell-like cells (HC-like cells) derived from DFNA36 patient.MethodsInner ear HC-like cells were induced from iPSCs derived from DFNA36 (TMC1 p.M418K) patient (M+/−), normal control (M+/+) and genetic corrected iPSCs (M+/C). Immunofluorescence, scanning electron microscopy and whole-cell patch-clamp were used to study the mechanism and influence of TMC1 p.M418K mutation.ResultsIn this study we successfully generated HC-like cells from iPSCs with three different genotypes. HC-like cells from M+/− showed defected morphology of microvilli and physiological properties compared to M+/+. HC-like cells from M+/C showed recovery in morphology of microvilli and physiological properties.ConclusionsOur results indicate that TMC1 p.M418K mutation didn’t influence inner ear hair cell differentiation but the morphology of microvilli and electrophysiological properties and gene correction induced recovery. CRISPR/Cas9 gene therapy is feasible in human patient with TMC1 p.M418K mutation.

Genome Sequencing Unveils the Role of Copy Number Variants in Hearing Loss and Identifies Novel Deletions With Founder Effect in the DFNB1 Locus

Sensorineural hearing loss is a prevalent disorder with significant genetic involvement, which is often challenging to diagnose due to genetic heterogeneity. Exome sequencing (ES) has been a standard diagnostic tool for sensorineural hearing loss, but its limitations in detecting copy number variants (CNVs) and intronic variants have prompted the exploration of genome sequencing (GS) for improved diagnostic yield. We conducted GS on 46 hearing loss families with previously negative ES results and an additional cohort of 36 patients with a monoallelic pathogenic variant in GJB2 (the most common deafness gene). Additionally, the impact of a previously unrecognized novel 125‐kb deletion in the DFNB1 locus on GJB2 expression was assessed using quantitative polymerase chain reaction (qPCR), and haplotype analysis was performed to characterize the deletion. GS diagnosed eight cases (17%, 8/46) in the ES‐negative cohort, primarily attributed to CNVs (6/8). Notably, a previously unrecognized 125 kb deletion in the DFNB1 region was identified, affecting GJB2 expression and characterizing it as a founder effect in East Asian. In 47 patients with a monoallelic GJB2 variant, 15% (95% CI, 7.4%–28%) were diagnosed with DFNB1 deletions. Analysis of the gnomAD database revealed the prevalence and ethnic diversity of DFNB1 deletions, with the novel 125 kb deletion emerging as a prominent pathogenic variant in East Asian, non‐Finnish European, and admixed American populations. Our study highlights the utility of GS in diagnosing sensorineural hearing loss. The identification of DFNB1 deletions underscores their significant contribution to hearing loss etiology, advocating for their inclusion in routine diagnostic testing. We propose GS as a primary genetic testing approach for patients with hearing loss, offering comprehensive genomic analysis and the potential for improved diagnostic accuracy.

Evaluation of hearing and speech rehabilitation after cochlear implantation in children with Waardenburg syndrome

Objective:By comparing the hearing and speech rehabilitation effects of cochlear implantation （CI） in children with Waardenburg syndrome （WS） and children with common deafness genes （SLC26A4, GJB2） in the Chinese population, and the hearing and speech rehabilitation effects of bilateral CI and unilateral CI in children with WS, to provide a reference for clinical CIin children with WS. Methods:Follow up and return visit 72 pedestrian cochlear implant children with severe and above sensorineural hearing loss and clear gene mutation type diagnosed by Kunming Children's Hospital from 2017 to 2019, including 24 cases in the WS group, 24 cases in the control group （SLC26A4 deafness group and GJB2 deafness group）. All enrolled children were evaluated for auditory and speech ability 12 months after startup. Results:The hearing aid threshold, the correct recognition rate of speech recognition ability evaluation, IT-MAIS / MAIS score rate, CAP score, SIR score, there was no significant difference（P>0.05）. The correct recognition rates of IT-MAIS / MAIS score, SIR score, natural environment sound recognition, vowel recognition, tone recognition, monosyllabic word recognition, disyllabic word recognition and short sentence recognition in children with WS bilateral CI were significantly higher than those in children with WS unilateral CI （P<0.05）. There was no significant difference in CAP score, initial recognition and correct recognition rate of trisyllabic words between children with WS bilateral CI and children with WS unilateral CI （P>0.05）. Conclusion:Common deafness genes in children with WS and Chinese population （SLC26A4, GJB2） the effect of cochlear implantation on hearing and speech rehabilitation of sick children is equivalent. For children with severe and above sensorineural hearing loss associated with this syndrome, CI can be used clinically to improve their hearing and speech ability. WS bilateral CI has advantages in some hearing and speech abilities compared with unilateral CI, so those whomeet the conditions should be encouraged bilateral implantation.

