1
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Zehri Z, Khan H, Ahmed S, Khan MJ, Shahwani NA, Nawaz S, Umair M. Delineating the Disease Boundaries: Homozygous CDC14A Variants Underlying Nonsyndromic Hearing Loss and Hearing Impairment Infertile Male Syndrome. Mol Syndromol 2024; 15:269-274. [PMID: 39119445 PMCID: PMC11305659 DOI: 10.1159/000536016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 12/26/2023] [Indexed: 08/10/2024] Open
Abstract
Background Hereditary hearing loss is a genetically heterogeneous neurosensory disorder that affects many people. Deafness and infertility can coexist in some cases, creating the hearing impairment infertile male syndrome. There are several known molecular mechanisms that can cause deafness either on its own or in conjunction with infertility. Methods and Results Here, we represent two consanguineous families (A, B), both families had clinical evidence of deafness, and family B also had infertility, so we referred to them as having nonsyndromic hearing loss (NSHL) and hearing impairment infertile male syndrome (HIIMS), respectively. These families' genetic makeup was examined using an Affymetrix GeneChip 250K Nsp array followed by Sanger sequencing. In family A, we identified a novel homozygous stop gain variant [NM_003672.4; c.1000C>T; p.(Gln334*)] and a homozygous missense variant [NM_003672.4; c.684C>A; p.(Asn228Lys)] in family B in CDC14A gene (MIM#603504). In animal models, the CDC14A gene causes both hearing loss and infertility; in addition, it also causes NSHL and HIIMS in humans. Conclusions Our study on the CDC14A gene has identified two novel variants, crucial for delineating disease boundaries. Variants in exon 10 and upstream cause HIIMS, and those in exon 11 and downstream are linked exclusively to hearing impairment. This precision enhances diagnostics and offers potential for targeted interventions, marking a significant advancement in understanding the genetic basis of these conditions.
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Affiliation(s)
- Zamrud Zehri
- Department of Gynecology and Obstetrics, Civil Hospital Quetta, Quetta, Pakistan
| | - Hammal Khan
- Department of Biosciences, COMSATS University Islamabad, Islamabad, Pakistan
| | - Sohail Ahmed
- Institute of Biochemistry, University of Balochistan, Quetta, Pakistan
| | | | - Nisar Ahmed Shahwani
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Balochistan, Quetta, Pakistan
| | - Shoaib Nawaz
- Department of Human Genetics, Sidra Medicine, Doha, Qatar
| | - Muhammad Umair
- Department of Life Sciences, School of Science, University of Management and Technology (UMT), Lahore, Pakistan
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2
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Gu P, Wang G, Gao X, Kang D, Dai P, Huang S. Clinical and molecular findings in a Chinese family with a de novo mitochondrial A1555G mutation. BMC Med Genomics 2022; 15:121. [PMID: 35614445 PMCID: PMC9131558 DOI: 10.1186/s12920-022-01276-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 05/17/2022] [Indexed: 11/10/2022] Open
Abstract
Background The mitochondrial 12S rRNA A1555G mutation is the most prevalent deafness-causing mitochondrial DNA (mtDNA) mutation and is inherited maternally. Studies have suggested that A1555G mutations have multiple origins, although there is no direct evidence of this. Here, we identified a family with a de novo A1555G mutation. Method Based on detailed mtDNA analyses of the family members using next-generation sequencing with 1% sensitivity to mutated mtDNA, the level of heteroplasmy in terms of the A1555G mutation in blood DNA samples was quantified. Results An individual harbored a heterogeneous A1555G mutation, at 28.68% heteroplasmy. The individual’s son was also a heterogeneous carrier, with 7.25% heteroplasmy. The individual’s brother and mother did not carry the A1555G mutation, and both had less than 1% mitochondrial 12S rRNA A1555G heteroplasmy. Conclusion The A1555G mutation arose de novo in this family. This is the first report of a family with a de novo A1555G mutation, providing direct evidence of its multipoint origin. This is important for both diagnostic investigations and genetic counselling.
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Affiliation(s)
- Ping Gu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Do.28 Fuxing Road, Beijing, 100853, People's Republic of China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, People's Republic of China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, People's Republic of China.,Department of Otolaryngology, Shenzhen Children's Hospital, Shenzhen, 518038, People's Republic of China
| | - Guojian Wang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Do.28 Fuxing Road, Beijing, 100853, People's Republic of China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, People's Republic of China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, People's Republic of China
| | - Xue Gao
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Do.28 Fuxing Road, Beijing, 100853, People's Republic of China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, People's Republic of China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, People's Republic of China
| | - Dongyang Kang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Do.28 Fuxing Road, Beijing, 100853, People's Republic of China.,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, People's Republic of China.,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, People's Republic of China
| | - Pu Dai
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Do.28 Fuxing Road, Beijing, 100853, People's Republic of China. .,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, People's Republic of China. .,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, People's Republic of China.
| | - Shasha Huang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, Do.28 Fuxing Road, Beijing, 100853, People's Republic of China. .,National Clinical Research Center for Otolaryngologic Diseases, State Key Lab of Hearing Science, Ministry of Education, Beijing, People's Republic of China. .,Beijing Key Lab of Hearing Impairment Prevention and Treatment, Beijing, People's Republic of China.
