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BODIPY-Conjugated Xyloside Primes Fluorescent Glycosaminoglycans in the Inner Ear of Opsanus tau. J Assoc Res Otolaryngol 2016; 17:525-540. [PMID: 27619213 DOI: 10.1007/s10162-016-0585-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 08/23/2016] [Indexed: 12/22/2022] Open
Abstract
We report on a new xyloside conjugated to BODIPY, BX and its utility to prime fluorescent glycosaminoglycans (BX-GAGs) within the inner ear in vivo. When BX is administered directly into the endolymphatic space of the oyster toadfish (Opsanus tau) inner ear, fluorescent BX-GAGs are primed and become visible in the sensory epithelia of the semicircular canals, utricle, and saccule. Confocal and 2-photon microscopy of vestibular organs fixed 4 h following BX treatment, reveal BX-GAGs constituting glycocalyces that envelop hair cell kinocilium, nerve fibers, and capillaries. In the presence of GAG-specific enzymes, the BX-GAG signals are diminished, suggesting that chondroitin sulfates are the primary GAGs primed by BX. Results are consistent with similar click-xylosides in CHO cell lines, where the xyloside enters the Golgi and preferentially initiates chondroitin sulfate B production. Introduction of BX produces a temporary block of hair cell mechanoelectrical transduction (MET) currents in the crista, reduction in background discharge rate of afferent neurons, and a reduction in sensitivity to physiological stimulation. A six-degree-of-freedom pharmacokinetic mathematical model has been applied to interpret the time course and spatial distribution of BX and BX-GAGs. Results demonstrate a new optical approach to study GAG biology in the inner ear, for tracking synthesis and localization in real time.
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A reverse genetic approach identifies an ancestral frameshift mutation in RP1 causing recessive progressive retinal degeneration in European cattle breeds. Genet Sel Evol 2016; 48:56. [PMID: 27510606 PMCID: PMC4980790 DOI: 10.1186/s12711-016-0232-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/26/2016] [Indexed: 01/17/2023] Open
Abstract
Background Domestication and artificial selection have resulted in strong genetic drift, relaxation of purifying selection and accumulation of deleterious mutations. As a consequence, bovine breeds experience regular outbreaks of recessive genetic defects which might represent only the tip of the iceberg since their detection depends on the observation of affected animals with distinctive symptoms. Thus, recessive mutations resulting in embryonic mortality or in non-specific symptoms are likely to be missed. The increasing availability of whole-genome sequences has opened new research avenues such as reverse genetics for their investigation. Our aim was to characterize the genetic load of 15 European breeds using data from the 1000 bull genomes consortium and prove that widespread harmful mutations remain to be detected. Results We listed 2489 putative deleterious variants (in 1923 genes) segregating at a minimal frequency of 5 % in at least one of the breeds studied. Gene enrichment analysis showed major enrichment for genes related to nervous, visual and auditory systems, and moderate enrichment for genes related to cardiovascular and musculoskeletal systems. For verification purposes, we investigated the phenotypic consequences of a frameshift variant in the retinitis pigmentosa-1 gene segregating in several breeds and at a high frequency (27 %) in Normande cattle. As described in certain human patients, clinical and histological examination revealed that this mutation causes progressive degeneration of photoreceptors leading to complete blindness in homozygotes. We established that the deleterious allele was even more frequent in the Normande breed before 1975 (>40 %) and has been progressively counter-selected likely because of its associated negative effect on udder morphology. Finally, using identity-by-descent analysis we demonstrated that this mutation resulted from a unique ancestral event that dates back to ~2800 to 4000 years. Conclusions We provide a list of mutations that likely represent a substantial part of the genetic load of domestication in European cattle. We demonstrate that they accumulated non-randomly and that genes related to cognition and sensory functions are particularly affected. Finally, we describe an ancestral deleterious variant segregating in different breeds causing progressive retinal degeneration and irreversible blindness in adult animals. Electronic supplementary material The online version of this article (doi:10.1186/s12711-016-0232-y) contains supplementary material, which is available to authorized users.
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Imtiaz A, Maqsood A, Rehman AU, Morell RJ, Holt JR, Friedman TB, Naz S. Recessive mutations of TMC1 associated with moderate to severe hearing loss. Neurogenetics 2016; 17:115-123. [PMID: 26879195 PMCID: PMC4795972 DOI: 10.1007/s10048-016-0477-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 02/09/2016] [Indexed: 12/12/2022]
Abstract
TMC1 encodes a protein required for the normal function of mechanically activated channels that enable sensory transduction in auditory and vestibular hair cells. TMC1 protein is localized at the tips of the hair cell stereocilia, the site of conventional mechanotransduction. In many populations, loss-of-function recessive mutations of TMC1 are associated with profound deafness across all frequencies tested. In six families reported here, variable moderate-to-severe or moderate-to-profound hearing loss co-segregated with STR (short tandem repeats) markers at the TMC1 locus DFNB7/11. Massively parallel and Sanger sequencing of genomic DNA revealed each family co-segregating hearing loss with a homozygous TMC1 mutation: two reported mutations (p.R34X and p.R389Q) and three novel mutations (p.S596R, p.N199I, and c.1404 + 1G > T). TMC1 cDNA sequence from affected subjects homozygous for the donor splice site transversion c.1404 + 1G > T revealed skipping of exon 16, deleting 60 amino acids from the TMC1 protein. Since the mutations in our study cause less than profound hearing loss, we speculate that there is hypo-functional TMC1 mechanotransduction channel activity and that other even less damaging variants of TMC1 may be associated with more common mild-to-severe sensorineural hearing loss.
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Affiliation(s)
- Ayesha Imtiaz
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, USA 20892
| | - Azra Maqsood
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
| | - Atteeq U. Rehman
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, USA 20892
| | - Robert J. Morell
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, USA 20892
| | - Jeffrey R. Holt
- Department of Otolaryngology, F. M. Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Thomas B. Friedman
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, USA 20892
| | - Sadaf Naz
- School of Biological Sciences, University of the Punjab, Quaid-i-Azam Campus, Lahore 54590, Pakistan
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Basch ML, Brown RM, Jen H, Groves AK. Where hearing starts: the development of the mammalian cochlea. J Anat 2016; 228:233-54. [PMID: 26052920 PMCID: PMC4718162 DOI: 10.1111/joa.12314] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2015] [Indexed: 12/11/2022] Open
Abstract
The mammalian cochlea is a remarkable sensory organ, capable of perceiving sound over a range of 10(12) in pressure, and discriminating both infrasonic and ultrasonic frequencies in different species. The sensory hair cells of the mammalian cochlea are exquisitely sensitive, responding to atomic-level deflections at speeds on the order of tens of microseconds. The number and placement of hair cells are precisely determined during inner ear development, and a large number of developmental processes sculpt the shape, size and morphology of these cells along the length of the cochlear duct to make them optimally responsive to different sound frequencies. In this review, we briefly discuss the evolutionary origins of the mammalian cochlea, and then describe the successive developmental processes that lead to its induction, cell cycle exit, cellular patterning and the establishment of topologically distinct frequency responses along its length.
