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Rayani K, Davies B, Cheung M, Comber D, Roberts JD, Tadros R, Green MS, Healey JS, Simpson CS, Sanatani S, Steinberg C, MacIntyre C, Angaran P, Duff H, Hamilton R, Arbour L, Leather R, Seifer C, Fournier A, Atallah J, Kimber S, Makanjee B, Alqarawi W, Cadrin-Tourigny J, Joza J, Gardner M, Talajic M, Bagnall RD, Krahn AD, Laksman ZWM. Identification and in-silico characterization of splice-site variants from a large cardiogenetic national registry. Eur J Hum Genet 2023; 31:512-520. [PMID: 36138163 PMCID: PMC10172209 DOI: 10.1038/s41431-022-01193-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Revised: 08/23/2022] [Accepted: 09/08/2022] [Indexed: 11/08/2022] Open
Abstract
Splice-site variants in cardiac genes may predispose carriers to potentially lethal arrhythmias. To investigate, we screened 1315 probands and first-degree relatives enrolled in the Canadian Hearts in Rhythm Organization (HiRO) registry. 10% (134/1315) of patients in the HiRO registry carry variants within 10 base-pairs of the intron-exon boundary with 78% (104/134) otherwise genotype negative. These 134 probands were carriers of 57 unique variants. For each variant, American College of Medical Genetics and Genomics (ACMG) classification was revisited based on consensus between nine in silico tools. Due in part to the in silico algorithms, seven variants were reclassified from the original report, with the majority (6/7) downgraded. Our analyses predicted 53% (30/57) of variants to be likely/pathogenic. For the 57 variants, an average of 9 tools were able to score variants within splice sites, while 6.5 tools responded for variants outside these sites. With likely/pathogenic classification considered a positive outcome, the ACMG classification was used to calculate sensitivity/specificity of each tool. Among these, Combined Annotation Dependent Depletion (CADD) had good sensitivity (93%) and the highest response rate (131/134, 98%), dbscSNV was also sensitive (97%), and SpliceAI was the most specific (64%) tool. Splice variants remain an important consideration in gene elusive inherited arrhythmia syndromes. Screening for intronic variants, even when restricted to the ±10 positions as performed here may improve genetic testing yield. We compare 9 freely available in silico tools and provide recommendations regarding their predictive capabilities. Moreover, we highlight several novel cardiomyopathy-associated variants which merit further study.
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Affiliation(s)
- Kaveh Rayani
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Brianna Davies
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Matthew Cheung
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Drake Comber
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, Western University, London, ON, Canada
| | - Rafik Tadros
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Martin S Green
- Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | | | | | | | - Christian Steinberg
- Institut Universitaire de Cardiologie et Pneumologie de Quebec, Laval University, Quebec City, QC, Canada
| | - Ciorsti MacIntyre
- Division of Cardiology, QEII Health Sciences Center, Halifax, NS, Canada
| | - Paul Angaran
- St Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Henry Duff
- Libin Cardiovascular Institute, University of Calgary, Calgary, AB, Canada
| | - Robert Hamilton
- Division of Cardiology, The Hospital for Sick Children (SickKids), Toronto, ON, Canada
| | - Laura Arbour
- Division of Medical Genetics, Island Health, Victoria, BC, Canada
| | | | - Colette Seifer
- Section of Cardiology, Department of Internal Medicine, University of Manitoba, Winnipeg, MB, Canada
| | - Anne Fournier
- Division of Pediatric Cardiology, CHU Sainte-Justine, Universite de Montreal, Montreal, QC, Canada
| | - Joseph Atallah
- Division of Pediatric Cardiology, University of Alberta Stollery Children's Hospital, Edmonton, AB, Canada
| | - Shane Kimber
- Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Bhavanesh Makanjee
- Heart Health Institute, Scarborough Health Network, Scarborough, ON, Canada
| | - Wael Alqarawi
- Heart Institute, University of Ottawa, Ottawa, ON, Canada
| | - Julia Cadrin-Tourigny
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Jacqueline Joza
- Division of Cardiology, McGill University Health Centre, Montreal, QC, Canada
| | - Martin Gardner
- Division of Cardiology, QEII Health Sciences Center, Halifax, NS, Canada
| | - Mario Talajic
- Cardiovascular Genetics Center, Montreal Heart Institute, Montreal, QC, Canada
- Department of Medicine, Universite de Montreal, Montreal, QC, Canada
