Deafness Genes Research Articles

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

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

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.

Vestibular Deficits in Deafness: Clinical Presentation, Animal Modeling, and Treatment Solutions.

The inner ear is responsible for both hearing and balance. These functions are dependent on the correct functioning of mechanosensitive hair cells, which convert sound- and motion-induced stimuli into electrical signals conveyed to the brain. During evolution of the inner ear, the major changes occurred in the hearing organ, whereas the structure of the vestibular organs remained constant in all vertebrates over the same period. Vestibular deficits are highly prevalent in humans, due to multiple intersecting causes: genetics, environmental factors, ototoxic drugs, infections and aging. Studies of deafness genes associated with balance deficits and their corresponding animal models have shed light on the development and function of these two sensory systems. Bilateral vestibular deficits often impair individual postural control, gaze stabilization, locomotion and spatial orientation. The resulting dizziness, vertigo, and/or falls (frequent in elderly populations) greatly affect patient quality of life. In the absence of treatment, prosthetic devices, such as vestibular implants, providing information about the direction, amplitude and velocity of body movements, are being developed and have given promising results in animal models and humans. Novel methods and techniques have led to major progress in gene therapies targeting the inner ear (gene supplementation and gene editing), 3D inner ear organoids and reprograming protocols for generating hair cell-like cells. These rapid advances in multiscale approaches covering basic research, clinical diagnostics and therapies are fostering interdisciplinary research to develop personalized treatments for vestibular disorders.

Genetic testing for pediatric hearing loss: no time to waste.

Since the discovery of the first human deafness gene a quarter of a century ago, our approach toclinical evaluation of children with hearing loss has changed dramatically. What was once a low-yield scattershot approach has changed to a clearly definable pathway involving genetic testing, imaging, and congenital cytomegalovirus testing. There still however is a great deal of work to be done to expand the correct use of this testing, particularly genetic testing.

Autosomal dominant non-syndromic hearing loss maps to DFNA33 (13q34) and co-segregates with splice and frameshift variants in ATP11A, a phospholipid flippase gene

Sequencing exomes/genomes have been successful for identifying recessive genes; however, discovery of dominant genes including deafness genes (DFNA) remains challenging. We report a new DFNA gene, ATP11A, in a Newfoundland family with a variable form of bilateral sensorineural hearing loss (SNHL). Genome-wide SNP genotyping linked SNHL to DFNA33 (LOD = 4.77), a locus on 13q34 previously mapped in a German family with variable SNHL. Whole-genome sequencing identified 51 unremarkable positional variants on 13q34. Continuous clinical ascertainment identified several key recombination events and reduced the disease interval to 769 kb, excluding all but one variant. ATP11A (NC_000013.11: chr13:113534963G>A) is a novel variant predicted to be a cryptic donor splice site. RNA studies verified in silico predictions, revealing the retention of 153 bp of intron in the 3′ UTR of several ATP11A isoforms. Two unresolved families from Israel were subsequently identified with a similar, variable form of SNHL and a novel duplication (NM_032189.3:c.3322_3327+2dupGTCCAGGT) in exon 28 of ATP11A extended exon 28 by 8 bp, leading to a frameshift and premature stop codon (p.Asn1110Valfs43Ter). ATP11A is a type of P4-ATPase that transports (flip) phospholipids from the outer to inner leaflet of cell membranes to maintain asymmetry. Haploinsufficiency of ATP11A, the phospholipid flippase that specially transports phosphatidylserine (PS) and phosphatidylethanolamine (PE), could leave cells with PS/PE at the extracellular side vulnerable to phagocytic degradation. Given that surface PS can be pharmaceutically targeted, hearing loss due to ATP11A could potentially be treated. It is also likely that ATP11A is the gene underlying DFNA33.

