51
|
Phylipsen M, Traeger-Synodinos J, van der Kraan M, van Delft P, Bakker G, Geerts M, Kanavakis E, Stamoulakatou A, Karagiorga M, Giordano PC, Harteveld CL. A novel α0-thalassemia deletion in a Greek patient with HbH disease and β-thalassemia trait. Eur J Haematol 2012; 88:356-62. [DOI: 10.1111/j.1600-0609.2012.01748.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
52
|
Rădulescu L, Mârţu C, Birkenhäger R, Cozma S, Ungureanu L, Laszig R. Prevalence of mutations located at the dfnb1 locus in a population of cochlear implanted children in eastern Romania. Int J Pediatr Otorhinolaryngol 2012; 76:90-4. [PMID: 22070872 DOI: 10.1016/j.ijporl.2011.10.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 10/05/2011] [Accepted: 10/07/2011] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Hearing loss is one of the major public health problems, with a genetic etiology in more than 60% of cases. Connexin 26 and connexin 30 mutations are the most prevalent causes of deafness. The aim of this study is to characterize and to establish the prevalence of the GJB2 and GJB6 gene mutations in a population of cochlear implanted recipients from Eastern Romania, this being the first report of this type in our country. METHODS We present a retrospective study that enrolled 45 Caucasian cochlear implanted patients with non-syndromic sensorineural severe to profound, congenital or progressive with early-onset idiopathic hearing loss. We performed sequential analysis of exon 1 and the coding exon 2 of the GJB2 gene including also the splice sites and analysis of the deletions del(GJB6-D13S1830), del(GJB6-D13S1854) and del(chr13:19,837,343-19,968,698). RESULTS The genetic analysis of the GJB2 gene identified connexin 26 mutations in 22 patients out of 45 (12 homozygous for c.35delG, 6 compound heterozygous and 4 with mutations only on one allele). We found 6 different mutations, the most prevalent being c.35delG - found on 32 alleles, followed by p.W24* - found on 2 alleles. We did not identify the deletions del(GJB6-D13S1830), del(GJB6-D13S1854) and del(chr13:19,837,343-19,968,698). CONCLUSIONS Although the most prevalent mutation was c.35delG (80% from all types of mutations), unexpectedly we identified 5 more different mutations. The presence of 6 different mutations on the GJB2 gene has implications in hearing screening programs development in our region and in genetic counseling.
Collapse
|
53
|
Phylipsen M, Chaibunruang A, Vogelaar IP, Balak JRA, Schaap RAC, Ariyurek Y, Fucharoen S, den Dunnen JT, Giordano PC, Bakker E, Harteveld CL. Fine-tiling array CGH to improve diagnostics for α- and β-thalassemia rearrangements. Hum Mutat 2011; 33:272-80. [PMID: 21922597 DOI: 10.1002/humu.21612] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 08/26/2011] [Indexed: 12/21/2022]
Abstract
Implementation of multiplex ligation-dependent probe amplification (MLPA) for thalassemia causing deletions has lead to the detection of new rearrangements. Knowledge of the exact breakpoint sequences should give more insight into the molecular mechanisms underlying these rearrangements, and would facilitate the design of gap-PCRs. We have designed a custom fine-tiling array with oligonucleotides covering the complete globin gene clusters. We hybridized 27 DNA samples containing newly identified deletions and nine positive controls. We designed specific primers to amplify relatively short fragments containing the breakpoint sequence and analyzed these by direct sequencing. Results from nine positive controls showed that array comparative genomic hybridization (aCGH) is suitable to detect small and large rearrangements. We were able to locate all breakpoints to a region of approximately 2 kb. We designed breakpoint primers for 22 cases and amplification was successful in 19 cases. For 12 of these, the exact locations of the breakpoints were determined. Seven of these deletions have not been reported before. aCGH is a valuable tool for high-resolution breakpoint characterization. The combination of MLPA and aCGH has lead to relatively cheap and easy to perform PCR assays, which might be of use for laboratories as an alternative for MLPA in populations where only a limited number of specific deletions occur with high frequency.