Genetic screening of common genetic deafness in 60,391 women of childbearing age and intervention of birth defects.

At least 60% of cases of severe hearing loss result from genetic factors. In this study genetic screening was carried out for common genetic deafness in women of childbearing age to prevent deafness and birth defects via providing genetic counseling and follow-up services for high-risk families. In total 60,391 pre-pregnancy/early-gestation women who received treatment in second-level or above hospitals in Weihai from February 2017 to December 2019 were selected. Venous or peripheral blood was collected to make dried blood slices on filter paper to extract genomic DNA, and high-throughput sequencing was applied to detect 20 variant sites in 4 common deafness genes (GJB2, GJB3, SLC26A4 and mitochondrial 12S rRNA) in the Chinese population. The spouses of women with deafness gene variants were sequenced. In total 3,761 carriers with deafness gene variants were detected in 60,391 women of childbearing age, with a carrier rate of 6.2%. Among them, 1,739 women (2.88%) only carried GJB2 pathogenic variants. The carrying rate of c.235delC in GJB2 pathogenic variants was the highest at 2.08%. 1,553 women (2.58%) only carried SLC26A4 pathogenic variants. The carrying rate of c.919-2A>G in SLC26A4 pathogenic variants was the highest at 1.63%. 300 women (0.5%) only carried GJB3 variants, and 125 women (0.2%) carried the mitochondrial drug-sensitive gene variant. This screening model will greatly reduce the birth rate of children with hearing disabilities and is an effective way to prevent newborn deafness. In addition, genetic screening provided the related knowledge of hereditary deafness, especially strengthening genetic counseling and the clinical decision making from the genetic screening.

Genetic profiles of non-syndromic severe-profound hearing loss in Chinese Hans by whole-exome sequencing

Hereditary hearing loss is highly heterogeneous. Despite over 120 non-syndromic deafness genes have been identified, there are still some of novel genes and variants being explored. In the study, we investigated 105 Chinese Han children with non-syndromic, prelingual, severe-profound hearing loss by whole-exome sequencing on DNA samples. The most common deafness gene was GJB2, mainly in variant c.235delC (p.Leu79CysfsTer3). 14 children were identified with pathogenic mutations in three genes, GJB2, SLC26A4, and OTOF. Two mutations have been identified to be pathogenic and not recorded previously, including c.4691G > A (p.Trp1564Ter) and c.3928_3930dup (p.Lys1310dup) in OTOF. The rare variants c.1349G > A (p.Arg450His) and c.456 T > G (p.Asn152Lys) in GSDME, and c.1595G > T (p.Ser532Ile) in SLC26A4 were detected. The frequency of nonsense variant c.2359G > T (p.Glu787Ter) in OTOA was very high in 17 cases. Four of them were identified to be digenic inheritance, including GJB2 and COL4A4, GJB2 and EYA1, GJB2 and COL4A5, and GJB2 and DFNA5. The findings showed that a novel pathogenic variant and rare variants may be associated with severe and profound hearing loss.

Analysis of GJB2 Gene Mutations in 1330 Deafness Cases of Major Ethnic Groups in Northwest China.