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Affiliation(s)
- Martin L. Basch
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
| | - Rogers M. Brown
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Hsin‐I Jen
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
| | - Andrew K. Groves
- Department of NeuroscienceBaylor College of MedicineHoustonTXUSA
- Program in Developmental BiologyBaylor College of MedicineHoustonTXUSA
- Department of Molecular and Human GeneticsBaylor College of MedicineHoustonTXUSA
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Yao Q, DeSmidt AA, Tekin M, Liu X, Lu Z. Hearing Assessment in Zebrafish During the First Week Postfertilization. Zebrafish 2016; 13:79-86. [PMID: 26982161 DOI: 10.1089/zeb.2015.1166] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The zebrafish (Danio rerio) is a valuable vertebrate model for human hearing disorders because of many advantages in genetics, embryology, and in vivo visualization. In this study, we investigated auditory function of zebrafish during the first week postfertilization using microphonic potential recording. Extracellular microphonic potentials were recorded from hair cells in the inner ear of wild-type AB and transgenic Et(krt4:GFP)(sqet4) zebrafish at 3, 5, and 7 days postfertilization in response to 20, 50, 100, 200, 300, and 400-Hz acoustic stimulation. We found that microphonic threshold significantly decreased with age in zebrafish. However, there was no significant difference of microphonic responses between wild-type and transgenic zebrafish, indicating that the transgenic zebrafish have normal hearing like wild-type zebrafish. In addition, we observed that microphonic threshold did not change with the recording electrode location. Furthermore, microphonic threshold increased significantly at all tested stimulus frequencies after displacement of the saccular otolith but only increased at low frequencies after displacement of the utricular otolith, showing that the saccule rather than the utricle plays the major role in larval zebrafish hearing. These results enhance our knowledge of early development of auditory function in zebrafish and the factors affecting hearing assessment with microphonic potential recording.
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Affiliation(s)
- Qi Yao
- 1 Department of Biology, University of Miami , Coral Gables, Florida
- 2 Department of Otolaryngology, University of Miami Miller School of Medicine , Miami, Florida
| | | | - Mustafa Tekin
- 2 Department of Otolaryngology, University of Miami Miller School of Medicine , Miami, Florida
- 3 Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine , Miami, Florida
| | - Xuezhong Liu
- 2 Department of Otolaryngology, University of Miami Miller School of Medicine , Miami, Florida
- 3 Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine , Miami, Florida
- 4 Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China
| | - Zhongmin Lu
- 1 Department of Biology, University of Miami , Coral Gables, Florida
- 5 Neuroscience Program, University of Miami , Miami, Florida
- 6 International Center for Marine Studies, Shanghai Ocean University , Shanghai, People's Republic of China
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El Hakam Kamareddin C, Magnol L, Blanquet V. A new Otogelin ENU mouse model for autosomal-recessive nonsyndromic moderate hearing impairment. SPRINGERPLUS 2015; 4:730. [PMID: 26636018 PMCID: PMC4659790 DOI: 10.1186/s40064-015-1537-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 11/13/2015] [Indexed: 02/03/2023]
Abstract
Approximately 10 % of the population worldwide suffers from hearing loss (HL) and about 60 % of persons with early onset HL have hereditary hearing loss due to genetic mutations. Highly efficient mutagenesis in mice with the chemical mutagen, ethylnitrosourea (ENU), associated with relevant phenotypic tools represents a powerful approach in producing mouse models for hearing impairment. A benefit of this strategy is to generate alleles to form a series revealing the full spectrum of gene function in vivo. It can also mimic the range of human mutations and polymorphisms for HL. In the course of a genome ENU mutagenesis program, we selected a new mouse model for hearing defect based on a dysmorphological screen. We identified by gene mapping the mutation responsible for this phenotype and characterized it at the histological level of the inner ear and evaluated the vestibule by following the recommendations of the standard operating procedures, IMPReSS. We have identified and characterized a new recessive allele of the otogelin gene, Otogvbd/vbd, due to a homozygous one base pair substitution at the splice donor site of intron 29. This mutation leads to a frame-shift and a premature stop codon. We observed a decrease in the amount of sensory cells in the maculae of Otogvbd/vbd mice as well as an apparent drastically decreased density to almost absence of the otoconial membrane. Compared to Otogtm1Prs and twister, the two other existing otogelin alleles, the detailed analysis of Otogvbd/vbd revealed that these mice share some common behavioural characteristics either with Otogtm1Prs or twister whereas the fine vestibular phenotype and the hearing defect are different. Our results emphasize the importance of detecting and characterizing a new allele of a gene in order to get comprehensive information about the gene function.
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Affiliation(s)
- Carole El Hakam Kamareddin
- Univ. Limoges, INRA, UMR 1061, Unité de Génétique Moléculaire Animale, Faculté des Sciences et Techniques, 123, Avenue Albert Thomas, 87060 Limoges, France
| | - Laetitia Magnol
- Univ. Limoges, INRA, UMR 1061, Unité de Génétique Moléculaire Animale, Faculté des Sciences et Techniques, 123, Avenue Albert Thomas, 87060 Limoges, France
| | - Veronique Blanquet
- Univ. Limoges, INRA, UMR 1061, Unité de Génétique Moléculaire Animale, Faculté des Sciences et Techniques, 123, Avenue Albert Thomas, 87060 Limoges, France
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The Genetic Architecture of Hearing Impairment in Mice: Evidence for Frequency-Specific Genetic Determinants. G3-GENES GENOMES GENETICS 2015; 5:2329-39. [PMID: 26342000 PMCID: PMC4632053 DOI: 10.1534/g3.115.021592] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Genome-wide association studies (GWAS) have been successfully applied in humans for the study of many complex phenotypes. However, identification of the genetic determinants of hearing in adults has been hampered, in part, by the relative inability to control for environmental factors that might affect hearing throughout the lifetime, as well as a large degree of phenotypic heterogeneity. These and other factors have limited the number of large-scale studies performed in humans that have identified candidate genes that contribute to the etiology of this complex trait. To address these limitations, we performed a GWAS analysis using a set of inbred mouse strains from the Hybrid Mouse Diversity Panel. Among 99 strains characterized, we observed approximately two-fold to five-fold variation in hearing at six different frequencies, which are differentiated biologically from each other by the location in the cochlea where each frequency is registered. Among all frequencies tested, we identified a total of nine significant loci, several of which contained promising candidate genes for follow-up study. Taken together, our results indicate the existence of both genes that affect global cochlear function, as well as anatomical- and frequency-specific genes, and further demonstrate the complex nature of mammalian hearing variation.