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3
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Božanić Urbančič N, Battelino S, Tesovnik T, Trebušak Podkrajšek K. The Importance of Early Genetic Diagnostics of Hearing Loss in Children. MEDICINA (KAUNAS, LITHUANIA) 2020; 56:E471. [PMID: 32937936 PMCID: PMC7558651 DOI: 10.3390/medicina56090471] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/30/2020] [Accepted: 09/10/2020] [Indexed: 11/28/2022]
Abstract
Hearing loss is one of the most common sensory deficits. It carries severe medical and social consequences, and therefore, universal newborn hearing screening was introduced at the beginning of this century. Affected patients can have hearing loss as a solitary deficit (non-syndromic hearing loss) or have other organs affected as well (syndromic hearing loss). In around 60% of cases, congenital hearing loss has a genetic etiology, where disease-causing variants can change any component of the hearing pathway. Genetic testing is usually performed by sequencing. Sanger sequencing enables analysis of the limited number of genes strictly preselected according to the clinical presentation and the prevalence among the hearing loss patients. In contrast, next-generation sequencing allows broad analysis of the numerous genes related to hearing loss, exome, or the whole genome. Identification of the genetic etiology is possible, and it makes the foundation for the genetic counselling in the family. Furthermore, it enables the identification of the comorbidities that may need a referral for specialty care, allows early treatment, helps with identification of candidates for cochlear implant, appropriate aversive/protective management, and is the foundation for the development of novel therapeutic options.
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Affiliation(s)
- Nina Božanić Urbančič
- Department of Otorhinolaryngology and Cervicofacial Surgery, University Medical Centre Ljubljana, Zaloska 2, 1000 Ljubljana, Slovenia;
- Department of Otorhinolaryngology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Saba Battelino
- Department of Otorhinolaryngology and Cervicofacial Surgery, University Medical Centre Ljubljana, Zaloska 2, 1000 Ljubljana, Slovenia;
- Department of Otorhinolaryngology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Tine Tesovnik
- University Children’s Hospital, University Medical Centre Ljubljana, Bohoriceva 20, 1000 Ljubljana, Slovenia; (T.T.); (K.T.P.)
| | - Katarina Trebušak Podkrajšek
- University Children’s Hospital, University Medical Centre Ljubljana, Bohoriceva 20, 1000 Ljubljana, Slovenia; (T.T.); (K.T.P.)
- Faculty of Medicine, Institute of Biochemistry, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
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4
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Jimenez JE, Nourbakhsh A, Colbert B, Mittal R, Yan D, Green CL, Nisenbaum E, Liu G, Bencie N, Rudman J, Blanton SH, Zhong Liu X. Diagnostic and therapeutic applications of genomic medicine in progressive, late-onset, nonsyndromic sensorineural hearing loss. Gene 2020; 747:144677. [PMID: 32304785 PMCID: PMC7244213 DOI: 10.1016/j.gene.2020.144677] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/12/2020] [Accepted: 04/14/2020] [Indexed: 02/06/2023]
Abstract
The progressive, late-onset, nonsyndromic, sensorineural hearing loss (PNSHL) is the most common cause of sensory impairment globally, with presbycusis affecting greater than a third of individuals over the age of 65. The etiology underlying PNSHL include presbycusis, noise-induced hearing loss, drug ototoxicity, and delayed-onset autosomal dominant hearing loss (AD PNSHL). The objective of this article is to discuss the potential diagnostic and therapeutic applications of genomic medicine in PNSHL. Genomic factors contribute greatly to PNSHL. The heritability of presbycusis ranges from 25 to 75%. Current therapies for PNSHL range from sound amplification to cochlear implantation (CI). PNSHL is an excellent candidate for genomic medicine approaches as it is common, has well-described pathophysiology, has a wide time window for treatment, and is amenable to local gene therapy by currently utilized procedural approaches. AD PNSHL is especially suited to genomic medicine approaches that can disrupt the expression of an aberrant protein product. Gene therapy is emerging as a potential therapeutic strategy for the treatment of PNSHL. Viral gene delivery approaches have demonstrated promising results in human clinical trials for two inherited causes of blindness and are being used for PNSHL in animal models and a human trial. Non-viral gene therapy approaches are useful in situations where a transient biologic effect is needed or for delivery of genome editing reagents (such as CRISPR/Cas9) into the inner ear. Many gene therapy modalities that have proven efficacious in animal trials have potential to delay or prevent PNSHL in humans. The development of new treatment modalities for PNSHL will lead to improved quality of life of many affected individuals and their families.
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Affiliation(s)
- Joaquin E Jimenez
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Aida Nourbakhsh
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Brett Colbert
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Human Genetics and John P. Hussman Institute of Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA; Medical Scientist Training Program, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Carlos L Green
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Eric Nisenbaum
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - George Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Nicole Bencie
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jason Rudman
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Susan H Blanton
- Department of Human Genetics and John P. Hussman Institute of Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, USA; Department of Human Genetics and John P. Hussman Institute of Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA.