| | - Richard D Bagnall
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Andrew D Krahn
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Zachary W M Laksman
- Center for Cardiovascular Innovation, Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
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Bakur KH, Al-Aama JY, Alhassnan ZN, Brooks H, Clancy T, Manea W, Takroni SA, Ulph F. Exploring the role of Islam on the lived experience of patients with Long QT Syndrome in Saudi Arabia. J Genet Couns 2022; 31:922-936. [PMID: 35194886 DOI: 10.1002/jgc4.1562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/30/2022] [Accepted: 01/31/2022] [Indexed: 11/10/2022]
Abstract
Genetic services are rapidly growing in the Arab world leading to increasing number of patients being diagnosed with genetic disorders. Islam is the only/major religion of the local population in these countries. Muslim patients integrate religion in virtually every aspect of their lives, and it is vital to understand the role of Islam on their coping and decision-making in the context of genetic counseling. This will help provide patients with the most appropriate services aligned to their religious beliefs and will improve outcomes. Increasing numbers of patients are being diagnosed with Long QT syndrome in Saudi Arabia. Using semi-structured interviews, this study explored the role of Islam on the lived experience of 13 Saudi participants diagnosed with autosomal dominant Long QT syndrome (3/13) or who are carriers of Jervell and Lange-Nielsen syndrome (10/13). The interviews investigated how they made sense of living with the condition in light of their religion/spirituality. The data were analyzed using interpretative phenomenological analysis and produced four superordinate themes: 1) Common belief and idiosyncratic interpretation; 2) Using religion to justify positive reframing of current illnesses; 3) Interplay between belief in medicine and in religion; and 4) Complex impact of diagnosis on religiosity. The results show that the participants' idiosyncratic interpretations of the religious principles, not the principles themselves, had an important influence on their coping, medical decision-making, perceptions regarding the cause of their disease, and compliance with medical advice. A novel insight of the current study is that the personal understanding and interpretation of medical information played the greatest role in the decision-making process, and not the religious beliefs. Thus, it is important for health professionals to give patients' information in a manner that is clear and detailed in order for them to facilitate an informed decision, and to ensure that they fully understand the implications.
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Affiliation(s)
- Khadijah H Bakur
- School of Biological Science, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Department of Genetic Medicine, King Abdulaziz University Hospital, Jeddah, Saudi Arabia.,Princess Al-Jawhara Centre of Excellence in Research of Hereditary Disorders, King AbdulAziz University, Jeddah, Saudi Arabia
| | - Jumana Y Al-Aama
- Princess Al-Jawhara Centre of Excellence in Research of Hereditary Disorders, King AbdulAziz University, Jeddah, Saudi Arabia.,Department of Genetic Medicine, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Zuhair N Alhassnan
- Department of Medical Genetics, King Faisal Specialist Hospital & Research Center, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Helen Brooks
- Division of Nursing, Midwifery and Social Work, School of Health Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Tara Clancy
- Manchester Centre for Genomic Medicine, St. Mary's Hospital, Manchester, UK
| | - Waleed Manea
- Heart Center Department, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Saud A Takroni
- Department of Medical Genetics, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Fiona Ulph
- Division of Psychology and Mental Health, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
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Abstract
Congenital hearing loss is the most common birth defect, estimated to affect 2-3 in every 1000 births. Currently there is no cure for hearing loss. Treatment options are limited to hearing aids for mild and moderate cases, and cochlear implants for severe and profound hearing loss. Here we provide a literature overview of the environmental and genetic causes of congenital hearing loss, common animal models and methods used for hearing research, as well as recent advances towards developing therapies to treat congenital deafness. © 2021 The Authors.