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Hofrichter MAH, Nanda I, Gräf J, Schröder J, Shehata-Dieler W, Vona B, Haaf T. A Novel de novo Mutation in CEACAM16 Associated with Postlingual Hearing Impairment. Mol Syndromol 2015; 6:156-63. [PMID: 26648831 DOI: 10.1159/000439576] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2015] [Indexed: 12/20/2022] Open
Abstract
Mutations in CEACAM16 cause autosomal dominant nonsyndromic hearing loss (DFNA4B). So far, 2 families have been reported with segregating missense mutations, both in the immunoglobulin constant domain A of the CEACAM16 protein. In this study, we used the TruSight One panel to investigate a parent-child trio without familial history of hearing loss and one affected child. When filtering for recessive inheritance and de novo events, we discovered a de novo CEACAM16 mutation (c.1094T>G, p.Leu365Arg) as the sole likely pathogenic variant. The de novo mutation was confirmed by Sanger sequencing and STR analysis. The proband's hearing loss closely matches the described onset and severity for DFNA4B. We present the third CEACAM16 variant and the first de novo mutation in CEACAM16. This de novo mutation is robustly described as a pathogenic mutation according to in silico mutation prediction tools and affects a highly conserved amino acid in the most strongly conserved CEACAM16 N2 domain. Our strategy of screening family trios enhances de novo mutation discovery and the exclusion of other variants of potential interest through pedigree filtering.
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Affiliation(s)
| | - Indrajit Nanda
- Department of Human Genetics, Julius Maximilian University, Würzburg, Germany
| | - Jens Gräf
- Department of Human Genetics, Julius Maximilian University, Würzburg, Germany
| | - Jörg Schröder
- Department of Human Genetics, Julius Maximilian University, Würzburg, Germany
| | - Wafaa Shehata-Dieler
- Department of Otorhinolaryngology, Comprehensive Hearing Center, University Hospitals, Würzburg, Germany
| | - Barbara Vona
- Department of Human Genetics, Julius Maximilian University, Würzburg, Germany
| | - Thomas Haaf
- Department of Human Genetics, Julius Maximilian University, Würzburg, Germany
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Bademci G, Foster J, Mahdieh N, Bonyadi M, Duman D, Cengiz FB, Menendez I, Diaz-Horta O, Shirkavand A, Zeinali S, Subasioglu A, Tokgoz-Yilmaz S, Huesca-Hernandez F, de la Luz Arenas-Sordo M, Dominguez-Aburto J, Hernandez-Zamora E, Montenegro P, Paredes R, Moreta G, Vinueza R, Villegas F, Mendoza-Benitez S, Guo S, Bozan N, Tos T, Incesulu A, Sennaroglu G, Blanton SH, Ozturkmen-Akay H, Yildirim-Baylan M, Tekin M. Comprehensive analysis via exome sequencing uncovers genetic etiology in autosomal recessive nonsyndromic deafness in a large multiethnic cohort. Genet Med 2015. [PMID: 26226137 PMCID: PMC4733433 DOI: 10.1038/gim.2015.89] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Purpose Autosomal recessive non-syndromic deafness (ARNSD) is characterized by a high degree of genetic heterogeneity with reported mutations in 58 different genes. This study was designed to detect deafness causing variants in a multiethnic cohort with ARNSD by using whole-exome sequencing (WES). Methods After excluding mutations in the most common gene, GJB2, we performed WES in 160 multiplex families with ARNSD from Turkey, Iran, Mexico, Ecuador and Puerto Rico to screen for mutations in all known ARNSD genes. Results We detected ARNSD-causing variants in 90 (56%) families, 54% of which had not been previously reported. Identified mutations were located in 31 known ARNSD genes. The most common genes with mutations were MYO15A (13%), MYO7A (11%), SLC26A4 (10%), TMPRSS3 (9%), TMC1 (8%), ILDR1 (6%) and CDH23 (4%). Nine mutations were detected in multiple families with shared haplotypes suggesting founder effects. Conclusion We report on a large multiethnic cohort with ARNSD in which comprehensive analysis of all known ARNSD genes identifies causative DNA variants in 56% of the families. In the remaining families, WES allows us to search for causative variants in novel genes, thus improving our ability to explain the underlying etiology in more families.
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Affiliation(s)
- Guney Bademci
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Joseph Foster
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Nejat Mahdieh
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mortaza Bonyadi
- Faculty of Natural Sciences, Center of Excellence for Biodiversity, University of Tabriz, Tabriz, Iran
| | - Duygu Duman
- Division of Genetics, Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey
| | - F Basak Cengiz
- Division of Genetics, Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey
| | - Ibis Menendez
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Oscar Diaz-Horta
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | | | - Sirous Zeinali
- Kawsar's Human Genetic Research Center, Tehran, Iran.,Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Asli Subasioglu
- Department of Medical Genetics, Izmir Katip Celebi University, Ataturk Training and Research Hospital, Izmir, Turkey
| | - Suna Tokgoz-Yilmaz
- Department of Audiology, Hacettepe University Health Sciences Faculty, Ankara, Turkey
| | | | | | | | | | | | | | | | | | | | | | - Shengru Guo
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Nazim Bozan
- Department of Otolaryngology, Faculty of Medicine, Yuzuncu Yıl University, Van, Turkey
| | - Tulay Tos
- Department of Medical Genetics, Dr. Sami Ulus Research and Training Hospital of Women's and Children's Health and Diseases, Ankara, Turkey
| | - Armagan Incesulu
- Department of Otolaryngology, Head and Neck Surgery, Eskisehir Osmangazi University, Eskisehir, Turkey
| | - Gonca Sennaroglu
- Department of Audiology, Hacettepe University Health Sciences Faculty, Ankara, Turkey
| | - Susan H Blanton
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Hatice Ozturkmen-Akay
- Department of Radiology, Istanbul Zeynep Kamil Maternity and Children Training and Research Hospital, Istanbul, Turkey
| | | | - Mustafa Tekin
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, Florida, USA
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Gu X, Sun S, Guo L, Lu X, Mei H, Lai C, Li H. Novel biallelic OTOGL mutations in a Chinese family with moderate non-syndromic sensorineural hearing loss. Int J Pediatr Otorhinolaryngol 2015; 79:817-820. [PMID: 25829320 DOI: 10.1016/j.ijporl.2015.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 03/09/2015] [Accepted: 03/10/2015] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Autosomal recessive non-syndromic hearing loss (DFNB) is a genetically heterogeneous disorder. So far, 55 pathogenic genes have been identified. In this study, we aim to characterize the clinical feature and the genetic cause of a Chinese DFNB family. METHODS Whole exome sequencing was performed on the proband. Co-segregation between the hearing loss phenotype and the potential causative mutations was verified in all family members by Sanger sequencing. RESULTS Audiologic profiles of the affected family members revealed a moderate hearing loss mainly affecting higher frequencies. Novel biallelic OTOGL mutations, c.6467C>A (p.Ser2156*) and c.6474dupA (p.Ser2159Metfs*2), were identified in this family segregating with the childhood onset DFNB. Both mutations were predicted to cause either nonsense mediated mRNA decay or premature terminations of protein synthesis. CONCLUSIONS We identified novel biallelic OTOGL mutations in a Chinese DFNB family. To the best of our knowledge, this is the first report of OTOGL mutations causing hearing loss in the East Asian population. Our finding enriched the mutation spectrum of OTOGL associated hearing loss.