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5
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Kaheel H, Breß A, Hassan MA, Shah AA, Amin M, Bakhit YHY, Kniper M. Frequency of mitochondrial m.1555A > G mutation in Syrian patients with non-syndromic hearing impairment. BMC EAR, NOSE, AND THROAT DISORDERS 2018; 18:7. [PMID: 29942192 PMCID: PMC5963064 DOI: 10.1186/s12901-018-0055-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 05/08/2018] [Indexed: 11/21/2022]
Abstract
Background Mitochondrial maternally inherited hearing impairment (HI) appears to be increasing in frequency. The incidence of mitochondrial defects causing HI is estimated to be between 6 and 33% of all hearing deficiencies. Mitochondrial m.1555A > G mutation is the first mtDNA mutation associated with non-syndromic sensorineural deafness and also with aminoglycoside induced HI. Its prevalence varied geographically between different populations. Methods We carried out PCR, restriction enzyme based screening, and sequencing of 337 subjects (including 132 patients diagnosed clinically with hereditary deafness) from 54 families from Syria for m.1555A > G mitochondrial mutation. Results Mitochondrial m.1555A > G mutation was detected in one of fifty-four families (1.85%), six out of the 132 (4.5%) of all patients with NSHI and one propositus of the 205 individuals with normal hearing (0.48%). Conclusion This is the first study to report prelingual deafness causative gene mutations identified by sequencing technology in Syrian families. It is obvious from the results that the testing for the m.1555A > G mutation is useful for diagnosis of hearing loss in Syrian patients and should also be considered prior to treatment with aminoglycosides in predisposed individuals.
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Affiliation(s)
- Hazem Kaheel
- University, HNO -universities Klink-Tubingen, Tubingen, Germany
| | - Andreas Breß
- University, HNO -universities Klink-Tubingen, Tubingen, Germany
| | - Mohamed A Hassan
- University, HNO -universities Klink-Tubingen, Tubingen, Germany.,Department of Bioinformatics, Africa city of technology, Khartoum, Sudan.,Division of Molecular Genetics, Institute of Human Genetics, University of Tübingen, Tübingen, Germany, African city of Technology, Khartoum, Sudan
| | - Aftab Ali Shah
- 3Faculty of Biotechnology, University of Malakand, Khyber Pakhtunkhwa, Pakistan
| | - Mutaz Amin
- 4Department of Biochemistry, Faculty of Medicine, University of Khartoum, P. O. Box 102, Khartoum, Sudan
| | - Yousuf H Y Bakhit
- 5Department of Basic Medical Sciences, Faculty of Dentistry-University of Khartoum, Khartoum, Sudan
| | - Marlies Kniper
- University, HNO -universities Klink-Tubingen, Tubingen, Germany
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6
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Luo J, Bai X, Zhang F, Xiao Y, Gu L, Han Y, Fan Z, Li J, Xu L, Wang H. Prevalence of Mutations in Deafness-Causing Genes in Cochlear Implanted Patients with Profound Nonsyndromic Sensorineural Hearing Loss in Shandong Province, China. Ann Hum Genet 2017; 81:258-266. [PMID: 28786104 DOI: 10.1111/ahg.12207] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 11/27/2022]
Abstract
The mutations of GJB2, SLC26A4, and mtDNA12SrRNA are the most common inherited causes of nonsyndromic sensorineural hearing loss (NSHL) in China, yet previous genetic screenings were mainly carried on patients with moderate-to-profound impairment. We aimed to detect the mutation frequencies in NSHL population within a more specified range of severity. Patients with profound NSHL who had undergone cochlear implantation in the Shandong Provincial Hospital (Shandong, China) were recruited. The majority (n = 472) were between 0.7 and 6 years old, and the remaining (n = 63) were between 6 and 70 years old. In total, 115 mutation alleles of the three genes were screened with SNP scan assay. Of the patients, 19.44% (104/535) were found to have GJB2 mutations, and the most common allele was c.235delC, followed by c.299_300delAT and c.109G>A. SLC26A4 mutations were detected in 13.46% patients (72/535), and the most common allele was c.919-2A>G (IVS7-2A>G), followed by c.1174A>T and c.2168A>G. Seven patients (1.31%) carried mutations in mtDNA12SrRNA, with the alleles of m.1555A>G and m.1494C>T. We found the allele frequency of c.109G>A (GJB2) was relatively lower in the profound NSHL population in comparison to the moderate-to-profound ones, and the c.1174A>T (SLC26A4) relatively higher. It suggests those mutations may be connected with the degree of deafness, which needs more observations and analyses to support.
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Affiliation(s)
- Jianfen Luo
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Xiaohui Bai
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Fengguo Zhang
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Yun Xiao
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Lintao Gu
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China
| | - Yuechen Han
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Zhaomin Fan
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Jianfeng Li
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Lei Xu
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
| | - Haibo Wang
- Department of Otorhinolaryngology Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China.,Shandong Provincial Key Laboratory of Otology, Shandong, China
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7
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Han R, Li L, Duan L, Xia Y, Kuyaxi P, Zhao J, Zhao Q, Zhang H, Chen Y. Efficiency of microarray and SNPscan for the detection of hearing loss gene in 71 cases with nonsyndromic hearing loss. Medicine (Baltimore) 2017. [PMID: 28640090 PMCID: PMC5484198 DOI: 10.1097/md.0000000000007149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
We aim to screen the mutations of 3 hearing loss (HL) genes (GJB2, SLC26A4, and 12S rRNA) in 71 cases with nonsyndromic hearing loss (NSHL) using microarray and SNPscan, and identify the roles of nonhotspot mutation of these genes in the screening of NSHL. Seventy-one cases with moderate or severe neurosensory deafness confirmed in our department from July 2014 to December 2015 including 25 Uyghur minorities and 46 Han Chinese were included in this study. The type of mutations in GJB2, SLC26A4, and 12S rRNA genes were detected using microarray and SNPscan, respectively. Statistical difference was noticed in the detection rate of the HL genes in 71 cases. Using microassay, deafness genes were identified in 10 subjects (14.08%), while 22 cases (30.98%) were confirmed with the presence of deafness genes using the SNPscan. Compared with the microarray, remarkable difference was noticed in the detection rate of SNPscan (P < .05). Nonhotspot mutation in GJB2, SLC26A4, and 12S rRNA genes played a crucial role in the pathogenesis of NSHL. SNPscan contributed to elevation of detection rate of NSHL in clinical practice.