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Affiliation(s)
- Justine M Renauld
- Department of Otolaryngology, Head & Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Martin L Basch
- Department of Otolaryngology, Head & Neck Surgery, Case Western Reserve University School of Medicine, Cleveland, Ohio.,Department of Genetics and Genome Sciences, Case Western Reserve School of Medicine, Cleveland, Ohio.,Department of Biology, Case Western Reserve University, Cleveland, Ohio.,Department of Otolaryngology, Head & Neck Surgery, University Hospitals, Cleveland, Ohio
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A cryptic splice-altering KCNQ1 variant in trans with R259L leading to Jervell and Lange-Nielsen syndrome. NPJ Genom Med 2021; 6:21. [PMID: 33664273 PMCID: PMC7933243 DOI: 10.1038/s41525-021-00183-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 01/25/2021] [Indexed: 11/19/2022] Open
Abstract
Here we report an infant with clinical findings suggestive of Jervell and Lange-Nielsen syndrome (JLNS), including a prolonged QT interval (LQTS) and chronic bilateral sensorineural deafness. NGS analysis revealed one known heterozygous pathogenic missense variant, KCNQ1 p.R259L, previously associated with LQTS but insufficient to explain the cardioauditory disorder. In a screening of proximal intronic regions, we found a heterozygous variant, KCNQ1 c.1686−9 T > C, absent from controls and previously undescribed. Several splicing prediction tools returned low scores for this intronic variant. Driven by the proband’s phenotype rather than the neutral predictions, we have characterized this rare intronic variant. Family analysis has shown that the proband inherited the missense and the intronic variants from his mother and father, respectively. A minigene splicing assay revealed that the intronic variant induced an additional transcript, arising from skipping of exon 14, which was translated into a truncated protein in transfected cells. The splice-out of exon 14 creates a frameshift in exon 15 and a stop codon in exon 16, which is the last exon of KCNQ1. This mis-spliced transcript is expected to escape nonsense-mediated decay and predicted to encode a truncated loss-of-function protein, KCNQ1 p.L563Kfs*73. The analysis of endogenous KCNQ1 expression in the blood of the proband’s parents detected the aberrant transcript only in the patient’s father. Taken together, these analyses confirmed the proband’s diagnosis of JLNS1 and indicated that c.1686−9 T > C is a cryptic splice-altering variant, expanding the known genetic spectrum of biallelic KCNQ1 variant combinations leading to JLNS1.
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Dotzler SM, Kim CSJ, Gendron WAC, Zhou W, Ye D, Bos JM, Tester DJ, Barry MA, Ackerman MJ. Suppression-Replacement KCNQ1 Gene Therapy for Type 1 Long QT Syndrome. Circulation 2021; 143:1411-1425. [PMID: 33504163 DOI: 10.1161/circulationaha.120.051836] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Type 1 long QT syndrome (LQT1) is caused by loss-of-function variants in the KCNQ1-encoded Kv7.1 potassium channel α-subunit that is essential for cardiac repolarization, providing the slow delayed rectifier current. No current therapies target the molecular cause of LQT1. METHODS A dual-component suppression-and-replacement (SupRep) KCNQ1 gene therapy was created by cloning a KCNQ1 short hairpin RNA and a short hairpin RNA-immune KCNQ1 cDNA modified with synonymous variants in the short hairpin RNA target site, into a single construct. The ability of KCNQ1-SupRep gene therapy to suppress and replace LQT1-causative variants in KCNQ1 was evaluated by means of heterologous expression in TSA201 cells. For a human in vitro cardiac model, induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were generated from 4 patients with LQT1 (KCNQ1-Y171X, -V254M, -I567S, and -A344A/spl) and an unrelated healthy control. CRISPR-Cas9 corrected isogenic control iPSC-CMs were made for 2 LQT1 lines (correction of KCNQ1-V254M and KCNQ1-A344A/spl). FluoVolt voltage dye was used to measure the cardiac action potential duration (APD) in iPSC-CMs treated