scholarly journals Genomic analysis of childhood hearing loss in the Yoruba population of Nigeria

2021 ◽  
Author(s):  
Adebolajo Adeyemo ◽  
Rabia Faridi ◽  
Parna Chattaraj ◽  
Rizwan Yousaf ◽  
Risa Tona ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Molecular Genetic ◽  
Usher Syndrome ◽  
Sensorineural Deafness ◽  
Genomic Analysis ◽  
Nonsyndromic Hearing Loss ◽  
Pathogenic Variants ◽  
Causal Variants ◽  
High Level ◽  
Ibadan Nigeria

AbstractAlthough variant alleles of hundreds of genes are associated with sensorineural deafness in children, the genes and alleles involved remain largely unknown in the Sub-Saharan regions of Africa. We ascertained 56 small families mainly of Yoruba ethno-lingual ancestry in or near Ibadan, Nigeria, that had at least one individual with nonsyndromic, severe-to-profound, prelingual-onset, bilateral hearing loss not attributed to nongenetic factors. We performed a combination of exome and Sanger sequencing analyses to evaluate both nuclear and mitochondrial genomes. No biallelic pathogenic variants were identified in GJB2, a common cause of deafness in many populations. Potential causative variants were identified in genes associated with nonsyndromic hearing loss (CIB2, COL11A1, ILDR1, MYO15A, TMPRSS3, and WFS1), nonsyndromic hearing loss or Usher syndrome (CDH23, MYO7A, PCDH15, and USH2A), and other syndromic forms of hearing loss (CHD7, OPA1, and SPTLC1). Several rare mitochondrial variants, including m.1555A>G, were detected in the gene MT-RNR1 but not in control Yoruba samples. Overall, 20 (33%) of 60 independent cases of hearing loss in this cohort of families were associated with likely causal variants in genes reported to underlie deafness in other populations. None of these likely causal variants were present in more than one family, most were detected as compound heterozygotes, and 77% had not been previously associated with hearing loss. These results indicate an unusually high level of genetic heterogeneity of hearing loss in Ibadan, Nigeria and point to challenges for molecular genetic screening, counseling, and early intervention in this population.

scholarly journals Analysis of the mutational spectrum of the SLC26A4 gene and its contribution to the etiology of inherited hearing loss in the indigenous population of Southern Siberia

2020 ◽  
pp. 43-45
Author(s):  
В.Ю. Данильченко ◽  
М.В. Зыцарь ◽  
Е.А. Маслова ◽  
М.С. Бады-Хоо ◽  
И.В. Морозов ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Unknown Etiology ◽  
Southern Siberia ◽  
Pathogenic Variants ◽  
Slc26a4 Gene ◽  
Wide Range ◽  
Polymorphic Variants ◽  
Tyva Republic

Мутации в гене SLC26A4 являются частой причиной потери слуха во многих регионах мира. В работе приводятся результаты молекулярно-генетического анализа (с использованием секвенирования по Сэнгеру) последовательности гена SLC26A4, впервые проведенного в выборке пациентов с потерей слуха неустановленной этиологии (n=232) из Республик Тыва и Алтай. Установлены контрастные различия патогенетического вклада мутаций в гене SLC26A4 в этиологию нарушения слуха у коренных жителей этих географически близких регионов: 28,2% - для тувинцев и 4,3% - для алтайцев. Выявлены как уже известные, так и новые патогенные варианты, а также широкий спектр полиморфных вариантов гена SLC26A4. Mutations in the SLC26A4 gene are a common cause of hearing loss in many regions of the world. This paper presents the results of molecular genetic analysis (by Sanger sequencing) of the SLC26A4 sequence, first performed in the sample of patients with hearing loss of unknown etiology (n=232) from the Tyva Republic and the Altai Republic. Contrast differences of the pathogenic contribution of SLC26A4 mutations to the etiology of hearing impairment were revealed in the indigenous peoples of these geographically close regions: 28.2% for Tuvinians and 4.3% for Altaians. Both known and novel pathogenic variants as well as a wide range of polymorphic variants were found in the SLC26A4 gene sequence.