Background: The GJB2 gene is the most common deafness gene, and epidemic characteristics have obvious racial specificity. Our study aimed to investigate the prevalence and ethnic specificity of the GJB2 gene in deafness in major ethnic groups in Northwest China, evaluate the value of molecular screening for deafness in minority populations, and explore the strategies and methods for genetic diagnosis. Methods: Ethics approval was obtained to collect 1330 cases of moderate to very severe nonsyndromic sensorineural deafness in northwestern China. The mutation characteristics of ethnic minorities were analyzed and compared with those of 464 patients with nonsyndromic sensorineural deafness among ethnic Han in the northwestern from research group by Sequence Scanner V25.0. Then, we analyzed the ethnic specificity of the mutations. Results: A total of 15 GJB2 sequence changes were detected in 1330 minority patients. The study showed that the allele frequency in Tibetan patients was significantly lower than that in Hui and Dongxiang patients, that in Uygur patients was significantly lower than that in Han and Hui patients, and that in Kazak and Tibetan patients was significantly lower than that in Han patients, and the differences between other ethnic groups were not statistically significant. Each ethnic group has a unique GJB2 gene mutation spectrum, and its hotspot mutation distribution has its own characteristics, with c.235delC, c.109 G > A, c.299-300delAT, and c.35delG being common. Conclusions: It has been confirmed that GJB2 gene mutation has a high prevalence in patients with nonsyndromic sensorineural hearing loss in Northwest China. Each ethnic group has a unique mutation spectrum for the GJB2 gene, which is related to its genetic background. It is necessary to develop a corresponding gene diagnosis strategy according to the hotspot mutations and mutation spectrum of each ethnic group.

The screening report of hearing and the common deafness gene in the elderly.

The screening report of hearing and the common deafness gene in the elderly.

Targeted next-generation sequencing of deaf patients from Southwestern China.

BackgroundTargeted next‐generation sequencing is an efficient tool to identify pathogenic mutations of hereditary deafness. The molecular pathology of deaf patients in southwestern China is not fully understood.MethodsIn this study, targeted next‐generation sequencing of 127 deafness genes was performed on 84 deaf patients. They were not caused by common mutations of GJB2 gene, including c.35delG, c.109 G>A, c.167delT, c.176_191del16, c.235delC and c.299_300delAT.ResultsIn the cohorts of 84 deaf patients, we did not find any candidate pathogenic variants in 14 deaf patients (16.7%, 14/84). In other 70 deaf patients (83.3%, 70/84), candidate pathogenic variants were identified in 34 genes. Of these 70 deaf patients, the percentage of “Solved” and “Unsolved” patients was 51.43% (36/70) and 48.57% (34/70), respectively. The most common causative genes were SLC26A4 (12.9%, 9/70), MT‐RNR1 (11.4%, 8/70), and MYO7A (2.9%, 2/70) in deaf patients. In “Unsolved” patients, possible pathogenic variants were most found in SLC26A4 (8.9%, 3/34), MYO7A (5.9%, 2/34), OTOF (5.9%, 2/34), and PDZD7 (5.9%, 2/34) genes. Interesting, several novel recessive pathogenic variants were identified, like SLC26A4 c.290T>G, SLC26A4 c.599A>G, PDZD7c.490 C>T, etc.ConclusionIn addition to common deafness genes, like GJB2, SLC26A4, and MT‐RNR1 genes, other deafness genes (MYO7A, OTOF, PDZD7, etc.) were identified in deaf patients from southwestern China. Therefore, the spectrum of deafness genes in this area should be further studied.

Local Macrophage-Related Immune Response Is Involved in Cochlear Epithelial Damage in Distinct Gjb2-Related Hereditary Deafness Models.

The macrophage-related immune response is an important component of the cochlear response to different exogenous stresses, including noise, ototoxic antibiotics, toxins, or viral infection. However, the role of the immune response in hereditary deafness caused by genetic mutations is rarely explored. GJB2, encoding connexin 26 (Cx26), is the most common deafness gene of hereditary deafness. In this study, two distinct Cx26-null mouse models were established to investigate the types and underlying mechanisms of immune responses. In a systemic Cx26-null model, macrophage recruitment was observed, associated with extensive cell degeneration of the cochlear epithelium. In a targeted-cell Cx26-null model, knockout of Cx26 was restricted to specific supporting cells (SCs), which led to preferential loss of local outer hair cells (OHCs). This local OHC loss can also induce a macrophage-related immune response. Common inflammatory factors, including TNF-α, IL-1β, Icam-1, Mif, Cx3cr1, Tlr4, Ccl2, and Ccr2, did not change significantly, while mRNA of Cx3cl1 was upregulated. Quantitative immunofluorescence showed that the protein expression of CX3CL1 in Deiters cells, a type of SC coupled with OHCs, increased significantly after OHC death. OHC loss caused the secondary death of spiral ganglion neurons (SGNs), while the remaining SGNs expressed high levels of CX3CL1 with infiltrated macrophages. Taken together, our results indicate that CX3CL1 signaling regulates macrophage recruitment and that enhancement of macrophage antigen-presenting function is associated with cell degeneration in Cx26-null mice.