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Affiliation(s)
| | - Linge Li
- Department of Otolaryngology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | | | | | - Pilidong Kuyaxi
- Department of Otolaryngology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Juan Zhao
- Department of Otolaryngology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Qi Zhao
- Department of Otolaryngology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Hua Zhang
- Department of Otolaryngology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Yu Chen
- Department of Otolaryngology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
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8
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Subathra M, Ramesh A, Selvakumari M, Karthikeyen NP, Srisailapathy CRS. Genetic Epidemiology of Mitochondrial Pathogenic Variants Causing Nonsyndromic Hearing Loss in a Large Cohort of South Indian Hearing Impaired Individuals. Ann Hum Genet 2017; 80:257-73. [PMID: 27530448 DOI: 10.1111/ahg.12161] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 05/16/2016] [Indexed: 01/28/2023]
Abstract
Mitochondria play a critical role in the generation of metabolic energy in the form of ATP. Tissues and organs that are highly dependent on aerobic metabolism are involved in mitochondrial disorders including nonsyndromic hearing loss (NSHL). Seven pathogenic variants leading to NSHL have so far been reported on two mitochondrial genes: MT-RNR1 encoding 12SrRNA and MT-TS1 encoding tRNA for Ser((UCN)) . We screened 729 prelingual NSHL subjects to determine the prevalence of MT-RNR1 variants at position m.961, m.1555A>G and m.1494C>T, and MT-TS1 m.7445A>G, m.7472insC m.7510T>C and m.7511T>C variants. Mitochondrial pathogenic variants were found in eight probands (1.1%). Five of them were found to have the m.1555A>G variant, two others had m.7472insC and one proband had m.7444G>A. The extended relatives of these probands showed variable degrees of hearing loss and age at onset. This study shows that mitochondrial pathogenic alleles contribute to about 1% prelingual hearing loss. This study will henceforth provide the reference for the prevalence of mitochondrial pathogenic alleles in the South Indian population, which to date has not been estimated. The m.1555A>G variant is a primary predisposing genetic factor for the development of hearing loss. Our study strongly suggests that mitochondrial genotyping should be considered for all hearing impaired individuals and particularly in families where transmission is compatible with maternal inheritance, after ruling out the most common variants.
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Affiliation(s)
- Mahalingam Subathra
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
| | - Arabandi Ramesh
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
| | - Mathiyalagan Selvakumari
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
| | - N P Karthikeyen
- DOAST (Doctrine Oriented Art of Symbiotic Treatment) Hearing Care Center and Integrated Therapy Center for Autism, Anna Nagar West, Chennai, India
| | - C R Srikumari Srisailapathy
- Department of Genetics, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
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9
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Application of SNPscan in Genetic Screening for Common Hearing Loss Genes. PLoS One 2016; 11:e0165650. [PMID: 27792752 PMCID: PMC5085070 DOI: 10.1371/journal.pone.0165650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 10/14/2016] [Indexed: 11/19/2022] Open
Abstract
The current study reports the successful application of a fast and efficient genetic screening system for common hearing loss (HL) genes based on SNPscan genotyping technology. Genetic analysis of 115 variants in common genes related to HL, GJB2, SLC26A4 and MT-RNR, was performed on 695 subjects with non-syndromic hearing loss (NSHL) from the Northern China. The results found that 38.7% (269/695) of cases carried bi-allelic pathogenic variants in GJB2 and SLC26A4 and 0.7% (5/695) of cases carried homoplasmic MT-RNR1 variants. The variant allele frequency of GJB2, SLC26A4 and MT-RNR1 was 19.8% (275/1390), 21.9% (304/1390), and 0.86% (6/695), respectively. This approach can explain ~40% of NSHL cases and thus is a useful tool for establishing primary molecular diagnosis of NSHL in clinical genetics.
