A Frameshift Variant in ANKRD24 Implicates Its Role in Human Non-Syndromic Hearing Loss.

Hearing loss (HL) is the most prevalent sensorineural disorders, affecting about one in 1000 newborns. Over half of the cases are attributed to genetic factors; however, due to the extensive clinical and genetic heterogeneity, many cases remain without a conclusive genetic diagnosis. The advent of next-generation sequencing methodologies in recent years has greatly helped unravel the genetic etiology of HL by identifying numerous genes and causative variants. Despite this, much remains to be uncovered about the genetic basis of sensorineural hearing loss (SNHL). Here, we report an Iranian consanguineous family with postlingual, moderate-to-severe autosomal recessive SNHL. After first excluding plausible variants in known deafness-causing genes using whole exome sequencing, we reanalyzed the data, using a gene/variant prioritization pipeline established for novel gene discovery for HL. This approach identified a novel homozygous frameshift variant c.1934_1937del; (p.Thr645Lysfs*52) in ANKRD24, which segregated with the HL phenotype in the family. Recently, ANKRD24 has been shown to be a pivotal constituent of the stereocilia rootlet in cochlea hair cells and interacts with TRIOBP, a protein already implicated in human deafness. Our data implicate for the first time, ANKRD24 in human nonsyndromic HL (NSHL) and expands the genetic spectrum of HL.

A Village in the Southeastern Region of Iran Harboring the c.716T>A (p.Val239Asp) Mutation in SLC26A4.

After GJB2, SLC26A4 is the second most common contributor to autosomal recessive nonsyndromic hearing loss (ARNSHL) worldwide. In this study, we used Exome Sequencing (ES) to present a village with 31 individuals affected by hereditary hearing loss (HHL) in southeastern Iran near the border of Pakistan. The village harbored the known pathogenic missense SLC26A4 (NM_000441.2):c.716T>A (p.Val239Asp) mutation, which has a founder effect attributed to Pakistan, Iran's southeastern neighbor. Our findings, in addition to unraveling the molecular cause of non-syndromic hearing loss in these patients and further confirming the common ancestry and migration story between the people of this region and Pakistan, provide further insight into the genetic background of this region and highlight the importance of understanding the mutation spectrum of GJB2 and SLC26A4 in different regions to choose cost-effective strategies for molecular genetic testing.

Novel PTPRQ variants associated with hearing loss in a Chinese family PTPRQ variants in Chinese hearing loss.

Introduction: Hearing loss is one of the most prevalent congenital sensory disorders. Over 50% of congenital hearing loss cases are attributed to genetic factors. The PTPRQ gene encodes the protein tyrosine phosphatase receptor Q, which plays an important role in maintaining the structure and function of the stereocilia of hair cells. Variants in the PTPRQ gene have been implicated in hereditary sensorineural hearing loss. Methods and Results: Utilizing next-generation sequencing technology, we identified novel compound heterozygous variants (c.977G>A:p.W326X and c.6742C>T:p.Q2248X) in the PTPRQ gene within a Chinese national lineage, marking the first association of these variants with hereditary sensorineural hearing loss. Discussion: Our findings further emphasize the critical role of PTPRQ in auditory function and contribute to a more comprehensive understanding of PTPRQ-associated hearing loss mechanisms, aiding in clinical management and genetic counseling.

A novel splice-altering TNC variant (c.5247A > T, p.Gly1749Gly) in an Chinese family with autosomal dominant non-syndromic hearing loss.

BACKGROUND: This study aims to analyze the pathogenic gene in a Chinese family with non-syndromic hearing loss and identify a novel mutation site in the TNC gene. METHODS: A five-generation Chinese family from Anhui Province, presenting with autosomal dominant non-syndromic hearing loss, was recruited for this study. By analyzing the family history, conducting clinical examinations, and performing genetic analysis, we have thoroughly investigated potential pathogenic factors in this family. The peripheral blood samples were obtained from 20 family members, and the pathogenic genes were identified through whole exome sequencing. Subsequently, the mutation of gene locus was confirmed using Sanger sequencing. The conservation of TNC mutation sites was assessed using Clustal Omega software. We utilized functional prediction software including dbscSNV_AdaBoost, dbscSNV_RandomForest, NNSplice, NetGene2, and Mutation Taster to accurately predict the pathogenicity of these mutations. Furthermore, exon deletions were validated through RT-PCR analysis. RESULTS: The family exhibited autosomal dominant, progressive, post-lingual, non-syndromic hearing loss. A novel synonymous variant (c.5247A > T, p.Gly1749Gly) in TNC was identified in affected members. This variant is situated at the exon-intron junction boundary towards the end of exon 18. Notably, glycine residue at position 1749 is highly conserved across various species. Bioinformatics analysis indicates that this synonymous mutation leads to the disruption of the 5' end donor splicing site in the 18th intron of the TNC gene. Meanwhile, verification experiments have demonstrated that this synonymous mutation disrupts the splicing process of exon 18, leading to complete exon 18 skipping and direct splicing between exons 17 and 19. CONCLUSION: This novel splice-altering variant (c.5247A > T, p.Gly1749Gly) in exon 18 of the TNC gene disrupts normal gene splicing and causes hearing loss among HBD families.