The clinical phenotype and gene analysis of syndromic deafness with PTPN11 gene mutation

Objective: To analyze the clinical phenotype and screen the genetic mutations of hereditary deafness in three deaf families to clarify their molecular biology etiology. Methods: From January 2019 to January 2020, three deaf children and family members were collected for medical history, physical examination, audiology evaluation, electrocardiogram and cardiac color Doppler ultrasound, temporal bone CT examination, and peripheral blood DNA was obtained for high-throughput sequencing of deafness genes. Sanger sequencing was performed to verify the variant sites among family members. The pathogenicity of the variants was evaluated according to the American College of Medical Genetics and Genomics. Results: The probands in the three families had deafness phenotypes. In family 1, proband had multiple lentigines, special facial features, growth retardation, pectus carinatum, abnormal skin elasticity, cryptorchidism and other manifestations. In family 2, proband had special facial features, growth retardation and abnormal heart, and the proband in family 3 had growth retardation and abnormal electrocardiogram. Genetic testing of three families detected three heterozygous mutations in the PTPN11 gene: c.1391G>C (p.Gly464Ala), c.1510A>G (p.Met504Val), c.1502G>A (p.Arg501Lys). All three sites were missense mutations, and the mutation sites were highly conserved among multiple homologous species. Based on clinical manifestations and genetic test results, proband 1 was diagnosed with multiple lentigines Noonan syndrome, and probands 2 and 3 were diagnosed with Noonan syndrome. Conclusion: Missense mutations in the PTPN11 gene may be the cause of the disease in the three deaf families. This study enriches the clinical phenotype and mutation spectrum of the PTPN11 gene in the Chinese population.

Whole exome analysis of patients in Japan with hearing loss reveals high heterogeneity among responsible and novel candidate genes

BackgroundHeterogeneous genetic loci contribute to hereditary hearing loss; more than 100 deafness genes have been identified, and the number is increasing. To detect pathogenic variants in multiple deafness genes, in addition to novel candidate genes associated with hearing loss, whole exome sequencing (WES), followed by analysis prioritizing genes categorized in four tiers, were applied.ResultsTrios from families with non-syndromic or syndromic hearing loss (n = 72) were subjected to WES. After segregation analysis and interpretation according to American College of Medical Genetics and Genomics guidelines, candidate pathogenic variants in 11 previously reported deafness genes (STRC, MYO15A, CDH23, PDZD7, PTPN11, SOX10, EYA1, MYO6, OTOF, OTOG, and ZNF335) were identified in 21 families. Discrepancy between pedigree inheritance and genetic inheritance was present in one family. In addition, eight genes (SLC12A2, BAIAP2L2, HKDC1, SVEP1, CACNG1, GTPBP4, PCNX2, and TBC1D8) were screened as single candidate genes in 10 families.ConclusionsOur findings demonstrate that four-tier assessment of WES data is efficient and can detect novel candidate genes associated with hearing loss, in addition to pathogenic variants of known deafness genes.

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.

Report of rare and novel mutations in candidate genes in a cohort of hearing-impaired patients.

BackgroundMany hearing‐impaired patients carry mutations in rare or novel genes undetected in regular genetic hot regions/genes screening.MethodsWe collected clinical and genetic data from subjects with hearing loss who visited our department for genetic counseling. Next‐generation sequencing was conducted after 154 deafness‐related genes were captured using a designed genes panels in 14 unrelated families (37 participants). The results were filtered and assessed with in silico tools, in combination with pedigree mapping.ResultsTen mutations in regular deafness genes (GJB2, SLC26A4) and uncommon genes (OTOF, MYO7A, MYO15A, and KARS) were detected, which constituted 57.2% of yielded rate. In particular, two patients with nonsyndromic deafness carried biallelic KARS mutations. In addition, we identified an unreported digenic mutational inheritance in GRP98/USH2A genes in a proband with isolated hearing loss. Functional analyses and molecular modeling suggested the damaging consequence of these variants on encoded proteins. According to the variant pathogenicity guidelines, the 17 identified variants in total were classified as “pathogenic” or “likely pathogenic.”ConclusionThe candidate mutations in deafness genes were suggested to be co‐segregated in at least 57.2% of the studied pedigrees. This is the new report of rare/novel mutations causing inherited hearing loss in Chinese.

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.