Next-generation sequencing identifies rare pathogenic and novel candidate variants in a cohort of Chinese patients with syndromic or nonsyndromic hearing loss.

BackgroundHearing loss (HL) is a common sensory disorder in humans characterized by extreme clinical and genetic heterogeneity. In recent years, next‐generation sequencing (NGS) technologies have proven to be highly effective and powerful tools for population genetic studies of HL. Here, we analyzed clinical and molecular data from 21 Chinese deaf families who did not have hotspot mutations in the common deafness genes GJB2, SLC26A4, GJB3, and MT‐RNR1.MethodTargeted next‐generation sequencing (TGS) of 127 known deafness genes was performed in probands of 12 families, while whole‐exome sequencing (WES) or trio‐WES was used for the remaining nine families.ResultsPotential pathogenic mutations in a total of 12 deafness genes were identified in 13 probands; the mutations were observed in GJB2, CDH23, EDNRB, MYO15A, OTOA, OTOF, TBC1D24, SALL1, TMC1, TWNK, USH1C, and USH1G, with eight of the identified mutations being novel. Further, a copy number variant (CNV) was detected in one proband with heterozygous deletion of chromosome 4p16.3‐4p15.32. Thus, the total diagnostic rate using NGS in our deafness patients reached 66.67% (14/21).ConclusionsThese results expand the mutation spectrum of deafness‐causing genes and provide support for the use of NGS detection technologies for routine molecular diagnosis in Chinese deaf populations.

Analysis of deafness gene variant screening of 7875 neonatal cases in Dongying area of Shandong

To determine the types and frequency of deafness-related variants among 7875 newborns from Dongying area of Shandong Province. One hundred loci of 18 common deafness genes were subjected to semiconductor sequencing. Variant site, frequency and distribution of the variants were analyzed. In total 552 deafness gene variants were detected among the 7875 newborns, which yielded a detection rate of 7.01%. Among these, common variant sites for GJB2, SLC26A4 and GJB3 genes were c.235delC, IVS7-2A>G and c.538C>T, respectively. The variant frequencies of matrilinear inheritance deafness genes MT-CO1, MT-RNR1, MT-TL1 and MT-TS1 were 0.38%, 0.25%, 0.1% and 0.01%, respectively. Four newborns were diagnosed with deafness, among which one had unilateral hearing loss. Analysis of the proportions of neonatal deafness-related variants in five counties of Dongying showed that the highest variant rate for the SLC26A4 gene compared with GJB2 was in Lijin county (51.76% vs. 40%), while the lowest was in Hekou county (30.77% vs. 56.41%). The carrier rate of deafness-related variants in Dongying area is higher than other regions of China, which may be attributed to the increased types and variant sites covered by the semiconductor sequencing method compared with the chip method and time-of-flight mass spectrometry. Due to geographical and population aggregation factors, the proportion of deafness variants in the five counties of Dongying differed significantly. Above results may provide a guide for the prevention of congenital deafness in Dongying area.

Clinical and genetic study of 12 Chinese Han families with nonsyndromic deafness.

BackgroundNonsyndromic hearing loss is clinically and genetically heterogeneous. In this study, we characterized the clinical features of 12 Chinese Han deaf families in which mutations in common deafness genes GJB2, SLC26A4, and MT‐RNR1 were excluded.MethodsTargeted next‐generation sequencing of 147 known deafness genes was performed in probands of 10 families, while whole‐exome sequencing was applied in those of the rest two.ResultsPathogenic mutations in a total of 11 rare deafness genes, OTOF, CDH23, PCDH15, PDZD7, ADGRV1, KARS, OTOG, GRXCR2, MYO6, GRHL2, and POU3F4, were identified in all 12 probands, with 16 mutations being novel. Intrafamilial cosegregation of the mutations and the deafness phenotype were confirmed by Sanger sequencing.ConclusionOur results expanded the mutation spectrum and genotype‒phenotype correlation of nonsyndromic hearing loss in Chinese Hans and also emphasized the importance of combining both next‐generation sequencing and detailed auditory evaluation to achieve a more accurate diagnosis for nonsyndromic hearing loss.