Low-intensity noise exposure takes an essential part in the mechanism of late-onset hereditary hearing loss caused by Abcc1 mutation.

With the development of the social economy, we are exposed to increasing noise in our daily lives. Our previous work found an ABCC1(NM_004996.3:c.A1769G, NP_004987.2:p.N590S) variant which cosegregated with the patients in an autosomal dominant non-syndromic hearing loss family. At present, the specific mechanism of deafness caused by ABCC1 mutation is still not clear. Using the knock-in mouse model simulating human ABCC1 mutation, we found that the occurrence of family-related phenotypes was likely attributed to the combination of the mouse genotype and low-intensity noise. GSH and GSSG are important physiological substrates of ABCC1. The destruction of GSH-GSSG balance in the cochleae of both Abcc1N591S/+ mice and Abcc1N591S/N591S mice during low-intensity noise exposure may result in irreversible damage to the hair cells of the cochleae, consequently leading to hearing loss in mice. The findings offered a potential novel idea for the prevention and management of hereditary hearing loss within this family.

Whole Exome Sequencing of Non-Syndromic Hearing Loss Patients.

Background: Hearing loss is the second most common disease after mental retardation in Iran. Autosomal recessive non-syndromic hearing loss (ARNSHL) is an extreme and highly heterogeneous disease, for which more than 70 genes have been identified. Considering the frequency of family marriage as well as the importance of ARNSHL in Iran, we evaluated the genetic factors involved in this type of deafness. Methods: We performed the whole exome sequencing (WES) of eight Iranian subjects with severe nonsyndromic hearing loss selected from 110 well-characterized subjects with non-syndromic hearing loss from 2017-2019. The patients with mutated GJB2 and GJB6 genes were excluded from the study. Results: The use of the whole exome sequencing method revealed 10 different mutations in 7 genes, including SLC26A4 (c.1234G>T), FGF3 (c.45DelC, c.466T>C), ADGRV1 (c.12528-2A>C, c.16226-16227insAGTC), OTOG (c.7454delG), OTOF (c.3570+2T>C), ESPN (c.992G>A), OTOA (c.2359G>T, c.2353A>C). Seven new variants were observed in seven families including SLC26A4 (c.1234G>T), FGF3 (c.45DelC), ADGRV1 (c.12528-2A>C), OTOG (c.7454delG), ADGRV1 (c.16226-16227insAGTC), OTOF (c.3570+2T>C). Conclusion: The causal mutation of ARNSHL was found in all patients using the WES. Meta-analysis studies can help to identify common mutations causing deafness in any population to facilitate identification of carriers and subjects with deafness.

Comprehensive Genetic Evaluation in Patients with Special Reference to Late-Onset Sensorineural Hearing Loss.

Hearing loss (HL) is a common and multi-complex etiological deficit that can occur at any age and can be caused by genetic variants, aging, toxic drugs, noise, injury, viral infection, and other factors. Recently, a high incidence of genetic etiologies in congenital HL has been reported, and the usefulness of genetic testing has been widely accepted in congenital-onset or early-onset HL. In contrast, there have been few comprehensive reports on the relationship between late-onset HL and genetic causes. In this study, we performed next-generation sequencing analysis for 91 HL patients mainly consisting of late-onset HL patients. As a result, we identified 23 possibly disease-causing variants from 29 probands, affording a diagnostic rate for this study of 31.9%. The highest diagnostic rate was observed in the congenital/early-onset group (42.9%), followed by the juvenile/young adult-onset group (31.7%), and the middle-aged/aged-onset group (21.4%). The diagnostic ratio decreased with age; however, genetic etiologies were involved to a considerable degree even in late-onset HL. In particular, the responsible gene variants were found in 19 (55.9%) of 34 patients with a familial history and progressive HL. Therefore, this phenotype is considered to be a good candidate for genetic evaluation based on this diagnostic panel.