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Affiliation(s)
- Xiaodong Gu
- Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Shan Sun
- Research Center, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Luo Guo
- Research Center, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Xiaoling Lu
- Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Honglin Mei
- Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Chuijin Lai
- Research Center, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Huawei Li
- Department of Otorhinolaryngology, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China; Institute of Stem Cell and Regeneration Medicine, Institutions of Biomedical Science, Fudan University, Shanghai 200032, China; State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China; Key Laboratory of Hearing Science, Ministry of Health, Affiliated Eye and ENT Hospital of Fudan University, Shanghai 200031, China.
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Stooke-Vaughan GA, Obholzer ND, Baxendale S, Megason SG, Whitfield TT. Otolith tethering in the zebrafish otic vesicle requires Otogelin and α-Tectorin. Development 2015; 142:1137-45. [PMID: 25758224 PMCID: PMC4360185 DOI: 10.1242/dev.116632] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Otoliths are biomineralised structures important for balance and hearing in fish. Their counterparts in the mammalian inner ear, otoconia, have a primarily vestibular function. Otoliths and otoconia form over sensory maculae and are attached to the otolithic membrane, a gelatinous extracellular matrix that provides a physical coupling between the otolith and the underlying sensory epithelium. In this study, we have identified two proteins required for otolith tethering in the zebrafish ear, and propose that there are at least two stages to this process: seeding and maintenance. The initial seeding step, in which otolith precursor particles tether directly to the tips of hair cell kinocilia, fails to occur in the einstein (eis) mutant. The gene disrupted in eis is otogelin (otog); mutations in the human OTOG gene have recently been identified as causative for deafness and vestibular dysfunction (DFNB18B). At later larval stages, maintenance of otolith tethering to the saccular macula is dependent on tectorin alpha (tecta) function, which is disrupted in the rolling stones (rst) mutant. α-Tectorin (Tecta) is a major constituent of the tectorial membrane in the mammalian cochlea. Mutations in the human TECTA gene can cause either dominant (DFNA8/12) or recessive (DFNB21) forms of deafness. Our findings indicate that the composition of extracellular otic membranes is highly conserved between mammals and fish, reinforcing the view that the zebrafish is an excellent model system for the study of deafness and vestibular disease.
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Affiliation(s)
| | - Nikolaus D Obholzer
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Sarah Baxendale
- Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
| | - Sean G Megason
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Tanya T Whitfield
- Bateson Centre and Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
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Vona B, Nanda I, Hofrichter MAH, Shehata-Dieler W, Haaf T. Non-syndromic hearing loss gene identification: A brief history and glimpse into the future. Mol Cell Probes 2015; 29:260-70. [PMID: 25845345 DOI: 10.1016/j.mcp.2015.03.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/19/2015] [Accepted: 03/23/2015] [Indexed: 11/27/2022]
Abstract
From the first identified non-syndromic hearing loss gene in 1995, to those discovered in present day, the field of human genetics has witnessed an unparalleled revolution that includes the completion of the Human Genome Project in 2003 to the $1000 genome in 2014. This review highlights the classical and cutting-edge strategies for non-syndromic hearing loss gene identification that have been used throughout the twenty year history with a special emphasis on how the innovative breakthroughs in next generation sequencing technology have forever changed candidate gene approaches. The simplified approach afforded by next generation sequencing technology provides a second chance for the many linked loci in large and well characterized families that have been identified by linkage analysis but have presently failed to identify a causative gene. It also discusses some complexities that may restrict eventual candidate gene discovery and calls for novel approaches to answer some of the questions that make this simple Mendelian disorder so intriguing.
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Affiliation(s)
- Barbara Vona
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany.
| | - Indrajit Nanda
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
| | | | - Wafaa Shehata-Dieler
- Comprehensive Hearing Center, Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Surgery, University Hospital, Würzburg, Germany
| | - Thomas Haaf
- Institute of Human Genetics, Julius Maximilians University, Würzburg, Germany
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63
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Abstract
Next-generation sequencing (NGS) technologies have played a central role in the genetic revolution. These technologies, especially whole-exome sequencing, have become the primary tool of geneticists to identify the causative DNA variants in Mendelian disorders, including hereditary deafness. Current research estimates that 1% of all human genes have a function in hearing. To date, mutations in over 80 genes have been reported to cause nonsyndromic hearing loss (NSHL). Strikingly, more than a quarter of all known genes related to NSHL were discovered in the past 5 years via NGS technologies. In this article, we review recent developments in the usage of NGS for hereditary deafness, with an emphasis on whole-exome sequencing.
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64
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Nishio SY, Hattori M, Moteki H, Tsukada K, Miyagawa M, Naito T, Yoshimura H, Iwasa YI, Mori K, Shima Y, Sakuma N, Usami SI. Gene expression profiles of the cochlea and vestibular endorgans: localization and function of genes causing deafness. Ann Otol Rhinol Laryngol 2015; 124 Suppl 1:6S-48S. [PMID: 25814645 DOI: 10.1177/0003489415575549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. METHODS Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Homepage using localization, expression, and distribution as keywords. RESULTS Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. CONCLUSIONS The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.
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Affiliation(s)
- Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Mitsuru Hattori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Maiko Miyagawa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Takehiko Naito
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hidekane Yoshimura
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yoh-Ichiro Iwasa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Kentaro Mori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yutaka Shima
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Naoko Sakuma
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Otorhinolaryngology and Head and Neck Surgery, Yokohama City University School of Medicine, Yokohama, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
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Abstract
Hearing loss is the most common form of sensory impairment in humans and affects more than 40 million people in the United States alone. No drug-based therapy has been approved by the Food and Drug Administration, and treatment mostly relies on devices such as hearing aids and cochlear implants. Over recent years, more than 100 genetic loci have been linked to hearing loss and many of the affected genes have been identified. This understanding of the genetic pathways that regulate auditory function has revealed new targets for pharmacological treatment of the disease. Moreover, approaches that are based on stem cells and gene therapy, which may have the potential to restore or maintain auditory function, are beginning to emerge.
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Affiliation(s)
- Ulrich Müller
- Department of Molecular and Cellular Neuroscience, Dorris Neuroscience Center, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, San Diego, California 92037, USA
| | - Peter G Barr-Gillespie
- Oregon Hearing Research Center, Vollum Institute, Oregon Health &Science University, 3181 South West Sam Jackson Park Road, Portland, Oregon 97239, USA
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66
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Whole-exome sequencing reveals diverse modes of inheritance in sporadic mild to moderate sensorineural hearing loss in a pediatric population. Genet Med 2015; 17:901-11. [PMID: 25719458 DOI: 10.1038/gim.2014.213] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 12/22/2014] [Indexed: 11/09/2022] Open
Abstract
PURPOSE This study was designed to delineate genetic contributions, if any, to sporadic forms of mild to moderate sensorineural hearing loss (SNHL) not related to GJB2 mutations (DFNB1) in a pediatric population. METHODS We recruited 11 non-DFNB1 simplex cases of mild to moderate SNHL in children. We applied whole-exome sequencing to all 11 probands. We used a filtering strategy assuming that de novo variants of known autosomal dominant (AD) deafness genes, biallelic mutations in autosomal recessive (AR) genes, monoallelic mutations in X chromosome genes for males, and digenic inheritance could be associated. Candidate variants first were prioritized with allele frequency in public databases and confirmed by a phase or a segregation test in each family. Additional information from the literature or public databases was used to identify strong candidate variants. RESULTS Strong candidate variants were detected in 5 of 11 probands (45.4%). A diverse mode of inheritance implicated the sporadic occurrence of the phenotype. AR mutations in OTOGL and SERPINB6 and digenic inheritance involving two deafness genes, GPR98 and PDZ7, were detected. A de novo AD mutation also was detected in TECTA and MYH14. No syndromic feature was detected in individuals with GPR98/PDZ7 or MYH14 variants in our cohort at this moment. CONCLUSION Mild to moderate pediatric SNHL, even if sporadic, features a strong genetic etiology and can manifest via diverse modes of inheritance. In addition, a multidisciplinary approach should be used for a correct diagnosis.