scholarly journals Identification of Novel CDH23 Variants Causing Moderate to Profound Progressive Nonsyndromic Hearing Loss

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1474
Author(s):  
Khushnooda Ramzan ◽  
Nouf S. Al-Numair ◽  
Sarah Al-Ageel ◽  
Lina Elbaik ◽  
Nadia Sakati ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Phenotypic Variability ◽  
Usher Syndrome ◽  
Three Dimensional ◽  
Homozygosity Mapping ◽  
Dimensional Structure ◽  
Molecular Testing ◽  
Compound Heterozygous ◽  
Nonsyndromic Hearing Loss ◽  
Missense Variants

Mutant alleles of CDH23, a gene that encodes a putative calcium-dependent cell-adhesion glycoprotein with multiple cadherin-like domains, are responsible for both recessive DFNB12 nonsyndromic hearing loss (NSHL) and Usher syndrome 1D (USH1D). The encoded protein cadherin 23 (CDH23) plays a vital role in maintaining normal cochlear and retinal function. The present study’s objective was to elucidate the role of DFNB12 allelic variants of CDH23 in Saudi Arabian patients. Four affected offspring of a consanguineous family with autosomal recessive moderate to profound NSHL without any vestibular or retinal dysfunction were investigated for molecular exploration of genes implicated in hearing impairment. Parallel to this study, we illustrate some possible pitfalls that resulted from unexpected allelic heterogeneity during homozygosity mapping due to identifying a shared homozygous region unrelated to the disease locus. Compound heterozygous missense variants (p.(Asp918Asn); p.(Val1670Asp)) in CDH23 were identified in affected patients by exome sequencing. Both the identified missense variants resulted in a substitution of the conserved residues and evaluation by multiple in silico tools predicted their pathogenicity and variable disruption of CDH23 domains. Three-dimensional structure analysis of human CDH23 confirmed that the residue Asp918 is located at a highly conserved DXD peptide motif and is directly involved in “Ca2+” ion contact. In conclusion, our study identifies pathogenic CDH23 variants responsible for isolated moderate to profound NSHL in Saudi patients and further highlights the associated phenotypic variability with a genotypic hierarchy of CDH23 mutations. The current investigation also supports the application of molecular testing in the clinical diagnosis and genetic counseling of hearing loss.

scholarly journals Novel Loss-of-Function Mutations in COCH Cause Autosomal Recessive Nonsyndromic Deafness

2020 ◽  
Author(s):  
Kevin T Booth ◽  
Amama Ghaffar ◽  
Muhammad Rashid ◽  
Luke T Hovey ◽  
Mureed Hussain ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Rna Splicing ◽  
Autosomal Recessive ◽  
Dominant Negative ◽  
Nonsyndromic Hearing Loss ◽  
Loss Of Function ◽  
Functional Studies ◽  
Pathogenic Variants ◽  
Exon Splicing ◽  
Coding Variants

AbstractCOCH is the most abundantly expressed gene in the cochlea. Unsurprisingly, mutations in COCH underly deafness in mice and humans. Two forms of deafness are linked to mutations in COCH, the well-established autosomal dominant nonsyndromic hearing loss, with or without vestibular dysfunction (DFNA9) via a gain-of-function/dominant-negative mechanism, and more recently autosomal recessive nonsyndromic hearing loss (DFNB110) via nonsense variants. Using a combination of targeted gene panels, exome sequencing and functional studies, we identified four novel pathogenic variants (two nonsense variants, one missense and one inframe deletion) in COCH as the cause of autosomal recessive hearing loss in a multi-ethnic cohort. To investigate whether the non-truncating variants exert their effect via a loss-of-function mechanism, we used mini-gene splicing assays. Our data showed both the missense and inframe deletion variants altered RNA-splicing by creating an exon splicing silencer and abolishing an exon splicing enhancer, respectively. Both variants create frameshifts and are predicted to result in a null allele. This study confirms the involvement of loss-of-function mutations in COCH in autosomal recessive nonsyndromic hearing loss, expands the mutational landscape of DFNB110 to include coding variants that alter RNA-splicing, and highlights the need to investigate the effect of coding variants on RNA-splicing.