Hearing Loss in Baraitser-Winter Syndrome: Case Reports and Review of the Literature.

Background: Baraitser-Winter Syndrome (BRWS) is a rare autosomal dominant condition associated with hearing loss (HL). In the literature, two types of this condition are reported, Baraitser-Winter type 1 (BRWS1) and type 2 (BRWS2) produced by specific pathogenetic variants of two different genes, ACTB for BRWS1 and ACTG1 for BRWS2. In addition to syndromic BRWS2, some pathogenic variants in ACTG1 are associated also to another pathologic entity, the "Autosomal dominant non-syndromic hearing loss 20/26". In these syndromes, typical craniofacial features, sensory impairment (vision and hearing) and intellectual disabilities are frequently present. Heart anomalies, renal and gastrointestinal involvement and seizure are also common. Wide inter- and intra-familial variety in the phenotypic spectrum is reported. Some phenotypic aspects of these syndromes are not yet fully described, such as the degree and progression of HL, and better knowledge of them could be useful for correct follow-up and treatment. Methods and Results: In this study, we report two cases of children with HL and diagnosis of BRWS and a review of the current literature on HL in these syndromes.

Detailed Clinical Features of PTPRQ-Associated Hearing Loss Identified in a Large Japanese Hearing Loss Cohort.

The PTPRQ gene has been identified as one of the genes responsible for non-syndromic sensorineural hearing loss (SNHL), and assigned as DFNA73 and DFNB84. To date, about 30 causative PTPRQ variants have been reported to cause SNHL. However, the detailed clinical features of PTPRQ-associated hearing loss (HL) remain unclear. In this study, 15,684 patients with SNHL were enrolled and genetic analysis was performed using massively parallel DNA sequencing (MPS) for 63 target deafness genes. We identified 17 possibly disease-causing PTPRQ variants in 13 Japanese patients, with 15 of the 17 variants regarded as novel. The majority of variants identified in this study were loss of function. Patients with PTPRQ-associated HL mostly showed congenital or childhood onset. Their hearing levels at high frequency deteriorated earlier than that at low frequency. The severity of HL progressed from moderate to severe or profound HL. Five patients with profound or severe HL received cochlear implantation, and the postoperative sound field threshold levels and discrimination scores were favorable. These findings will contribute to a greater understanding of the clinical features of PTPRQ-associated HL and may be relevant in clinical practice.

Demographic analysis of hearing impairment based on various parameters in patients with cochlear implant.

Objectives: To analyse the demographic and clinical variables in children having undergone cochlear implant surgery because of deafness. METHODS: The cross-sectional study was conducted from January to November 2022 at the Centre for Research in Experimental and Applied Medicine laboratory of the Department of Biochemistry and Molecular Biology, Army Medical College, Rawalpindi, Pakistan, in collaboration with the Ear, Nose and Throat Department of Combined Military Hospital, Rawalpindi, and comprised children of eith gender aged up to 10 years who had received cochlear implant. Data was collected through questionnaire-based detailed interviews. Syndromic Hearing Loss, Non-Syndromic Hearing Loss, and Acquired Hearing Loss were identified among the subjects. Data was analysed using SPSS 22. RESULTS: Of the 250 cases, 147(58.8%) were boys, 146(58.4%) were aged 0-5 years, 219(87.6%) had prelingual onset of disease, and 202(80.8%) had a non-progressive disease course. In 203(81.2%) cases, normal developmental milestones were seen. Parental consanguinity was observed in 219(87.6%) cases. However, 63(25.2%) patients had a first-degree relative who had a history of deafness. In 170(68%) cases, hearing loss was hereditary, whereas in 80(32%) it was acquired. Meningitis was the most commonly identified risk factor 55(68.75%). Acquired risk factors and family history had significant association with hearing loss (p<0.05). Speech perception significantly improved in all 219(100%) patients with prelingual hearing loss who underwent cochlear implantation. CONCLUSIONS: Majority of the cases were found to be male, had a prelingual disease onset and a non-progressive disease course. Family history was a significant factor, while meningitis was the most common acquired cause of hearing loss.

Autosomal recessive non-syndromic hearing loss genes in Pakistan during the previous three decades.