The Roles of Solute Carriers in Auditory Function.

Solute carriers (SLCs) are important transmembrane transporters with members organized into 65 families. They play crucial roles in transporting many important molecules, such as ions and some metabolites, across the membrane, maintaining cellular homeostasis. SLCs also play important roles in hearing. It has been found that mutations in some SLC members are associated with hearing loss. In this review, we summarize SLC family genes related with hearing dysfunction to reveal the vital roles of these transporters in auditory function. This summary could help us understand the auditory physiology and the mechanisms of hearing loss and further guide future studies of deafness gene identification.

Variant analysis of 92 Chinese Han families with hearing loss

BackgroundHearing loss (HL) is the most frequent sensory deficit in humans, HL has strong genetic heterogeneity. The genetic diagnosis of HL is very important to aid treatment decisions and to provide prognostic information and genetic counseling for the patient’s family.MethodsWe undertook pedigree analysis in 92 Chinese non-syndromic HL patients by targeted next-generation sequencing and Sanger sequencing.ResultsAmong the 92 HL patients, 18 were assigned a molecular diagnosis with 33 different variants in 14 deafness genes. Eighteen of the variants in 12 deafness genes were novel. Variants in TMC1, CDH23, LOXHD1 and USH2A were each detected in two probands, and variants in POU3F4, OTOA, GPR98, GJB6, TRIOBP, SLC26A4, MYO15A, TNC, STRC and TMPRSS3 were each detected in one proband.ConclusionOur findings expand the spectrum of deafness gene variation, which will inform genetic diagnosis of deafness and add to the theoretical basis for the prevention of deafness.

Concurrent Hearing and Genetic Screening among Newborns in Ningbo, China.

Objective To detect the carrier rates of deafness gene variants in populations in Ningbo and analyze the risk of hereditary hearing loss through concurrent hearing and genetic screening tests. Methods Two thousand one hundred and seventy-four newborns were enrolled from November 2018 to August 2019. All subjects underwent hearing screening and newborn deafness genetic screening with 15 variants in 4 genes, and the positive sites were simultaneously verified by sequencing. Results The total carrier rate of genetic variants in Ningbo reached 4.32%, when GJB2 c.235delC was the variant with the highest prevalence (2.12%), approximately accounting for 48.9% of the total carrier frequency. The carrier frequency of SLC26A4 c.919-2A>G was 0.87%, while the most common variant in mitochondrial DNA (mtDNA) MT-RNR1 gene was m.1555A>G, and its carrier frequency was 0.184%. In the OAE testing, 92 newborns passing hearing screening were tested positively for variants in 4 genes, and 2 of 42 newborns who failed in the first hearing test were found to mutate in 4 genes. Conclusion Herein, the results concerning the carrier rates for deafness gene mutations of Ningbo population are reported. Our study is beneficial to the insight into the deafness genomic epidemiology for deafness genes in Ningbo population and provides the reference for healthcare in Ningbo.

Predicting pathogenicity for novel hearing loss mutations based on genetic and protein structure approaches

Hearing loss is a heterogeneous disorder. Identification of causative mutations is demanding due to genetic heterogeneity. In this study, we investigated the genetic cause of sensorineural hearing loss in patients with severe/profound deafness. After the exclusion of GJB2-GJB6 mutations, we performed whole exome sequencing in 32 unrelated Argentinean families. Mutations were detected in 16 known deafness genes in 20 patients: ACTG1, ADGRV1 (GPR98), CDH23, COL4A3, COL4A5, DFNA5 (GSDDE), EYA4, LARS2, LOXHD1, MITF, MYO6, MYO7A, TECTA, TMPRSS3, USH2A and WSF1. Notably, 11 variants affecting 9 different non-GJB2 genes resulted novel: c.12829C > T, p.(Arg4277*) in ADGRV1; c.337del, p.(Asp109*) and c.3352del, p.(Gly1118Alafs*7) in CDH23; c.3500G > A, p.(Gly1167Glu) in COL4A3; c.1183C > T, p.(Pro395Ser) and c.1759C > T, p.(Pro587Ser) in COL4A5; c.580 + 2 T > C in EYA4; c.1481dup, p.(Leu495Profs*31) in LARS2; c.1939 T > C, p.(Phe647Leu), in MYO6; c.733C > T, p.(Gln245*) in MYO7A and c.242C > G, p.(Ser81*) in TMPRSS3 genes. To predict the effect of these variants, novel protein modeling and protein stability analysis were employed. These results highlight the value of whole exome sequencing to identify candidate variants, as well as bioinformatic strategies to infer their pathogenicity.