Collapse
Affiliation(s)
- Marion Phylipsen
- Hemoglobinopathies Laboratory, Center for Human and Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
54
|
Matos TD, Simões-Teixeira H, Caria H, Cascão R, Rosa H, O'Neill A, Dias O, Andrea ME, Kelsell DP, Fialho G. Assessing Noncoding Sequence Variants of GJB2 for Hearing Loss Association. GENETICS RESEARCH INTERNATIONAL 2011; 2011:827469. [PMID: 22567369 PMCID: PMC3335567 DOI: 10.4061/2011/827469] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 07/19/2011] [Accepted: 07/27/2011] [Indexed: 12/03/2022]
Abstract
Involvement of GJB2 noncoding regions in hearing loss (HL) has not been extensively investigated. However, three noncoding mutations, c.-259C>T, c.-23G>T, and c.-23+1G>A, were reported. Also, c.-684_-675del, of uncertain pathogenicity, was found upstream of the basal promoter. We performed a detailed analysis of GJB2 noncoding regions in Portuguese HL patients (previously screened for GJB2 coding mutations and the common GJB6 deletions) and in control subjects, by sequencing the basal promoter and flanking upstream region, exon 1, and 3'UTR. All individuals were genotyped for c.-684_-675del and 14 SNPs. Novel variants (c.-731C>T, c.-26G>T, c.*45G>A, and c.*985A>T) were found in controls. A hearing individual homozygous for c.-684_-675del was for the first time identified, supporting the nonpathogenicity of this deletion. Our data indicate linkage disequilibrium (LD) between SNPs rs55704559 (c.*168A>G) and rs5030700 (c.*931C>T) and suggest the association of c.[*168G;*931T] allele with HL. The c.*168A>G change, predicted to alter mRNA folding, might be involved in HL.
Collapse
Affiliation(s)
- T D Matos
- Centre for Biodiversity, Functional, and Integrative Genomics (BioFIG), Faculty of Science, University of Lisbon, Campus FCUL, Campo Grande, 1749-016 Lisboa, Portugal
| | | | | | | | | | | | | | | | | | | |
Collapse
|
55
|
da Silva-Costa SM, Martins FTA, Pereira T, Pomilio MCA, Marques-de-Faria AP, Sartorato EL. Searching for digenic inheritance in deaf Brazilian individuals using the multiplex ligation-dependent probe amplification technique. Genet Test Mol Biomarkers 2011; 15:849-53. [PMID: 21728791 DOI: 10.1089/gtmb.2011.0034] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in the genes coding for connexin 26 (Cx26), connexin 30 (Cx30), and connexin 31 (Cx31) are the main cause of autosomal recessive nonsyndromic sensorineural hearing loss (AR-NSNHL). The 35delG mutation is the most frequent in the majority of Caucasian populations and may account for up to 70% of all GJB2 mutations. As a large number of affected individuals (10%-40%) with GJB2 mutations carry only one mutant allele, it has been postulated that the presence of additional mutations in the GJB6 gene (Cx30) explains the deafness condition found in these patients. In the present study, we screened the c.35delG mutation in ~600 unrelated Brazilian patients, with moderate to profound AR-NSNHL. Other point mutations in the coding region of the GJB2 gene were screened by sequencing analysis as well as the IVS 1+1 G>A splice site mutation in the same gene. Digenic mutations including large deletions and duplications were investigated in the Cx26, 30, and 31 genes in monoallelic individuals for mutations in the GJB2 gene. Large deletions and duplications were assessed by multiplex ligation-dependent probe amplification. We found 46 patients with mutations in only one GJB2 allele. Different pathogenic mutations associated with c.35delG were found in 13 patients. Two patients were identified with digenic heterozygous mutations. Our findings contributed to more accurate diagnosis and more appropriate genetic counseling in 28% of patients studied (13/46).