Application of PCR reverse dot blot in non-syndromic deafness gene detection

Objective:To detect 20 common deafness gene mutations in non- syndromic deafness patients in China using PCR- RDB, and analyze and summarize the mutation data to explore the clinical value of this method. Method:The PCR- RDB and Sanger sequencing were used to detect 20 common mutations of four deafness genes（GJB2, GJB3, SLC26A4 and mtDNA） in 500 patients with non- syndromic hearing loss . The Sanger sequencing was used to compare the sensitivity, specificity, positive predictive value, negative predictive value, and total coincidence rate of the deafness mutation detected by PCR- RDB. Result:A total of 500 samples were detected. 147 wild- type samples, 81 homozygous mutant samples, 240 heterozygous mutant samples, 32 composite heterozygous mutant samples were detected using the PCR- RDB within the range of 20 gene mutations, which were identical to the Sanger sequencing results. GJB2 c.235delC and SLC26A4 c.919- 2 A>G are the most common hotspot mutations in this study, followed by mtDNA m. 1555 A>G. Compared with the Sanger sequencing method, the sensitivity, specificity, positive predictive value, negative predictive value, and total coincidence rate of the real- time fluorescence PCR melting curve method were 100%, and the Kappa value was one. Conclusion:PCR reverse dot-blot hybridization is a simple, rapid, sensitive and specific method for detecting 20 mutations of 4 common deafness genes in Chinese population, it is expected to be used in clinical detection of deafness genes in the future.

Congenital Middle Ear Malformation with Common Deafness Gene Mutation Analysis: A Review of 813 Profound Sensorineural Hearing Loss Child Patients.

Deafness gene variants play a key role in inner ear malformations. However, the relationship between congenital middle ear malformations and common deafness genes (GJB2, SLC26A4, and mtDNA) in profound sensorineural hearing loss (SNHL) child patients remains poorly investigated. Here we showed that there was no statistical significance in the total mutation frequency of the three common deafness genes in the middle ear malformation group (21.2%, 41/193) in comparison with the normal middle ear and inner ear group (21.0%, 116/553) (χ2 = 0.0061, p = 0.940). Moreover, the mutation ratio of GJB2 and SLC26A4 in the middle ear malformation group (18.7%, 36/193; 2.6%, 5/193) was not significantly different from that in the normal middle ear and inner ear group (17.7%, 98/553; 2.4%, 13/553) (χ2 = 0.084, p = 0.772; χ2 = 0.0000, p = 1.000). The mutation ratio of GJB2 235delC and GJB2 79G>A in the middle ear malformation group (8.8%, 17/193; 8.8%, 17/193) was almost the same to that in the normal middle ear and inner ear group (8.6%, 48/553; 6.7%, 37/553) (χ2 = 0.0030, p = 0.957; χ2 = 0.9556, p = 0.328). The high jugular bulb subgroup analysis also showed the same results. Our findings suggested that GJB2, SLC26A4, and mtDNA mutations might not be related to the middle ear malformations in profound SNHL child patients. Anat Rec, 303:594-599, 2020. © 2019 American Association for Anatomy.

Whole-exome sequencing identifies rare pathogenic and candidate variants in sporadic Chinese Han deaf patients.

Genetic causes of hearing loss are highly heterogeneous and often ethnically specific. In recent years, a variety of next-generation sequencing (NGS) panels have been developed to target deafness-causative genes. Whole-exome sequencing (WES), on the other hand, was rarely used for genetic testing for deafness. In this study, we performed WES in 38 sporadic Chinese Han deaf patients who have been pre-excluded for mutations in common deafness genes GJB2, SLC26A4 and MT-RNR1. Non-synonymous variants have been filtered based on their minor allele frequencies in public databases and ethnically matched controls. Bi-allelic pathogenic mutations in eight deafness genes, OTOF, TRIOBP, ESPN, HARS2, CDH23, MYO7A, USH1C and TJP2, were identified in 10 patients, with 17 mutations identified in this study not being associated with deafness previously. For the rest 28 patients, possibly bi-allelic rare non-synonymous variants in an averaged 4.7 genes per patient were identified as candidate pathogenic causes for future analysis. Our study showed that WES may provide a unified platform for genetic testing of deafness and enables retro-analyzing when new causative genes are revealed.