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.

Interferon regulatory factor-7 is required for hair cell development during zebrafish embryogenesis.

Interferon regulatory factor‐7 (IRF7) is an essential regulator of both innate and adaptive immunity. It is also expressed in the otic vesicle of zebrafish embryos. However, any role for irf7 in hair cell development was uncharacterized. Does it work as a potential deaf gene to regulate hair cell development? We used whole‐mount in situ hybridization (WISH) assay and morpholino‐mediated gene knockdown method to investigate the role of irf7 in the development of otic vesicle hair cells during zebrafish embryogenesis. We performed RNA sequencing to gain a detailed insight into the molecules/genes which are altered upon downregulation of irf7. Compared to the wild‐type siblings, knockdown of irf7 resulted in severe developmental retardation in zebrafish embryos as well as loss of neuromasts and damage to hair cells at an early stage (within 3 days post fertilization). Coinjection of zebrafish irf7 mRNA could partially rescued the defects of the morphants. atp1b2b mRNA injection can also partially rescue the phenotype induced by irf7 gene deficiency. Loss of hair cells in irf7‐morphants does not result from cell apoptosis. Gene expression profiles show that, compared to wild‐type, knockdown of irf7 can lead to 2053 and 2678 genes being upregulated and downregulated, respectively. Among them, 18 genes were annotated to hair cell (HC) development or posterior lateral line (PLL) development. All results suggest that irf7 plays an essential role in hair cell development in zebrafish, indicating that irf7 may be a member of deafness gene family.

A Bibliometric Analysis of Deafness Gene Literature From 2009 to 2018 based on Web of Science.

To find the trend and hot points of deafness gene research in the nearly 10 years, a bibliometric analysis of literature in the fields from Web of Science was performed. Python 3.7, Gephi 0.9.2, and SPSS 22.0 were used for cleaning, restructuring, and analysis. A total of 2828 article documents were collected, which were from 651 Science Citation Index Expanded journals, 93 countries/regions, 18 199 authors, and 3148 organizations. PLoS One published more papers than other journals. Among the journals that published more than 30 papers, 10 journals were included in the genetics & heredity class. The top country/region with highest number of papers was United States. However, the top author and top affiliation was Dai Pu (China) and People’s Liberate Army General Hospital (China), respectively. The results of co-occurrence network, hierarchical clustering, and multidimensional scale analysis of keywords showed that 2 groups were classified. The 2 groups focused on the gene mutation of deafness and the research objects, methods, factors, and gene locus, respectively. Multidimensional scale analysis told the research character and some research details. The gene mutation and variant of family and population diseases were the hot points.

Detection and Functional Verification of Noncanonical Splice Site Mutations in Hereditary Deafness.

Splice site mutations contribute to a significant portion of the genetic causes for mendelian disorders including deafness. By next-generation sequencing of 4 multiplex, autosomal dominant families and 2 simplex, autosomal recessive families with hereditary deafness, we identified a variety of candidate pathogenic variants in noncanonical splice sites of known deafness genes, which include c.1616+3A > T and c.580G > A in EYA4, c.322-57_322-8del in PAX3, c.991-15_991-13del in DFNA5, c.6087-3T > G in PTPRQ and c.164+5G > A in USH1G. All six variants were predicted to affect the RNA splicing by at least one of the computational tools Human Splicing Finder, NNSPLICE and NetGene2. Phenotypic segregation of the variants was confirmed in all families and is consistent with previously reported genotype-phenotype correlations of the corresponding genes. Minigene analysis showed that those splicing site variants likely have various negative impact including exon-skipping (c.1616+3A > T and c.580G > A in EYA4, c.991-15_991-13del in DFNA5), intron retention (c.322-57_322-8del in PAX3), exon skipping and intron retention (c.6087-3T > G in PTPRQ) and shortening of exon (c.164+5G > A in USH1G). Our study showed that the cryptic, noncanonical splice site mutations may play an important role in the molecular etiology of hereditary deafness, whose diagnosis can be facilitated by modified filtering criteria for the next-generation sequencing data, functional verification, as well as segregation, bioinformatics, and genotype-phenotype correlation analysis.