Collapse
Affiliation(s)
- Sueli M da Silva-Costa
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz s/n, Barão Geraldo, Campinas, Brazil
| | | | | | | | | | | |
Collapse
|
56
|
Mahdieh N, Rabbani B, Shirkavand A, Bagherian H, Movahed ZS, Fouladi P, Rahiminejad F, Masoudifard M, Akbari MT, Zeinali S. Impact of Consanguineous Marriages in GJB2-Related Hearing Loss in the Iranian Population: A Report of a Novel Variant. Genet Test Mol Biomarkers 2011; 15:489-93. [DOI: 10.1089/gtmb.2010.0145] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Nejat Mahdieh
- Kawsar Human Genetic Research Center, Tehran, Iran
- Medical Genetic Group, Ilam University of Medical Sciences, Ilam, Iran
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Bahareh Rabbani
- Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Medical Genetic Group, Ghazvin University of Medical Sciences, Ghazvin, Iran
| | | | | | | | | | | | | | - Mohammad Taghi Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Sirous Zeinali
- Kawsar Human Genetic Research Center, Tehran, Iran
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| |
Collapse
|
57
|
Rodriguez-Paris J, Tamayo ML, Gelvez N, Schrijver I. Allele-specific impairment of GJB2 expression by GJB6 deletion del(GJB6-D13S1854). PLoS One 2011; 6:e21665. [PMID: 21738759 PMCID: PMC3126855 DOI: 10.1371/journal.pone.0021665] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 06/07/2011] [Indexed: 12/24/2022] Open
Abstract
Mutations in the GJB2 gene, which encodes connexin 26, are a frequent cause of congenital non-syndromic sensorineural hearing loss. Two large deletions, del(GJB6-D13S1830) and del(GJB6-D13S1854), which truncate GJB6 (connexin 30), cause hearing loss in individuals homozygous, or compound heterozygous for these deletions or one such deletion and a mutation in GJB2. Recently, we have demonstrated that the del(GJB6-D13S1830) deletion contributes to hearing loss due to an allele-specific lack of GJB2 mRNA expression and not as a result of digenic inheritance, as was postulated earlier. In the current study we investigated the smaller del(GJB6-D13S1854) deletion, which disrupts the expression of GJB2 at the transcriptional level in a manner similar to the more common del(GJB6-D13S1830) deletion. Interestingly, in the presence of this deletion, GJB2 expression remains minimally but reproducibly present. The relative allele-specific expression of GJB2 was assessed by reverse-transcriptase PCR and restriction digestions in three probands who were compound heterozygous for a GJB2 mutation and del(GJB6-D13S1854). Each individual carried a different sequence variant in GJB2. All three individuals expressed the mutated GJB2 allele in trans with del(GJB6-D13S1854), but expression of the GJB2 allele in cis with the deletion was almost absent. Our study clearly corroborates the hypothesis that the del(GJB6-D13S1854), similar to the larger and more common del(GJB6-D13S1830), removes (a) putative cis-regulatory element(s) upstream of GJB6 and narrows down the region of location.
Collapse
Affiliation(s)
- Juan Rodriguez-Paris
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
| | - Marta L. Tamayo
- Instituto de Genética Humana, Universidad Javeriana, Bogotá, Colombia
- Fundación Oftalmológica Nacional, Bogotá, Colombia
| | - Nancy Gelvez
- Instituto de Genética Humana, Universidad Javeriana, Bogotá, Colombia
| | - Iris Schrijver
- Department of Pathology, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California, United States of America
- * E-mail:
| |
Collapse
|
58
|
Cooper DN, Chen JM, Ball EV, Howells K, Mort M, Phillips AD, Chuzhanova N, Krawczak M, Kehrer-Sawatzki H, Stenson PD. Genes, mutations, and human inherited disease at the dawn of the age of personalized genomics. Hum Mutat 2010; 31:631-55. [PMID: 20506564 DOI: 10.1002/humu.21260] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The number of reported germline mutations in human nuclear genes, either underlying or associated with inherited disease, has now exceeded 100,000 in more than 3,700 different genes. The availability of these data has both revolutionized the study of the morbid anatomy of the human genome and facilitated "personalized genomics." With approximately 300 new "inherited disease genes" (and approximately 10,000 new mutations) being identified annually, it is pertinent to ask how many "inherited disease genes" there are in the human genome, how many mutations reside within them, and where such lesions are likely to be located? To address these questions, it is necessary not only to reconsider how we define human genes but also to explore notions of gene "essentiality" and "dispensability."Answers to these questions are now emerging from recent novel insights into genome structure and function and through complete genome sequence information derived from multiple individual human genomes. However, a change in focus toward screening functional genomic elements as opposed to genes sensu stricto will be required if we are to capitalize fully on recent technical and conceptual advances and identify new types of disease-associated mutation within noncoding regions remote from the genes whose function they disrupt.