Hearing loss is a clinically and genetically heterogeneous disorder, with over 148 genes and 170 loci associated with its pathogenesis. The spectrum and frequency of causal variants vary across different genetic ancestries and are more prevalent in populations that practice consanguineous marriages. Pakistan has a rich history of autosomal recessive gene discovery related to non-syndromic hearing loss. Since the first linkage analysis with a Pakistani family that led to the mapping of the DFNB1 locus on chromosome 13, 51 genes associated with this disorder have been identified in this population. Among these, 13 of the most prevalent genes, namely CDH23, CIB2, CLDN14, GJB2, HGF, MARVELD2, MYO7A, MYO15A, MSRB3, OTOF, SLC26A4, TMC1 and TMPRSS3, account for more than half of all cases of profound hearing loss, while the prevalence of other genes is less than 2% individually. In this review, we discuss the most common autosomal recessive non-syndromic hearing loss genes in Pakistani individuals as well as the genetic mapping and sequencing approaches used to discover them. Furthermore, we identified enriched gene ontology terms and common pathways involved in these 51 autosomal recessive non-syndromic hearing loss genes to gain a better understanding of the underlying mechanisms. Establishing a molecular understanding of the disorder may aid in reducing its future prevalence by enabling timely diagnostics and genetic counselling, leading to more effective clinical management and treatments of hearing loss.

Novel compound heterozygous MYO15A splicing variants in autosomal recessive non-syndromic hearing loss.

BACKGROUND: Hereditary hearing loss is a highly heterogeneous disorder. This study aimed to identify the genetic cause of a Chinese family with autosomal recessive non-syndromic sensorineural hearing loss (ARNSHL). METHODS: Clinical information and peripheral blood samples were collected from the proband and its parents. Two-step high-throughput next-generation sequencing on the Ion Torrent platform was applied to detect variants as follows. First, long-range PCR was performed to amplify all the regions of the GJB2, GJB3, SLC26A4, and MT-RNR1 genes, followed by next-generation sequencing. If no candidate pathogenetic variants were found, the targeted exon sequencing with AmpliSeq technology was employed to examine another 64 deafness-associated genes. Sanger sequencing was used to identify variants and the lineage co-segregation. The splicing of the MYO15A gene was assessed by in silico bioinformatics prediction and minigene assays. RESULTS: Two candidate MYO15A gene (OMIM, #602,666) heterozygous splicing variants, NG_011634.2 (NM_016239.3): c.6177 + 1G > T and c.9690 + 1G > A, were identified in the proband, and these two variants were both annotated as pathogenic according to the American College of Medical Genetics and Genomics (ACMG) guidelines. Further bioinformatic analysis predicted that the c.6177 + 1G > T variant might cause exon skipping and that the c.9690 + 1G > A variant might activate a cryptic splicing donor site in the downstream intronic region. An in vitro minigene assay confirmed the above predictions. CONCLUSIONS: We identified a compound heterozygous splicing variant in the MYO15A gene in a Han Chinese family with ARNSHL. Our results broaden the spectrum of MYO15A variants, potentially benefiting the early diagnosis, prevention, and treatment of the disease.

Mutation analysis of GJB2, SLC26A4, GJB3 and mtDNA12SrRNA genes in 251 non-syndromic hearing loss patients in Fujian, China.

OBJECTIVES: The molecular etiology of non-syndromic hearing loss (NSHL) in Southeastern China (Fujian) has not been precisely identified. our study selected patients with NSHL and analyzed their causative genes, which helped to improve the accuracy of the diagnosis of hereditary hearing loss (HHL) and its treatment. METHODS: 251 unrelated patients who attended the otolaryngology clinic of Fujian Maternal and Child Health Hospital with hearing loss were enrolled to our study. All patients had genetic tests and listening tests, of which 251 were diagnosed with NSHL. In addition, we used whole-exome sequencing (WES) in a patient who has a significant family history of HHL but negative for gene chip testing, as well as in his family members. RESULT: Among of 251 patients, Nucleotide changes were found in 63 cases (25.09%), including 34 located in GJB2(13.5%, including 235delC and 299_300delAT), 13 located in SLC26A4(5.18%, including c.919-2G > A and 2168 A > G), 1 located in GJB3(0.4%,538C > T) and 16 located in mtDNA12SrRNA (6.37%,1555 A > G). In addition, we discuss the process of identifying novel PLS1 mutations from 251 patients. CONCLUSION: Our results demonstrate the conventional deafness gene mutation in 251 NSHL patients in Fujian, China. Compared with the other area of China, we have a lower detection rate, but GJB2 235delC remains the most common mutation in Fujian. In addition, we discuss the process of discovering novel mutation locus for deafness, which provides an understanding for deafness diagnosis and genetic testing.