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10
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Audiological manifestations in mitochondrial encephalomyopathy lactic acidosis and stroke like episodes (MELAS) syndrome. Clin Neurol Neurosurg 2016; 148:17-21. [DOI: 10.1016/j.clineuro.2016.04.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 07/10/2015] [Accepted: 04/26/2016] [Indexed: 11/23/2022]
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11
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12
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Comparative study of mutation spectrums of MT-RNR1 m.1555A>G, GJB2, and SLC26A4 between familial and sporadic patients with nonsyndromic sensorineural hearing loss in Chinese Han. Chin Med J (Engl) 2014. [DOI: 10.1097/00029330-201409200-00008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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13
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Al-Malky G, Suri R, Sirimanna T, Dawson SJ. Normal hearing in a child with the m.1555A>G mutation despite repeated exposure to aminoglycosides. Has the penetrance of this pharmacogenetic interaction been overestimated? Int J Pediatr Otorhinolaryngol 2014; 78:969-73. [PMID: 24703164 DOI: 10.1016/j.ijporl.2014.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 01/02/2014] [Accepted: 02/07/2014] [Indexed: 11/24/2022]
Abstract
The mtDNA m.1555A>G mutation causes increased susceptibility to aminoglycoside ototoxicity resulting in significant hearing loss in 100% of reported exposed cases. Genetic and audiological assessments were conducted in a sample of 59 children with cystic fibrosis (CF) undergoing aminoglycoside treatment. Of the two m.1555G patients identified one had severe-profound deafness. Surprisingly, the second m.1555G patient exhibited well-preserved hearing despite repeated exposure. This may be a rare case of intact hearing in an m.1555G individual with aminoglycoside use. Alternatively, its penetrance may have been previously overestimated due to recruitment bias. Further studies are required to determine the true penetrance to inform m.1555A>G genetic testing in similar clinical scenarios.
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Affiliation(s)
| | - Ranjan Suri
- Department of Paediatric Respiratory Medicine, Great Ormond Street Hospital and the Portex Unit, Institute of Child Health, UCL, London, UK
| | - Tony Sirimanna
- Department of Audiology & Audiological Medicine, Great Ormond Street Hospital, London, UK
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Vivero RJ, Ouyang X, Kim YG, Liu W, Du L, Yan D, Liu XZ. Audiologic and genetic features of the A3243G mtDNA mutation. Genet Test Mol Biomarkers 2013; 17:383-9. [PMID: 23477312 DOI: 10.1089/gtmb.2012.0403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Mitochondrial mutations have been shown to be responsible for syndromic and nonsyndromic hearing impairment. AIM To assess the genotypic-phenotypic correlation of mitochondrial DNA mutations in three generations of a single family. METHODS A single family with maternally inherited diabetes and hearing loss was recruited. Genomic DNA was subject to polymerase chain reaction-restriction fragment length polymorphism analysis (ApaI) for A3243G mutation detection and confirmation with direct DNA sequencing. The degree of heteroplasmy for the A3243G mutation in blood DNA samples was quantified. In addition, we reviewed audiological data of A3243G-associated hearing loss cases from the literature to provide details of audiologic features. RESULTS Six of 11 family members were recruited. All affected members harbored the A3243G mutation. Four of six members had diabetes. Five of five affected members demonstrated hearing loss ranging from mild to severe. The degree of heteroplasmy ranged from 5.51% to 27.74%. CONCLUSIONS Patients with a greater percentage of heteroplasmy have a trend toward more severe phenotypic presentations. Hearing loss is bilateral, sensorineural, and symmetric. The main audiogram shapes found were sloping. Additional studies are necessary to clarify the relationship between degree of heteroplasmy and phenotypic presentation.
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Affiliation(s)
- Richard J Vivero
- Department of Otolaryngology, University of Miami Ear Institute, Miami, Florida 33136, USA
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ANGELI SIMON, LIN XI, LIU XUEZHONG. Genetics of hearing and deafness. Anat Rec (Hoboken) 2012; 295:1812-29. [PMID: 23044516 PMCID: PMC4523052 DOI: 10.1002/ar.22579] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 01/20/2023]
Abstract
This article is a review of the genes and genetic disorders that affect hearing in humans and a few selected mouse models of deafness. Genetics is playing an increasingly critical role in the practice of medicine. This is not only in part to the importance that genetic knowledge has on traditional genetic diseases but also in part to the fact that genetic knowledge provides an understanding of the fundamental biological process of most diseases. The proteins coded by the genes related to hearing loss (HL) are involved in many functions in the ear, such as cochlear fluid homeostasis, ionic channels, stereocilia morphology and function, synaptic transmission, gene regulation, and others. Mouse models play a crucial role in understanding of the pathogenesis associated with these genes. Different types of familial HL have been recognized for years; however, in the last two decades, there has been tremendous progress in the discovery of gene mutations that cause deafness. Most of the cases of genetic deafness recognized today are monogenic disorders that can be broadly classified by the mode of inheritance (i.e., autosomal dominant, autosomal recessive, X-linked, and mitochondrial inheritance) and by the presence of associated phenotypic features (i.e., syndromic; and nonsyndromic). In terms of nonsyndromic HL, the chromosomal locations are currently known for ∼ 125 loci (54 for dominant and 71 for recessive deafness), 64 genes have been identified (24 for dominant and 40 for recessive deafness), and there are many more loci for syndromic deafness and X-linked and mitochondrial DNA disorders (http://hereditaryhearingloss.org). Thus, today's clinician must understand the science of medical genetics as this knowledge can lead to more effective disease diagnosis, counseling, treatment, and prevention.