Mutation Analysis of the Common Deafness Genes in Patients with Nonsyndromic Hearing Loss in Republic of Macedonia

2017 ◽  
Vol 71 (1) ◽  
pp. 20-26
Author(s):  
Emilija Sukarova Stefanovska ◽  
Gjorgji Bozhinovski ◽  
Ana Momirovska ◽  
Marina Davceva Cakar ◽  
Elena Sukarova-Angelovska ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Modifier Gene ◽  
Compound Heterozygous ◽  
Nonsyndromic Hearing Loss ◽  
Allelic Variants ◽  
Republic Of Macedonia ◽  
Pathogenic Variants ◽  
Molecular Etiology ◽  
The Common ◽  
The Republic

Abstract Hearing impairment is the most common sensory disorder, which occurs in 1 of 1000 newborns. It is caused by heterogeneous conditions with more than a half due to genetic etiology. Although hundreds of genes are implicated in hearing process and have been found to be associated with nonsyndromic hearing loss, pathogenic variants in GJB2 gene have been considered as the main cause of deafness among nonsyndromic hearing loss (NSHL) population worldwide. Pathogenic variants in MT-RNR1 or mtDNA12SrRNA gene were also implicated predominantly in postlingual progresive deafness. The aim of this study was to analyze the implication of GJB2 and MT-RNR1 genes in the molecular etiology of deafness among 130 NSHL patients in the Republic of Macedonia. The presence of the del (GJB6-D13S1830) was also analysed. We performed SSCP and/or sequence analysis of GJB2 and identified sequence variants in 62 out of 130 patients (47.7%); (51 homozygous or compound heterozygous and 11 with only one variant allele). We found 8 different allelic variants, the most prevalent being c.35delG (65.49%), and p.W24*(23.01%), followed by other less frequent alleles (p.V27I, p.V37I, p. P175T and cd. delE120 or delGAG at 360). In addition, two polymorphic substitutions in the GJB2 gene with no clinical significance (p.V153I and p.R127H) were detected. No del(GJB6-D13S1830) was found. SNaPshot analysis was used to screen for the five most frequent allelic variants in the MT-RNR1 gene. Two MT-RNR1 mutations (A827G and T961G) were detected in three patients where only one GJB2 pathogenic variant was found. A new MT-RNR1 gene variant G1303A was also detected. In conclusion, MT-RNR1 mutations were not a significant contributor to the etiology of deafness in Macedonia, although could be considered as a modifier gene affecting the expression of deafness in patients carrying one GJB2 variant. On the other hand, the high percenttage of GJB2 pathogenic variants identified among NSHL cases indicates the necessity of molecular newborn screening for the two most common GJB2 variants (c.35delG and p.W24*) in the Republic of Macedonia.

scholarly journals Genetic Spectrum of Syndromic and Non-Syndromic Hearing Loss in Pakistani Families

Genes ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1329
Author(s):  
Julia Doll ◽  
Barbara Vona ◽  
Linda Schnapp ◽  
Franz Rüschendorf ◽  
Imran Khan ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Exome Sequencing ◽  
Splice Site ◽  
Genetic Heterogeneity ◽  
Bioinformatics Analysis ◽  
Molecular Genetic ◽  
Compound Heterozygous ◽  
Pathogenic Variants ◽  
Syndromic Hearing Loss ◽  
Pakistani Families

The current molecular genetic diagnostic rates for hereditary hearing loss (HL) vary considerably according to the population background. Pakistan and other countries with high rates of consanguineous marriages have served as a unique resource for studying rare and novel forms of recessive HL. A combined exome sequencing, bioinformatics analysis, and gene mapping approach for 21 consanguineous Pakistani families revealed 13 pathogenic or likely pathogenic variants in the genes GJB2, MYO7A, FGF3, CDC14A, SLITRK6, CDH23, and MYO15A, with an overall resolve rate of 61.9%. GJB2 and MYO7A were the most frequently involved genes in this cohort. All the identified variants were either homozygous or compound heterozygous, with two of them not previously described in the literature (15.4%). Overall, seven missense variants (53.8%), three nonsense variants (23.1%), two frameshift variants (15.4%), and one splice-site variant (7.7%) were observed. Syndromic HL was identified in five (23.8%) of the 21 families studied. This study reflects the extreme genetic heterogeneity observed in HL and expands the spectrum of variants in deafness-associated genes.