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67
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Downsloping high-frequency hearing loss due to inner ear tricellular tight junction disruption by a novel ILDR1 mutation in the Ig-like domain. PLoS One 2015; 10:e0116931. [PMID: 25668204 PMCID: PMC4323246 DOI: 10.1371/journal.pone.0116931] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 12/16/2014] [Indexed: 11/19/2022] Open
Abstract
The immunoglobulin (Ig)-like domain containing receptor 1 (ILDR1) gene encodes angulin-2/ILDR1, a recently discovered tight junction protein, which forms tricellular tight junction (tTJ) structures with tricellulin and lipolysis-stimulated lipoprotein receptor (LSR) at tricellular contacts (TCs) in the inner ear. Previously reported recessive mutations within ILDR1 have been shown to cause severe to profound nonsyndromic sensorineural hearing loss (SNHL), DFNB42. Whole-exome sequencing of a Korean multiplex family segregating partial deafness identified a novel homozygous ILDR1 variant (p.P69H) within the Ig-like domain. To address the pathogenicity of p.P69H, the angulin-2/ILDR1 p.P69H variant protein, along with the previously reported pathogenic ILDR1 mutations, was expressed in angulin-1/LSR knockdown epithelial cells. Interestingly, partial mislocalization of the p.P69H variant protein and tricellulin at TCs was observed, in contrast to a severe mislocalization and complete failure of tricellulin recruitment of the other reported ILDR1 mutations. Additionally, three-dimensional protein modeling revealed that angulin-2/ILDR1 contributed to tTJ by forming a homo-trimer structure through its Ig-like domain, and the p.P69H variant was predicted to disturb homo-trimer formation. In this study, we propose a possible role of angulin-2/ILDR1 in tTJ formation in the inner ear and a wider audiologic phenotypic spectrum of DFNB42 caused by mutations within ILDR1.
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68
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Abstract
OBJECTIVES Recently, OTOG and OTOGL were identified as human deafness genes. Currently, only four families are known to have autosomal recessive hearing loss based on mutations in these genes. Because the two genes code for proteins (otogelin and otogelin-like) that are strikingly similar in structure and localization in the inner ear, this study is focused on characterizing and comparing the hearing loss caused by mutations in these genes. DESIGN To evaluate this type of hearing, an extensive set of audiometric and vestibular examinations was performed in the 13 patients from four families. RESULTS All families show a flat to downsloping configuration of the audiogram with mild to moderate sensorineural hearing loss. Speech recognition scores remain good (>90%). Hearing loss is not significantly different in the four families and the psychophysical test results also do not differ among the families. Vestibular examinations show evidence for vestibular hyporeflexia. CONCLUSION Because otogelin and otogelin-like are localized in the tectorial membrane, one could expect a cochlear conductive hearing loss, as was previously shown in DFNA13 (COL11A2) and DFNA8/12 (TECTA) patients. Results of psychophysical examinations, however, do not support this. Furthermore, the authors conclude that there are no phenotypic differences between hearing loss based on mutations in OTOG or OTOGL. This phenotype description will facilitate counseling of hearing loss caused by defects in either of these two genes.
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69
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Ordóñez J, Diaz-Horta O, Tekin M. Personalized Medicine for Hereditary Deafness. Rare Dis 2015. [DOI: 10.1007/978-94-017-9214-1_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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70
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Park JH, Kim NKD, Kim AR, Rhee J, Oh SH, Koo JW, Nam JY, Park WY, Choi BY. Exploration of molecular genetic etiology for Korean cochlear implantees with severe to profound hearing loss and its implication. Orphanet J Rare Dis 2014; 9:167. [PMID: 25373420 PMCID: PMC4243193 DOI: 10.1186/s13023-014-0167-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 10/17/2014] [Indexed: 02/01/2023] Open
Abstract
Background Severe to profound sensorineural hearing loss (SNHL) requires cochlear implantation (CI) for auditory rehabilitation. Etiologic diagnoses can contribute to candidacy selection and decision-making regarding the timing of successful CI. However, few studies have been performed to address the etiologic spectrum of severe SNHL in the population where there is no consanguineous marriage and the majority of SNHL cases are sporadic in small sized families. The authors sought to comprehensively understand the etiologies of Korean cochlear implantees by incorporating the targeted resequencing of 204 candidate deafness genes (TRS-204) and a phenotype-driven candidate gene approach. Methods Ninety-three that consented to molecular genetic testing and underwent at least one molecular genetic test were included. Patients with a characteristic Phenotypic marker were subject to Sanger sequencing to detect variants in corresponding candidate genes. The rest of patients without any prominent phenotype were tested on GJB2. Next, TRS-204 was applied in GJB2-negative cases without any phenotypic marker. In addition, the sibling recurrence-risk of SNHL among families with non-diagnostic genotypes after TRS-204 was performed to gain insight of etiologies in non-diagnostic cases. Results Overall, we could find causative variants in 51 (54.8%) of the 93 cochlear implantees. Thirty (32.3%) probands could be diagnosed by direct Sanger sequencing of candidate genes selected by their phenotypes. GJB2 sequencing added 10 subjects to the group with a diagnostic genotype. TRS-204 could detect a causative variant from additional 11 cases (11.8%). We could not detect any pathogenic deletion or duplication on 204 target genes. The sibling recurrence-risk of SNHL among 42 genetically undiagnosed families with 0.03 (1/38) was significantly lower than among genetically diagnosed recessive families with 0.19 (7/37). Conclusion Despite that the majority of severe or more degree of SNHL occurs sporadically in Koreans, at least 54.8% of such cases that were willing to join the genetic study in the Korean population are monogenic Mendelian disorders with convincing causative variants. This study also indicates that a substantial portion of unsolved cases after applying our current protocol are predicted to have non-genetic or complex etiology rather than a Mendelian genetic disorder involving new genes beyond the 204 target genes. Electronic supplementary material The online version of this article (doi:10.1186/s13023-014-0167-8) contains supplementary material, which is available to authorized users.
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71
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Lundberg YW, Xu Y, Thiessen KD, Kramer KL. Mechanisms of otoconia and otolith development. Dev Dyn 2014; 244:239-53. [PMID: 25255879 DOI: 10.1002/dvdy.24195] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. RESULTS To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. CONCLUSIONS This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.