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Affiliation(s)
- SIMON ANGELI
- Department of Otolaryngology, University of Miami, Miami, Florida
| | - XI LIN
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, Georgia
| | - XUE ZHONG LIU
- Department of Otolaryngology, University of Miami, Miami, Florida
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Cabanillas Farpón R, Cadiñanos Bañales J. Hereditary Hearing Loss: Genetic Counselling. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2012. [DOI: 10.1016/j.otoeng.2011.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Chen G, He F, Fu S, Dong J. GJB2 and mitochondrial DNA 1555A>G mutations in students with hearing loss in the Hubei Province of China. Int J Pediatr Otorhinolaryngol 2011; 75:1156-9. [PMID: 21777984 DOI: 10.1016/j.ijporl.2011.06.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 06/12/2011] [Accepted: 06/16/2011] [Indexed: 10/17/2022]
Abstract
OBJECTIVES The GJB2 and MTRNR1 1555A>G mutations are the prevalent causes of hearing loss worldwide. However, the mutation profiles of the two genes are dependent on the ethnic or geographic origins. Therefore, this study was to characterize the forms and frequencies of the two genes in 813 students with hearing loss in Hubei province, Central China. METHODS Blood samples from 813 students were obtained with informed consent. Genomic DNA was extracted from peripheral blood leukocytes. The target fragments were amplified by polymerase chain reaction (PCR). Sequencing (or enzyme digestion) was applied to identify sequence variations. RESULTS Ten different mutations were identified in GJB2 in 146 of the 813 (17.96%) patients and 11.81% (96/813) patients had homoplasmic mtDNA 1555A>G mutation. CONCLUSIONS This study demonstrated the high prevalence of GJB2 and mtDNA 1555A>G mutations in Central Chinese population. Therefore, it will be effective to perform GJB2 and mtDNA 1555A>G mutation analysis for genetic screening for hearing loss in this population.
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Affiliation(s)
- Guanming Chen
- Department of Otolaryngology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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[Hereditary hearing loss: genetic counselling]. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2011; 63:218-29. [PMID: 21514544 DOI: 10.1016/j.otorri.2011.02.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 02/20/2011] [Indexed: 11/22/2022]
Abstract
The aim of this review is to provide an updated overview of hereditary hearing loss, with special attention to the etiological diagnosis of sensorineural hearing loss, the genes most frequently mutated in our environment, the techniques available for their analysis and the clinical implications of genetic diagnosis. More than 60% of childhood sensorineural hearing loss is genetic. In adults, the percentage of hereditary hearing loss is unknown. Genetic testing is the highest yielding test for evaluating patients with sensorineural hearing loss. The process of genetic counselling is intended to inform patients and their families of the medical, psychological and familial implications of genetic diseases, as well as the risks, benefits and limitations of genetic testing. The implementation of any genetic analysis must be always preceded by an appropriate genetic counselling process.
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Chen G, Wang X, Fu S. Prevalence of A1555G mitochondrial mutation in Chinese newborns and the correlation with neonatal hearing screening. Int J Pediatr Otorhinolaryngol 2011; 75:532-4. [PMID: 21324532 DOI: 10.1016/j.ijporl.2011.01.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 01/04/2011] [Accepted: 01/11/2011] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To investigate the feasibility of genetic screening for deafness causative genes in the process of newborn hearing screening in China. METHODS Total 865 newborn babies between November 2009 and March 2010 were enrolled for the simultaneous hearing and deafness causative gene screening in Tongji Hospital, Wuhan, China. Hearing screening followed a two-stage strategy with transient evoked otoacoustic emissions. Infants referred after the second-stage screening were tested by diagnostic auditory brainstem response (ABR). Genomic DNA was extracted from heel blood of newborns, and the mitochondrial 12S rRNA A1555G mutation was detected by polymerase chain reaction (PCR) based restriction fragment length polymorphism and confirmed by DNA sequencing. RESULTS In hearing screening, 134 out of the 865 newborns (15.5%) were referred after the first-stage screening and 86.6% (116/134) of them returned for the second stage. After the second-stage screening, 15 who were still referred were tested by diagnostic ABR and 3 of them failed the test. On the other hand, gene screening identified 6 of the 865 newborns (0.7%) harbored homoplasmic 12S rRNA A1555G mutation although they passed the hearing screening. CONCLUSION It might be practical and effective to complement routine hearing screening in newborns with gene screening for the purpose of early diagnosis and discovery of the late-onset hearing loss.