A Descriptive Observational Study of GJB2 and GJB6 Mutations in Familial Autosomal Recessive Non-syndromic Hearing Impairment.

Mutations in the genes, GJB2 and GJB6 play an important role in autosomal recessive, non-syndromic hearing loss. This study is aimed to detect the association of mutations in GJB2 and GJB6 genes in familial autosomal recessive non-syndromic hearing impairment cases. We included 26 families with at least two affected individuals having congenital bilateral, non-syndromic sensorineural hearing loss. Blood samples were drawn, DNA was extracted, and sent for multiplex PCR and Sanger sequencing. Of the 26 families analyzed, GJB2 mutations were detected in 9(34.6%) and GJB6 mutations were not detected in any of the families. GJB2 mutations are a major cause of congenital, non-syndromic hearing loss in this study population. This study also suggests that GJB6 mutations do not contribute to autosomal recessive non-syndromic hearing loss in the Indian population.

Non-Syndromic Sensorineural Hearing Loss in Children.

Pediatric hearing loss is common with significant consequences in terms of language, communication, social and emotional development, and academic advancement. Radiological imaging provides useful information regarding hearing loss etiology, prognosis, therapeutic options, and potential surgical pitfalls. This review provides an overview of temporal bone imaging protocols, an outline of the classification of inner ear anomalies associated with sensorineural hearing loss and illustrates some of the more frequently encountered and/or important causes of non-syndromic hearing loss.

Autosomal dominant non-syndromic hearing loss caused by a novel mutation in MYO7A: A case report and review of the literature.

BACKGROUND: Variants in the MYO7A gene commonly result in Usher syndrome, and in rare cases lead to autosomal dominant non-syndromic deafness (DFNA11). Currently, only nine variants have been reported to be responsible for DFNA11 and their clinical phenotypes are not identical. Here we present a novel variant causing DFNA11 identified in a three-generation Chinese family. CASE SUMMARY: The proband was a 53-year-old Han male who presented with post-lingual bilateral symmetrical moderate sensorineural hearing loss. We learned from the patient's medical history collection that multiple family members also had similar hearing loss, generally occurring around the age of 40. Subsequent investigation by high-throughput sequencing identified a novel MYO7A variant. To provide evidence supporting that this variant is responsible for the hearing loss in the studied family, we performed Sanger sequencing on 11 family members and found that the variant co-segregated with the deafness phenotype. In addition, the clinical manifestation of the 11 affected family members was found to be late-onset bilateral slowly progressive hearing loss, inherited in this family in an autosomal dominant manner. None of the affected family members had visual impairment or vestibular symptoms; therefore, we believe that this novel MYO7A variant is responsible for the rare DFNA11 in this family. CONCLUSION: We report a novel variant leading to DFNA11 which further enriches the collection of MYO7A variants, and our review of the nine previous variants that have been identified to cause DFNA11 provides a reference for clinical genetic counseling.

An Extended Iranian Family with Autosomal Dominant Non-syndromic Hearing Loss Associated with A Nonsense Mutation in the DIAPH1 Gene.

Genetic analysis of non-syndromic hearing loss (NSHL) has been challenged due to marked clinical and genetic heterogeneity. Today, advanced next-generation sequencing (NGS) technologies, such as exome sequencing (ES), have drastically increased the efficacy of gene identification in heterogeneous Mendelian disorders. Here, we present the utility of ES and re-evaluate the phenotypic data for identifying candidate causal variants for previously unexplained progressive moderate to severe NSHL in an extended Iranian family. Using this method, we identified a known heterozygous nonsense variant in exon 26 of the DIAPH1 gene (MIM: 602121), which led to "Deafness, autosomal dominant 1, with or without thrombocytopenia; DFNA1" (MIM: 124900) in this large family in the absence of GJB2 disease-causing variants and also OtoSCOPE-negative results. To the best of our knowledge, this nonsense variant (NM_001079812.3):c.3610C>T (p.Arg1204Ter) is the first report of the DIAPH1 gene variant for autosomal dominant non-syndromic hearing loss (ADNSHL) in Iran.

Genotype-Phenotype Correlations in TMPRSS3 (DFNB10/DFNB8) with Emphasis on Natural History.