Identification and Computational Analysis of Rare Variants of Known Hearing Loss Genes Present in Five Deaf Members of a Pakistani Kindred.

Hearing loss (HL) is the most common neurosensory defect in humans that affects the normal communication. Disease is clinically and genetically heterogeneous, rendering challenges for the molecular diagnosis of affected subjects. This study highlights the phenotypic and genetic complexity of inherited HL in a large consanguineous Pakistan kindred. Audiological evaluation of all affected individuals revealed varying degree of mild to profound sensorineural HL. Whole exome (WES) of four family members followed by Sanger sequencing revealed candidate disease-associated variants in five known deafness genes: GJB2 (c.231G>A; p.(Trp77 *)), SLC26A4 (c.1337A>G; p.(Gln446Arg)), CDH23 (c.2789C>T; p.(Pro930Leu)), KCNQ4 (c.1672G>A; p.(Val558Met)) and MPDZ (c.4124T>C; p.(Val1375Ala)). All identified variants replaced evolutionary conserved residues, were either absent or had low frequencies in the control databases. Our in silico and 3-Dimensional (3D) protein topology analyses support the damaging impact of identified variants on the encoded proteins. However, except for the previously established “pathogenic” and “likely pathogenic” categories for the c.231G>A (p.(Trp77 *)) allele of GJB2 and c.1377A>G (p.(Gln446Arg)) of SLC26A4, respectively, all the remaining identified variants were classified as “uncertain significance” based on the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) variant pathogenicity guidelines. Our study highlights the complexity of genetic traits in consanguineous families, and the need of combining the functional studies even with the comprehensive profiling of multiple family members to improve the genetic diagnosis in complex inbred families.

DNA Marker Screening for High-Risk Non-syndromic Hearing Loss Associated to Gene Mutations

Background:Congenital hearing loss is a debilitating disease affecting 1–3 out of 1,000 live births. According to WHO’s associated figures, in both ears, 278 million people globally suffer from moderate to extreme hearing loss. Most hearing-loss individuals live in developing countries. Many deafness and hearing problems cases were documented in our region. Those cases’ exact cause is still unknown, so we performed this study and aimed to screen DNA in high-risk Non-syndromic hearing loss patients in Arbil city. Methods: This researchscreened 132 blood samples from (80 newborns and 52 individuals) at (Hiwa Institute for deaf and mutes); their ages patients from 14 to 22 years old.MTRNR1genes were performed for molecular detection of mutant genes. The mutation gene wasamplified by multiplex tetra primer PCR. Result:G- mito-1555-F1, mito-1555-R1 (O), mito-1555-F2 (I), and mito-1555-R2 (I) hearing loss mutations were not observed in 132 blood samples from both classes and genotyped in MTRNR1. For mtDNA 12S rRNA mt.1555A&gt;G, no mutant alleles were detected in all of the tests, and no false-positives were identified.Using all primers, fifty-two samples were easily separated on 2% agarose gel; two were outer primers, and others are inner primers. Two separate bands were observed with 52 molecular samples (wild type at 254bp and control at 341bp).Of 80 samples, 28 have control bands at 341 bp. We did not find any mutation in our 80 samples. Conclusion: MTRNR1 mutation genes were not present in collected samples in deafness-related mutation. Genetic tests for the deafness gene can better diagnose infant congenital NSHL cases than conventional screening procedures.