Genetic Epidemiology of Mitochondrial Pathogenic Variants Causing Nonsyndromic Hearing Loss in a Large Cohort of South Indian Hearing Impaired Individuals

2016 ◽  
Vol 80 (5) ◽  
pp. 257-273 ◽  
Author(s):  
Mahalingam Subathra ◽  
Arabandi Ramesh ◽  
Mathiyalagan Selvakumari ◽  
N. P. Karthikeyen ◽  
C. R. Srikumari Srisailapathy
Keyword(s):  
Hearing Loss ◽  
Genetic Epidemiology ◽  
Hearing Impaired ◽  
Large Cohort ◽  
Nonsyndromic Hearing Loss ◽  
Pathogenic Variants ◽  
South Indian

scholarly journals Comprehensive molecular-genetic analysis of mid-frequency sensorineural hearing loss

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zuzana Pavlenkova ◽  
Lukas Varga ◽  
Silvia Borecka ◽  
Miloslav Karhanek ◽  
Miloslava Huckova ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Genetic Disorder ◽  
Molecular Genetic ◽  
Molecular Genetic Analysis ◽  
Sensorineural Hearing ◽  
Variant Of Uncertain Significance ◽  
Pathogenic Variants ◽  
Causal Genes ◽  
Uncertain Significance

AbstractThe genetic heterogeneity of sensorineural hearing loss (SNHL) is a major hurdle to the detection of disease-causing variants. We aimed to identify underlying causal genes associated with mid-frequency hearing loss (HL), which contributes to less than about 1% of SNHL cases, by whole exome sequencing (WES). Thirty families segregating mid-frequency SNHL, in whom biallelic GJB2 mutations had been previously excluded, were selected from among 851 families in our DNA repository of SNHL. DNA samples from the probands were subjected to WES analysis and searched for candidate variants associated with SNHL. We were able to identify the genetic aetiology in six probands (20%). In total, we found three pathogenic and three likely pathogenic variants in four genes (COL4A5, OTOGL, TECTA, TMPRSS3). One more proband was a compound heterozygote for a pathogenic variant and a variant of uncertain significance (VUS) in MYO15A gene. To date, MYO15A and TMPRSS3 have not yet been described in association with mid-frequency SNHL. In eight additional probands, eight candidate VUS variants were detected in five genes (DIAPH1, MYO7A, TECTA, TMC1, TSPEAR). Seven of these 16 variants have not yet been published or mentioned in the available databases. The most prevalent gene was TECTA, identified in 23% of all tested families. Furthermore, we confirmed the hypothesis that a substantive portion of cases with this conspicuous audiogram shape is a consequence of a genetic disorder.

scholarly journals A novel USH2A variant in a patient with hearing loss and prenatal diagnosis of a familial fetus: a case report

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Cong Zhou ◽  
Yuanyuan Xiao ◽  
Hanbing Xie ◽  
Shanling Liu ◽  
Jing Wang
Keyword(s):  
Hearing Loss ◽  
Prenatal Diagnosis ◽  
Usher Syndrome ◽  
Chinese Patient ◽  
Compound Heterozygous ◽  
Case Presentation ◽  
Pathogenic Variants ◽  
Compound Heterozygous Variants ◽  
Gene Panels