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Affiliation(s)
- Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska
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72
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Loss of the tectorial membrane protein CEACAM16 enhances spontaneous, stimulus-frequency, and transiently evoked otoacoustic emissions. J Neurosci 2014; 34:10325-38. [PMID: 25080593 DOI: 10.1523/jneurosci.1256-14.2014] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
α-Tectorin (TECTA), β-tectorin (TECTB), and carcinoembryonic antigen-related cell adhesion molecule 16 (CEACAM) are secreted glycoproteins that are present in the tectorial membrane (TM), an extracellular structure overlying the hearing organ of the inner ear, the organ of Corti. Previous studies have shown that TECTA and TECTB are both required for formation of the striated-sheet matrix within which collagen fibrils of the TM are imbedded and that CEACAM16 interacts with TECTA. To learn more about the structural and functional significance of CEACAM16, we created a Ceacam16-null mutant mouse. In the absence of CEACAM16, TECTB levels are reduced, a clearly defined striated-sheet matrix does not develop, and Hensen's stripe, a prominent feature in the basal two-thirds of the TM in WT mice, is absent. CEACAM16 is also shown to interact with TECTB, indicating that it may stabilize interactions between TECTA and TECTB. Although brain-stem evoked responses and distortion product otoacoustic emissions are, for most frequencies, normal in young mice lacking CEACAM16, stimulus-frequency and transiently evoked emissions are larger. We also observed spontaneous otoacoustic emissions (SOAEs) in 70% of the homozygous mice. This incidence is remarkable considering that <3% of WT controls have SOAEs. The predominance of SOAEs >15 kHz correlates with the loss of Hensen's stripe. Results from mice lacking CEACAM16 are consistent with the idea that the organ of Corti evolved to maximize the gain of the cochlear amplifier while preventing large oscillations. Changes in TM structure appear to influence the balance between energy generation and dissipation such that the system becomes unstable.
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73
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Lundberg YW, Xu Y, Thiessen KD, Kramer KL. Mechanisms of otoconia and otolith development. Dev Dyn 2014. [PMID: 25255879 DOI: 10.1002/dvdy.24195(2014)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Otoconia are bio-crystals that couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. RESULTS To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. CONCLUSIONS This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.
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Affiliation(s)
- Yunxia Wang Lundberg
- Vestibular Genetics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska
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74
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Genetics of auditory mechano-electrical transduction. Pflugers Arch 2014; 467:49-72. [PMID: 24957570 PMCID: PMC4281357 DOI: 10.1007/s00424-014-1552-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/04/2014] [Accepted: 06/05/2014] [Indexed: 12/29/2022]
Abstract
The hair bundles of cochlear hair cells play a central role in the auditory mechano-electrical transduction (MET) process. The identification of MET components and of associated molecular complexes by biochemical approaches is impeded by the very small number of hair cells within the cochlea. In contrast, human and mouse genetics have proven to be particularly powerful. The study of inherited forms of deafness led to the discovery of several essential proteins of the MET machinery, which are currently used as entry points to decipher the associated molecular networks. Notably, MET relies not only on the MET machinery but also on several elements ensuring the proper sound-induced oscillation of the hair bundle or the ionic environment necessary to drive the MET current. Here, we review the most significant advances in the molecular bases of the MET process that emerged from the genetics of hearing.
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75
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Choi BY, Kim J, Chung J, Kim AR, Mun SJ, Kang SI, Lee SH, Kim N, Oh SH. Whole-exome sequencing identifies a novel genotype-phenotype correlation in the entactin domain of the known deafness gene TECTA. PLoS One 2014; 9:e97040. [PMID: 24816743 PMCID: PMC4016231 DOI: 10.1371/journal.pone.0097040] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 04/14/2014] [Indexed: 12/18/2022] Open
Abstract
Postlingual progressive hearing loss, affecting primarily the high frequencies, is the clinical finding in most cases of autosomal dominant nonsyndromic hearing loss (ADNSHL). The molecular genetic etiology of ADNSHL is extremely heterogeneous. We applied whole-exome sequencing to reveal the genetic etiology of high-frequency hearing loss in a mid-sized Korean family without any prior linkage data. Whole-exome sequencing of four family members (two affected and two unaffected), together with our filtering strategy based on comprehensive bioinformatics analyses, identified 21 potential pathogenic candidates. Sanger validation of an additional five family members excluded 20 variants, leaving only one novel variant, TECTA c.710C>T (p.T237I), as the strongest candidate. This variant resides in the entactin (ENT) domain and co-segregated perfectly with non-progressive high-frequency hearing loss in the family. It was absent among 700 ethnically matched control chromosomes, and the T237 residue is conserved among species, which supports its pathogenicity. Interestingly, this finding contrasted with a previously proposed genotype-phenotype correlation in which variants of the ENT domain of TECTA were associated with mid-frequency hearing loss. Based upon what we observed, we propose a novel “genotype to phenotype” correlation in the ENT domain of TECTA. Our results shed light on another important application of whole-exome sequencing: the establishment of a novel genotype-phenotype in the molecular genetic diagnosis of autosomal dominant hearing loss.
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Affiliation(s)
- Byung Yoon Choi
- Department of Otorhinolaryngology, Seoul National University Bundang Hospital, Seongnam, South Korea
| | - Jiwoong Kim
- Korean Bioinformation center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
| | - Juyong Chung
- Department of Otolaryngology, Ajou University School of Medicine, Suwon, South Korea
| | - Ah Reum Kim
- Department of Otorhinolaryngology, Seoul national University College of Medicine, Seoul, South Korea
| | - Sue Jean Mun
- Department of Otorhinolaryngology, Seoul national University College of Medicine, Seoul, South Korea
| | - Seong Il Kang
- Department of Otorhinolaryngology, Seoul national University College of Medicine, Seoul, South Korea
| | - Sang-Heon Lee
- Korean Bioinformation center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
- Department of Bioinformatics, University of Science and Technology, Daejeon, South Korea
| | - Namshin Kim
- Korean Bioinformation center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, South Korea
- Department of Bioinformatics, University of Science and Technology, Daejeon, South Korea
- * E-mail: (NSK); (SHO)
| | - Seung-Ha Oh
- Department of Otorhinolaryngology, Seoul national University College of Medicine, Seoul, South Korea
- * E-mail: (NSK); (SHO)
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76
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Imtiaz A, Kohrman DC, Naz S. A frameshift mutation in GRXCR2 causes recessively inherited hearing loss. Hum Mutat 2014; 35:618-24. [PMID: 24619944 DOI: 10.1002/humu.22545] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2014] [Accepted: 03/04/2014] [Indexed: 01/06/2023]
Abstract
More than 360 million humans are affected with some degree of hearing loss, either early or later in life. A genetic cause for the disorder is present in a majority of the cases. We mapped a locus (DFNB101) for hearing loss in humans to chromosome 5q in a consanguineous Pakistani family. Exome sequencing revealed an insertion mutation in GRXCR2 as the cause of moderate-to-severe and likely progressive hearing loss in the affected individuals of the family. The frameshift mutation is predicted to affect a conserved, cysteine-rich region of GRXCR2, and to result in an abnormal extension of the C-terminus. Functional studies by cell transfections demonstrated that the mutant protein is unstable and mislocalized relative to wild-type GRXCR2, consistent with a loss-of-function mutation. Targeted disruption of Grxcr2 is concurrently reported to cause hearing loss in mice. The structural abnormalities in this animal model suggest a role for GRXCR2 in the development of stereocilia bundles, specialized structures on the apical surface of sensory cells in the cochlea that are critical for sound detection. Our results indicate that GRXCR2 should be considered in differential genetic diagnosis for individuals with early onset, moderate-to-severe and progressive hearing loss.