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Affiliation(s)
- Guanming Chen
- Department of Otolaryngology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Wang QJ, Zhao YL, Rao SQ, Guo YF, He Y, Lan L, Yang WY, Zheng QY, Ruben RJ, Han DY, Shen Y. Newborn hearing concurrent gene screening can improve care for hearing loss: a study on 14,913 Chinese newborns. Int J Pediatr Otorhinolaryngol 2011; 75:535-42. [PMID: 21329993 DOI: 10.1016/j.ijporl.2011.01.016] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 01/11/2011] [Accepted: 01/11/2011] [Indexed: 10/18/2022]
Abstract
OBJECTIVE Newborn hearing screening has been widely adopted and made an achievement to some degree. Current screening protocols rely solely on detecting existing auditory disorders at the time of screening and are unable to identify individuals susceptible to auditory disorders in later life. Even if the hearing loss newborn is referred, most cases could not be diagnosed until 6-12 months old with no etiology being elucidated. This study reports the first effort to combine traditional hearing screening with genetic screening to improve the efficacy of newborn hearing screening. METHODS This study was undertaken in 12 regional hospitals located in 11 provinces of China. 14,913 newborn babies received hearing concurrent genetic screening. The hearing screening was performed with OAE or AABR. Blood sample was collected with a universal newborn genetic screening card. And three common gene, mtDNA 12S rRNA, GJB2 and SLC26A4 were screened with standard protocol. RESULTS Among all the 14,913 newborns, 86.1% (12,837/14,913) individuals passed the first-step hearing screening, 7.8% (1168/14,913) babies passed only one side, and the other 6.1% (908/14,913) were bilaterally referred. Gene screening found 306 individuals had one or two mutant alleles, the carrier rate is 2.05% (306/14,913) among the entire newborn population. The risk for hearing loss was 100% (7/7) for those newborns carrying causative GJB2 or SLC26A4 mutations (homozygotes or compound heterozygotes), 14.4% (23/160) for GJB2 heterozygote carriers, 12.3% (15/122) for SLC26A2 heterozygous carriers, and the total prevalence of referral hearing screening was approximately 14.7% (45/306). However, 85.3% (261/306) newborns passed hearing screening among these carriers including 18 newborns with 12S rRNA mt.1555A>G pathogenic mutation, who would suffer from sudden hearing loss once applying aminoglycoside drugs. CONCLUSION The cohort studies provided the essential population parameters for developing effective programs for hearing care of newborns in China. Hearing concurrent gene screening in newborns may confirm the abnormal results from hearing screening tests, help to find the etiologic of the hearing loss, and better recognize infants at risk for late-onset hearing loss occurring prior to speech and language development. In conclusion, a survey on 14,913 Chinese newborns proved that concurrent genetic screening could improve newborn hearing screening for hearing defects.
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Affiliation(s)
- Qiu-Ju Wang
- Department of Otolaryngology-Head and Neck Surgery, and Institute of Otolaryngology, Chinese People's Liberation Army General Hospital, Beijing, China.
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Ji YB, Han DY, Lan L, Wang DY, Zong L, Zhao FF, Liu Q, Benedict-Alderfer C, Zheng QY, Wang QJ. Molecular epidemiological analysis of mitochondrial DNA12SrRNA A1555G, GJB2, and SLC26A4 mutations in sporadic outpatients with nonsyndromic sensorineural hearing loss in China. Acta Otolaryngol 2011; 131:124-9. [PMID: 21162657 DOI: 10.3109/00016489.2010.483479] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION GJB2 mutation was frequent in sporadic outpatients and its mutation frequency was significant higher in the prelingual group than in the postlingual group, whereas the mutation of mtDNA A1555G and SLC26A4 was very rare in Chinese sporadic outpatients with nonsyndromic sensorineural hearing loss (NSHL). Standard and comprehensive inclusion and grouping criteria are necessary for epidemiological studies of deafness-related gene mutations. OBJECTIVES This study aimed to examine the mutations of the three common deafness genes GJB2, SLC26A4, and mtDNA A1555G in Chinese sporadic outpatients with NSHL and to discuss the factors that influence the detection accuracy of mutation frequencies. METHODS A total of 473 sporadic NSHL patients without any type of inner ear malformation, including both prelingual and postlingual groups were enrolled in this study. Three genes of mtDNA A1555G, GJB2, and SLC26A4 were screened for mutation in our study cohort. A chi-square test was performed to compare mutation frequencies between prelingual and postlingual groups. RESULTS The mutation frequencies of MtDNA A1555G, GJB2, and SLC26A4 were 1.63%, 13.63%, and 0%, respectively, in our study cohort. The mutational hot spot of GJB2 was c.235delC, whose allele frequency was 12.68% in sporadic outpatients. Mutation frequency of GJB2 in the prelingual group was significantly higher than in the postlingual group (p < 0.05).
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Affiliation(s)
- Yu-bin Ji
- Department of Otolaryngology/Head and Neck Surgery, Chinese PLA Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
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Fu S, Yan J, Wang X, Dong J, Chen P, Wang C, Chen G. The audiological characteristics of a hereditary Y-linked hearing loss in a Chinese ethnic Tujia pedigree. Int J Pediatr Otorhinolaryngol 2011; 75:202-6. [PMID: 21130505 DOI: 10.1016/j.ijporl.2010.10.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 10/29/2010] [Accepted: 10/30/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To investigate audiometric characteristics of hearing loss in a large Chinese ethnic Tujia family and determine its hereditary type. METHODS Total 76 live individuals were investigated in the notable 84 members of this family. The detailed audiometric evaluations were undertaken for the proband and his 47 family members. The degrees of sensorineural hearing impairment were defined as an air/bone gap <15dB hearing loss averaged over 0.5, 1 and 2kHz. The severity of hearing loss was established based on the hearing ability of the better ear, averaged over 0.5, 1, 2 and 4kHz, and classified into four categories: mild, moderate, severe and profound. RESULTS Nineteen patrilineal relatives of the 76 live members had hearing impairment. The age of onset ranged from 7 to 21 years old with the average of 13.2 years. The audiometric defect was described by auditory curves of a high frequency in 47% of the patients. Affected members in this family demonstrated a non-syndromic, late onset, bilateral, symmetrical, postlingual and sensorineural hearing loss. CONCLUSIONS The audiometric configuration in males of the pedigree is consistent with the hereditary Y-linked hearing loss. Thus we speculate that a putative gene on the Y chromosome could contribute to the cause of the disease.