Abstract Background Usher syndrome (USH) is the most common cause of inherited deaf-blindness. The current study aimed to identify pathogenic variants in a Chinese patient with hearing loss and to report the identification of a novel p.(Phe1583Leufs*10) variant in USH2A, which met the needs of prenatal diagnosis of the patient's mother. Case presentation Genomic DNA obtained from a five-year-old girl with hearing loss was analyzed via the hearing loss-targeted gene panels. We identified the compound heterozygous variants c.8559-2A>G and c.4749delT in Usher syndrome type 2A (USH2A) gene as the underlying cause of the patient; the former variation has been reported in the literature, but not the latter. The parents of the girl were heterozygous carriers. The two variants were classified as pathogenic. Based on these findings, amniotic fluid samples were used for prenatal diagnosis of the couple's fetus, which was found to carry c.4749delT but not c.8559-2A>G variation. During the follow-up period of more than 9 months after the birth of the fetus, it was confirmed that the infant was healthy. Conclusions The results of the present study identified two compound heterozygous USH2A variants in a patient with hearing loss and reported a novel USH2A variant which expands the spectrum of USH2A variants in USH.

scholarly journals Association of a novel missense mutation in MYO15A with nonsyndromic hearing loss: a case report

2020 ◽  
Author(s):  
Siji Wang ◽  
Ziqi Chen ◽  
Jiaqiu Dai ◽  
Xi Ouyang ◽  
Lin Zhu ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Missense Mutation ◽  
Sanger Sequencing ◽  
Three Dimensional ◽  
Sensorineural Deafness ◽  
Chinese Family ◽  
Common Disease ◽  
Compound Heterozygous ◽  
Nonsyndromic Hearing Loss ◽  
Genetic Sequencing

Abstract Background Hearing loss is a common disease globally, and more than 50% of the cases are genetic. Autosomal recessive nonsyndromic hearing loss (ARNSHL) is one of the most common types of hereditary hearing loss. Here, a novel MYO15A missense mutation was identified in a Chinese family with ARNSHL, using targeted genetic sequencing and Sanger sequencing. Case presentation: A 6-year-old girl with congenital nonsyndromic sensorineural deafness was presented from the First Affiliated hospital of Chongqing Medical University, China. We used targeted region sequencing, Sanger sequencing, functional prediction, and three-dimensional protein structure modeling to identify and verify the genes responsible for deafness in the family. Conclusions We found pathogenic compound heterozygous mutations in MYO15A, including a novel missense mutation, c.6353T > C (p.Leu2118Pro). It could provide help not only for genetic counseling but also for further understanding of the functional role of MYO15A mutations.

scholarly journals Four Novel Variants in POU4F3 Cause Autosomal Dominant Nonsyndromic Hearing Loss

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Tian-Yi Cui ◽  
Xue Gao ◽  
Sha-Sha Huang ◽  
Yan-Yan Sun ◽  
Si-Qi Zhang ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Autosomal Dominant ◽  
Asian Population ◽  
Nonsyndromic Hearing Loss ◽  
Hereditary Hearing Loss ◽  
Variant Of Uncertain Significance ◽  
Targeted Next Generation Sequencing ◽  
Pathogenic Variants ◽  
Novel Variants ◽  
Uncertain Significance

Hereditary hearing loss is one of the most common sensory disabilities worldwide. Mutation of POU domain class 4 transcription factor 3 (POU4F3) is considered the pathogenic cause of autosomal dominant nonsyndromic hearing loss (ADNSHL), designated as autosomal dominant nonsyndromic deafness 15. In this study, four novel variants in POU4F3, c.696G>T (p.Glu232Asp), c.325C>T (p.His109Tyr), c.635T>C (p.Leu212Pro), and c.183delG (p.Ala62Argfs∗22), were identified in four different Chinese families with ADNSHL by targeted next-generation sequencing and Sanger sequencing. Based on the American College of Medical Genetics and Genomics guidelines, c.183delG (p.Ala62Argfs∗22) is classified as a pathogenic variant, c.696G>T (p.Glu232Asp) and c.635T>C (p.Leu212Pro) are classified as likely pathogenic variants, and c.325C>T (p.His109Tyr) is classified as a variant of uncertain significance. Based on previous reports and the results of this study, we speculated that POU4F3 pathogenic variants are significant contributors to ADNSHL in the East Asian population. Therefore, screening of POU4F3 should be a routine examination for the diagnosis of hereditary hearing loss.

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