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Affiliation(s)
- Ayesha Imtiaz
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
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77
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Hoefsloot LH, Feenstra I, Kunst HPM, Kremer H. Genotype phenotype correlations for hearing impairment: approaches to management. Clin Genet 2014; 85:514-23. [PMID: 24547994 DOI: 10.1111/cge.12339] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 12/29/2013] [Accepted: 12/29/2013] [Indexed: 12/31/2022]
Abstract
Hearing impairment is an extremely heterogeneous disorder, with both environmental as well as genetic causes. This review describes the known genes involved in non-syndromic hearing impairment and their genotype-phenotype correlations where possible. Furthermore, some of the more frequent syndromic forms of hearing impairment are described, in particular where they overlap with the non-syndromic forms. Given the heterogeneity of the disorder, together with the indistinguishable phenotypes for many of the genes, it is suggested that testing for mutations is performed using massive parallel sequencing techniques, either by a large targeted set of genes or by an exome wide analysis.
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Affiliation(s)
- L H Hoefsloot
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands; Institute for Genetic and Metabolic Disease, Radboud University Medical Center, Nijmegen, the Netherlands
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Fontanesi L, Schiavo G, Galimberti G, Calò DG, Russo V. A genomewide association study for average daily gain in Italian Large White pigs. J Anim Sci 2014; 92:1385-94. [PMID: 24663154 DOI: 10.2527/jas.2013-7059] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Average daily gain is an important target trait in pig breeding programs. In this study we performed a genomewide association study for ADG in Italian Large White pigs using a selective genotyping approach. Two extreme and divergent groups of Italian Large White pigs (number 190 + 190) were selected among a population of about 10,000 performance tested gilts (EBV for ADG in the 2 groups were -30 ± 14 g and 81 ± 12 g, respectively) and genotyped with the Illumina PorcineSNP60 BeadChip. Association analysis was performed treating the pigs of the 2 extreme groups as cases and controls after correction for family-based stratification. A total of 127 SNP resulted significantly associated with ADG (P nominal value [P(raw)] < 2.0 × 10(-7), P < 0.01 Bonferroni corrected [P(Bonferroni)] < 0.01, false discovery rate < 7.76 × 10(-5)). Another 102 SNP were suggestively associated with the target trait (P(raw) between 2.0 × 10(-7) and 2.02 × 10(-6), P(Bonferroni) < 0.10, false discovery rate < 4.19 × 10(-4)). These SNP were located on all autosomes and on porcine chromosome (SSC) X. The largest number of SNP within this list was on SSC5 (n = 42), SSC7 (34), SSC6 (30), SSC4 (23), and SSC16 (16). These chromosomes were richer in significant or suggestively significant markers than expected (P < 0.001). A quite high number of these SNP (n = 23) were associated with backfat thickness in a previous genomewide association study performed in the same pig population, confirming the negative correlation between the 2 traits. Two or more SNP targeted the same gene: IGSF3 and HS2ST1 (SSC4), OTOGL (SSC5), FTO region (SSC6), and MYLK4 and MCUR1 (SSC7). Other regions that were associated with ADG in previous candidate gene studies (e.g., MC4R on SSC1, IGF2 and LDHA on SSC2, MUC4 on SSC13) 1) included markers with P(raw) < 0.01 that, however, did not pass the stringent threshold of significance adopted in this study or 2) could not be tested because not assigned to the Sscrofa10.2 genome version. Functional annotation of the significant regions using Gene Ontology suggested that many and complex processes at different levels are involved in affecting ADG, indicating the complexity of the genetic factors controlling this ultimate phenotype. The obtained results may contribute to understand the genetic mechanisms determining ADG that could open new perspectives to improve selection efficiency in this breed.
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Affiliation(s)
- L Fontanesi
- Department of Agricultural and Food Sciences, Division of Animal Sciences, University of Bologna, Viale Fanin 46, 40127 Bologna, Italy
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79
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Legan PK, Goodyear RJ, Morín M, Mencia A, Pollard H, Olavarrieta L, Korchagina J, Modamio-Hoybjor S, Mayo F, Moreno F, Moreno-Pelayo MA, Richardson GP. Three deaf mice: mouse models for TECTA-based human hereditary deafness reveal domain-specific structural phenotypes in the tectorial membrane. Hum Mol Genet 2013; 23:2551-68. [PMID: 24363064 PMCID: PMC3990158 DOI: 10.1093/hmg/ddt646] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Tecta is a modular, non-collagenous protein of the tectorial membrane (TM), an extracellular matrix of the cochlea essential for normal hearing. Missense mutations in Tecta cause dominant forms of non-syndromic deafness and a genotype-phenotype correlation has been reported in humans, with mutations in different Tecta domains causing mid- or high-frequency hearing impairments that are either stable or progressive. Three mutant mice were created as models for human Tecta mutations; the Tecta(L1820F,G1824D/+) mouse for zona pellucida (ZP) domain mutations causing stable mid-frequency hearing loss in a Belgian family, the Tecta(C1837G/+) mouse for a ZP-domain mutation underlying progressive mid-frequency hearing loss in a Spanish family and the Tecta(C1619S/+) mouse for a zonadhesin-like (ZA) domain mutation responsible for progressive, high-frequency hearing loss in a French family. Mutations in the ZP and ZA domains generate distinctly different changes in the structure of the TM. Auditory brainstem response thresholds in the 8-40 kHz range are elevated by 30-40 dB in the ZP-domain mutants, whilst those in the ZA-domain mutant are elevated by 20-30 dB. The phenotypes are stable and no evidence has been found for a progressive deterioration in TM structure or auditory function. Despite elevated auditory thresholds, the Tecta mutant mice all exhibit an enhanced tendency to have audiogenic seizures in response to white noise stimuli at low sound pressure levels (≤84 dB SPL), revealing a previously unrecognised consequence of Tecta mutations. These results, together with those from previous studies, establish an allelic series for Tecta unequivocally demonstrating an association between genotype and phenotype.