BACKGROUND: Mutations in TMPRSS3 are an important cause of autosomal recessive non-syndromic hearing loss. The hearing loss associated with mutations in TMPRSS3 is characterized by phenotypic heterogeneity, ranging from mild to profound hearing loss, and is generally progressive. Clinical presentation and natural history of TMPRSS3 mutations vary significantly based on the location and type of mutation in the gene. Understanding these genotype-phenotype relationships and associated natural disease histories is necessary for the successful development and application of gene-based therapies and precision medicine approaches to DFNB8/10. The heterogeneous presentation of TMPRSS3-associated disease makes it difficult to identify patients clinically. As the body of literature on TMPRSS3-associated deafness grows, there is need for better categorization of the hearing phenotypes associated with specific mutations in the gene. SUMMARY: In this review, we summarize TMPRSS3 genotype-phenotype relationships including a thorough description of the natural history of patients with TMPRSS3-associated hearing loss to lay the groundwork for the future of TMPRSS3 treatment using molecular therapy. KEY MESSAGES: TMPRSS3 mutation is a significant cause of genetic hearing loss. All patients with TMPRSS3 mutation display severe-to-profound prelingual (DFNB10) or a postlingual (DFNB8) progressive sensorineural hearing loss. Importantly, TMPRSS3 mutations have not been associated with middle ear or vestibular deficits. The c.916G>A (p.Ala306Thr) missense mutation is the most frequently reported mutation across populations and should be further explored as a target for molecular therapy.

Autosomal Dominant Non-Syndromic Hearing Loss (DFNA): A Comprehensive Narrative Review.

Autosomal dominant non-syndromic hearing loss (HL) typically occurs when only one dominant allele within the disease gene is sufficient to express the phenotype. Therefore, most patients diagnosed with autosomal dominant non-syndromic HL have a hearing-impaired parent, although de novo mutations should be considered in all cases of negative family history. To date, more than 50 genes and 80 loci have been identified for autosomal dominant non-syndromic HL. DFNA22 (MYO6 gene), DFNA8/12 (TECTA gene), DFNA20/26 (ACTG1 gene), DFNA6/14/38 (WFS1 gene), DFNA15 (POU4F3 gene), DFNA2A (KCNQ4 gene), and DFNA10 (EYA4 gene) are some of the most common forms of autosomal dominant non-syndromic HL. The characteristics of autosomal dominant non-syndromic HL are heterogenous. However, in most cases, HL tends to be bilateral, post-lingual in onset (childhood to early adulthood), high-frequency (sloping audiometric configuration), progressive, and variable in severity (mild to profound degree). DFNA1 (DIAPH1 gene) and DFNA6/14/38 (WFS1 gene) are the most common forms of autosomal dominant non-syndromic HL affecting low frequencies, while DFNA16 (unknown gene) is characterized by fluctuating HL. A long audiological follow-up is of paramount importance to identify hearing threshold deteriorations early and ensure prompt treatment with hearing aids or cochlear implants.

Loss-of-function mutations in MYO15A and OTOF cause non-syndromic hearing loss in two Yemeni families.

BACKGROUND: Hearing loss is a rare hereditary deficit that is rather common among consanguineous populations. Autosomal recessive non-syndromic hearing loss is the predominant form of hearing loss worldwide. Although prevalent, hearing loss is extremely heterogeneous and poses a pitfall in terms of diagnosis and screening. Using next-generation sequencing has enabled a rapid increase in the identification rate of genes and variants in heterogeneous conditions, including hearing loss. We aimed to identify the causative variants in two consanguineous Yemeni families affected with hearing loss using targeted next-generation sequencing (clinical exome sequencing). The proband of each family was presented with sensorineural hearing loss as indicated by pure-tone audiometry results. RESULTS: We explored variants obtained from both families, and our analyses collectively revealed the presence and segregation of two novel loss-of-function variants: a frameshift variant, c.6347delA in MYO15A in Family I, and a splice site variant, c.5292-2A > C, in OTOF in Family II. Sanger sequencing and PCR-RFLP of DNA samples from 130 deaf and 50 control individuals confirmed that neither variant was present in our in-house database. In silico analyses predicted that each variant has a pathogenic effect on the corresponding protein. CONCLUSIONS: We describe two novel loss-of-function variants in MYO15A and OTOF that cause autosomal recessive non-syndromic hearing loss in Yemeni families. Our findings are consistent with previously reported pathogenic variants in the MYO15A and OTOF genes in Middle Eastern individuals and suggest their implication in hearing loss.