Collapse
Affiliation(s)
- David N Cooper
- Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
59
|
Mahdieh N, Rabbani B, Wiley S, Akbari MT, Zeinali S. Genetic causes of nonsyndromic hearing loss in Iran in comparison with other populations. J Hum Genet 2010; 55:639-48. [PMID: 20739942 DOI: 10.1038/jhg.2010.96] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
60
|
Majumder P, Crispino G, Rodriguez L, Ciubotaru CD, Anselmi F, Piazza V, Bortolozzi M, Mammano F. ATP-mediated cell-cell signaling in the organ of Corti: the role of connexin channels. Purinergic Signal 2010; 6:167-87. [PMID: 20806010 PMCID: PMC2912995 DOI: 10.1007/s11302-010-9192-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 05/31/2010] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Connexin 26 (Cx26) and connexin 30 (Cx30) form hemichannels that release ATP from the endolymphatic surface of cochlear supporting and epithelial cells and also form gap junction (GJ) channels that allow the concomitant intercellular diffusion of Ca(2+) mobilizing second messengers. Released ATP in turn activates G-protein coupled P2Y(2) and P2Y(4) receptors, PLC-dependent generation of IP(3), release of Ca(2+) from intracellular stores, instigating the regenerative propagation of intercellular Ca(2+) signals (ICS). The range of ICS propagation is sensitive to the concentration of extracellular divalent cations and activity of ectonucleotidases. Here, the expression patterns of Cx26 and Cx30 were characterized in postnatal cochlear tissues obtained from mice aged between P5 and P6. The expression gradient along the longitudinal axis of the cochlea, decreasing from the basal to the apical cochlear turn (CT), was more pronounced in outer sulcus (OS) cells than in inner sulcus (IS) cells. GJ-mediated dye coupling was maximal in OS cells of the basal CT, inhibited by the nonselective connexin channel blocker carbenoxolone (CBX) and absent in hair cells. Photostimulating OS cells with caged inositol (3,4,5) tri-phosphate (IP(3)) resulted in transfer of ICS in the lateral direction, from OS cells to IS cells across the hair cell region (HCR) of medial and basal CTs. ICS transfer in the opposite (medial) direction, from IS cells photostimulated with caged IP(3) to OS cells, occurred mostly in the basal CT. In addition, OS cells displayed impressive rhythmic activity with oscillations of cytosolic free Ca(2+) concentration ([Ca(2+)](i)) coordinated by the propagation of Ca(2+) wavefronts sweeping repeatedly through the same tissue area along the coiling axis of the cochlea. Oscillations evoked by uncaging IP(3) or by applying ATP differed greatly, by as much as one order of magnitude, in frequency and waveform rise time. ICS evoked by direct application of ATP propagated along convoluted cellular paths in the OS, which often branched and changed dynamically over time. Potential implications of these findings are discussed in the context of developmental regulation and cochlear pathophysiology. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s11302-010-9192-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Paromita Majumder
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Giulia Crispino
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Laura Rodriguez
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Catalin Dacian Ciubotaru
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Fabio Anselmi
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Valeria Piazza
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
| | - Mario Bortolozzi
- Dipartimento di Fisica “G. Galilei”, Università di Padova, via Marzolo 8, 35129 Padova, Italy
- Istituto di Neuroscienze, CNR, Padova, Italy
| | - Fabio Mammano
- Istituto Veneto di Medicina Molecolare, Fondazione per la Ricerca Biomedica Avanzata, via G. Orus 2, 35129 Padova, Italy
- Dipartimento di Fisica “G. Galilei”, Università di Padova, via Marzolo 8, 35129 Padova, Italy
- Istituto di Neuroscienze, CNR, Padova, Italy
- Centro Interdipartimentale per lo Studio dei Segnali Cellulari, Università di Padova, via G. Orus 2, 35129 Padova, Italy
- VIMM, Via G. Orus 2, 35129 Padova, Italy
| |
Collapse
|