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Affiliation(s)
- P Kevin Legan
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
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80
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Novel candidate genes for 46,XY gonadal dysgenesis identified by a customized 1 M array-CGH platform. Eur J Med Genet 2013; 56:661-8. [DOI: 10.1016/j.ejmg.2013.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 09/03/2013] [Indexed: 12/14/2022]
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81
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Kim HJ, Won HH, Park KJ, Hong SH, Ki CS, Cho SS, Venselaar H, Vriend G, Kim JW. SNP linkage analysis and whole exome sequencing identify a novel POU4F3 mutation in autosomal dominant late-onset nonsyndromic hearing loss (DFNA15). PLoS One 2013; 8:e79063. [PMID: 24260153 PMCID: PMC3832514 DOI: 10.1371/journal.pone.0079063] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/24/2013] [Indexed: 11/18/2022] Open
Abstract
Autosomal dominant non-syndromic hearing loss (AD-NSHL) is one of the most common genetic diseases in human and is well-known for the considerable genetic heterogeneity. In this study, we utilized whole exome sequencing (WES) and linkage analysis for direct genetic diagnosis in AD-NSHL. The Korean family had typical AD-NSHL running over 6 generations. Linkage analysis was performed by using genome-wide single nucleotide polymorphism (SNP) chip and pinpointed a genomic region on 5q31 with a significant linkage signal. Sequential filtering of variants obtained from WES, application of the linkage region, bioinformatic analyses, and Sanger sequencing validation identified a novel missense mutation Arg326Lys (c.977G>A) in the POU homeodomain of the POU4F3 gene as the candidate disease-causing mutation in the family. POU4F3 is a known disease gene causing AD-HSLH (DFNA15) described in 5 unrelated families until now each with a unique mutation. Arg326Lys was the first missense mutation affecting the 3(rd) alpha helix of the POU homeodomain harboring a bipartite nuclear localization signal sequence. The phenotype findings in our family further supported previously noted intrafamilial and interfamilial variability of DFNA15. This study demonstrated that WES in combination with linkage analysis utilizing bi-allelic SNP markers successfully identified the disease locus and causative mutation in AD-NSHL.
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Affiliation(s)
- Hee-Jin Kim
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hong-Hee Won
- Samsung Biomedical Research Institute, Samsung Medical Center, Seoul, Korea
| | - Kyoung-Jin Park
- Samsung Biomedical Research Institute, Samsung Medical Center, Seoul, Korea
| | - Sung Hwa Hong
- Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Chang-Seok Ki
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sang Sun Cho
- Samsung Biomedical Research Institute, Samsung Medical Center, Seoul, Korea
| | - Hanka Venselaar
- Centre for Molecular and Biomolecular Informatics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Gert Vriend
- Centre for Molecular and Biomolecular Informatics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Jong-Won Kim
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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82
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Biallelic nonsense mutations in the otogelin-like gene (OTOGL) in a child affected by mild to moderate hearing impairment. Gene 2013; 527:537-40. [DOI: 10.1016/j.gene.2013.06.044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 06/06/2013] [Accepted: 06/08/2013] [Indexed: 12/17/2022]
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83
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Yan D, Tekin M, Blanton SH, Liu XZ. Next-generation sequencing in genetic hearing loss. Genet Test Mol Biomarkers 2013; 17:581-7. [PMID: 23738631 DOI: 10.1089/gtmb.2012.0464] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The advent of the $1000 genome has the potential to revolutionize the identification of genes and their mutations underlying genetic disorders. This is especially true for extremely heterogeneous Mendelian conditions such as deafness, where the mutation, and indeed the gene, may be private. The recent technological advances in target-enrichment methods and next generation sequencing offer a unique opportunity to break through the barriers of limitations imposed by gene arrays. These approaches now allow for the complete analysis of all known deafness-causing genes and will result in a new wave of discoveries of the remaining genes for Mendelian disorders. In this review, we describe commonly used genomic technologies as well as the application of these technologies to the genetic diagnosis of hearing loss (HL) and to the discovery of novel genes for syndromic and nonsyndromic HL.
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Affiliation(s)
- Denise Yan
- Department of Otolaryngology, Miller School of Medicine, University of Miami, Miami, Florida 33136, USA
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85
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Lu Z, DeSmidt AA. Early development of hearing in zebrafish. J Assoc Res Otolaryngol 2013; 14:509-21. [PMID: 23575600 DOI: 10.1007/s10162-013-0386-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 03/17/2013] [Indexed: 01/27/2023] Open
Abstract
The zebrafish (Danio rerio) has become a valuable vertebrate model for human hearing and balance disorders because it combines powerful genetics, excellent embryology, and exceptional in vivo visualization in one organism. In this study, we investigated auditory function of zebrafish at early developmental stages using the microphonic potential method. This is the first study to report ontogeny of response of hair cells in any fish during the first week post fertilization. The right ear of each zebrafish embedded in agarose was linearly stimulated with a glass probe that was driven by a calibrated piezoelectric actuator. Using beveled micropipettes filled with standard fish saline, extracellular microphonic potentials were recorded from hair cells in the inner ear of zebrafish embryos or larvae in response to 20, 50, 100, and 200-Hz stimulation. Saccular hair cells expressing green fluorescent protein of the transgenic zebrafish from 2 to 7 days post fertilization (dpf) were visualized and quantified using confocal microscopy. The otic vesicles' areas, otoliths' areas, and saccular hair cell count and density increased linearly with age and standard body length. Microphonic responses increased monotonically with stimulus intensity, stimulus frequency, and age of zebrafish. Microphonic threshold at 200 Hz gradually decreased with zebrafish age. The increases in microphonic response and sensitivity correlate with the increases in number and density of hair cells in the saccule. These results enhance our knowledge of early development of auditory function in zebrafish and provide the control data that can be used to evaluate hearing of young zebrafish morphants or mutants.
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Affiliation(s)
- Zhongmin Lu
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA.
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86
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Zamora LY, Lu Z. Alcohol-induced morphological deficits in the development of octavolateral organs of the zebrafish (Danio rerio). Zebrafish 2013; 10:52-61. [PMID: 23461415 DOI: 10.1089/zeb.2012.0830] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Prenatal alcohol exposure is known to have many profound detrimental effects on human fetal development (fetal alcohol spectrum disorders), which may manifest as lifelong disabilities. However, how alcohol affects the auditory/vestibular system is still largely unknown. This is the first study to investigate morphological effects of alcohol on the developing octavolateral system (the inner ear and lateral line) using the zebrafish, Danio rerio. Zebrafish embryos of 2 hours post fertilization (hpf) were treated in 2% alcohol for 48 hours and screened at 72 hpf for morphological defects of the inner ear and lateral line. Octavolateral organs from both alcohol-treated and control zebrafish were examined using light, confocal, and scanning electron microscopy. We observed several otolith phenotypes for alcohol-treated zebrafish including zero, one, two abnormal, two normal, and multiple otoliths. Results of this study show that alcohol treatment during early development impairs the inner ear (smaller ear, abnormal otoliths, and fewer sensory hair cells) and the lateral line (smaller neuromasts, fewer neuromasts and hair cells per neuromast, and shorter kinocilia of hair cells). Early embryonic alcohol exposure may also result in defects in hearing, balance, and hydrodynamic function of zebrafish.
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Affiliation(s)
- Lilliann Y Zamora
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA
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