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Affiliation(s)
- Siqing Fu
- Department of Medical Genetics, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Kokotas H, Grigoriadou M, Yang L, Lodahl M, Rendtorff ND, Gyftodimou Y, Korres GS, Ferekidou E, Kandiloros D, Korres S, Tranebjærg L, Guan MX, Petersen MB. Homoplasmy of the G7444A mtDNA and heterozygosity of the GJB2 c.35delG mutations in a family with hearing loss. Int J Pediatr Otorhinolaryngol 2011; 75:89-94. [PMID: 21056478 DOI: 10.1016/j.ijporl.2010.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 10/05/2010] [Accepted: 10/09/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE Mitochondrial mutations have been shown to be responsible for syndromic as well as non-syndromic hearing loss. The G7444A mitochondrial DNA mutation affects COI/the precursor of tRNA(Ser(UCN)), encoding the first subunit of cytochrome oxidase. Here we report on the first Greek family with the G7444A mitochondrial DNA mutation. METHODS Clinical, cytogenetic, and molecular methods were employed in this study. RESULTS We describe the high variability of phenotypes among three family members harboring the G7444A mutation and also the frequent GJB2 c.35delG mutation of the nuclear genome in heterozygosity. Their phenotypes ranged from normal hearing to deafness, while the proband presented with several other symptoms. CONCLUSIONS The G7444A mitochondrial DNA mutation has been reported in only a few cases worldwide, alone or in cosegregation with other mitochondrial DNA mutations, but to our knowledge, never before in coexistence with the GJB2 c.35delG mutation.
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Affiliation(s)
- Haris Kokotas
- Department of Genetics, Institute of Child Health, Aghia Sophia Children's Hospital, Athens, Greece.
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Guan MX. Mitochondrial 12S rRNA mutations associated with aminoglycoside ototoxicity. Mitochondrion 2010; 11:237-45. [PMID: 21047563 DOI: 10.1016/j.mito.2010.10.006] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 08/31/2010] [Accepted: 10/19/2010] [Indexed: 11/18/2022]
Abstract
The mitochondrial 12S rRNA is a hot spot for mutations associated with both aminoglycoside-induced and nonsyndromic hearing loss. Of those, the homoplasmic 1555A>G and 1494C>T mutations at the highly conserved decoding region of the 12S rRNA have been associated with hearing loss worldwide. In particular, these two mutations account for a significant number of cases of aminoglycoside ototoxicity. The 1555A>G or 1494C>T mutation is expected to form a novel 1494C-G1555 or 1494U-A1555 base-pair at the highly conserved A-site of 12S rRNA. These transitions make the human mitochondrial ribosomes more bacteria-like and alter binding sites for aminoglycosides. As a result, the exposure to aminoglycosides can induce or worsen hearing loss in individuals carrying one of these mutations. Biochemical characterization demonstrated an impairment of mitochondrial protein synthesis and subsequent defects in respiration in cells carrying the A1555G or 1494C>T mutation. Furthermore, a wide range of severity, age-at-onset and penetrance of hearing loss was observed within and among families carrying these mutations. Nuclear modifier genes, mitochondrial haplotypes and aminoglycosides should modulate the phenotypic manifestation of the 12S rRNA 1555A>G and 1494C>T mutations. Therefore, these data provide valuable information and technology: (1) to predict which individuals are at risk for ototoxicity; (2) to improve the safety of aminoglycoside antibiotic therapy; and (3) eventually to decrease the incidence of hearing loss.
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Affiliation(s)
- Min-Xin Guan
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229-3039, USA.
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Siem G, Fagerheim T, Jonsrud C, Laurent C, Teig E, Harris S, Leren TP, Früh A, Heimdal K. Causes of hearing impairment in the Norwegian paediatric cochlear implant program. Int J Audiol 2010; 49:596-605. [DOI: 10.3109/14992021003743269] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Ouyang XM, Yan D, Yuan HJ, Pu D, Du LL, Han DY, Liu XZ. The genetic bases for non-syndromic hearing loss among Chinese. J Hum Genet 2009; 54:131-40. [PMID: 19197336 DOI: 10.1038/jhg.2009.4] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Deafness is an etiologically heterogeneous trait with many known genetic, environmental causes or a combination thereof. The identification of more than 120 independent genes for deafness has provided profound new insights into the pathophysiology of hearing. However, recent findings indicate that a large proportion of both syndromic and non-syndromic forms of deafness in the Chinese population are caused by defects in a small number of genes. Studies of the genetic epidemiology and molecular genetic features revealed that there is a clear relevance of genes causing deafness in Chinese deaf patients as well as a unique spectrum of common and rare deafness gene mutations in the Chinese population. This review is focused on the genetic aspects of non-syndromic and mitochondrial deafness, in which unique molecular genetic features of hearing impairment have been identified in the Chinese population. The current China population is approximately 1.3 billion. It is estimated that 30,000 infants are born with congenital sensorineural hearing loss each year. Better understanding of the genetic causes of deafness in the Chinese population is important for accurate genetics counseling and early diagnosis for timely intervention and treatment options.
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Affiliation(s)
- Xiao Mei Ouyang
- Department of Otolaryngology, University of Miami, Miami, FL 33136, USA
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