with KCNQ1-SupRep. RESULTS In TSA201 cells, KCNQ1-SupRep achieved mutation-independent suppression of wild-type KCNQ1 and 3 LQT1-causative variants (KCNQ1-Y171X, -V254M, and -I567S) with simultaneous replacement of short hairpin RNA-immune KCNQ1 as measured by allele-specific quantitative reverse transcription polymerase chain reaction and Western blot. Using FluoVolt voltage dye to measure the cardiac APD in the 4 LQT1 patient-derived iPSC-CMs, treatment with KCNQ1-SupRep resulted in shortening of the pathologically prolonged APD at both 90% and 50% repolarization, resulting in APD values similar to those of the 2 isogenic controls. CONCLUSIONS This study provides the first proof-of-principle gene therapy for complete correction of long QT syndrome. As a dual-component gene therapy vector, KCNQ1-SupRep successfully suppressed and replaced KCNQ1 to normal wild-type levels. In TSA201 cells, cotransfection of LQT1-causative variants and KCNQ1-SupRep caused mutation-independent suppression and replacement of KCNQ1. In LQT1 iPSC-CMs, KCNQ1-SupRep gene therapy shortened the APD, thereby eliminating the pathognomonic feature of LQT1.
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Affiliation(s)
- Steven M Dotzler
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (S.M.D., C.S.J.K., W.Z., D.Y., J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - C S John Kim
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (S.M.D., C.S.J.K., W.Z., D.Y., J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - William A C Gendron
- Department of Virology & Gene Therapy, Vector and Vaccine Engineering Laboratory (W.A.C.G., M.A.B.), Mayo Clinic, Rochester, MN
| | - Wei Zhou
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (S.M.D., C.S.J.K., W.Z., D.Y., J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - Dan Ye
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (S.M.D., C.S.J.K., W.Z., D.Y., J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - J Martijn Bos
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (S.M.D., C.S.J.K., W.Z., D.Y., J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN.,Department of Cardiovascular Medicine/Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic (J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - David J Tester
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (S.M.D., C.S.J.K., W.Z., D.Y., J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN.,Department of Cardiovascular Medicine/Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic (J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN
| | - Michael A Barry
- Department of Virology & Gene Therapy, Vector and Vaccine Engineering Laboratory (W.A.C.G., M.A.B.), Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory (S.M.D., C.S.J.K., W.Z., D.Y., J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN.,Department of Cardiovascular Medicine/Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic (J.M.B., D.J.T., M.J.A.), Mayo Clinic, Rochester, MN.,Department of Pediatric and Adolescent Medicine/Division of Pediatric Cardiology (M.J.A.), Mayo Clinic, Rochester, MN
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Singer ES, Ingles J, Semsarian C, Bagnall RD. Key Value of RNA Analysis of MYBPC3 Splice-Site Variants in Hypertrophic Cardiomyopathy. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2020; 12:e002368. [PMID: 30645170 DOI: 10.1161/circgen.118.002368] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND MYBPC3 splicing errors are a common cause of hypertrophic cardiomyopathy (HCM). Variants affecting essential splice-site dinucleotides inhibit splicing, whereas the impact of variants at conserved flanking nucleotides is less clear. We evaluated the contribution of MYBPC3 splice-site variants in a large cohort of patients with HCM and assessed the impact on splicing with RNA analysis. METHODS Patients attending a specialized multidisciplinary clinic, with a clinical diagnosis of HCM and genetic testing of at least 46 cardiomyopathy-associated genes, were included. Patients with variants in MYBPC3 splice sites with in silico-predicted effects on splicing were selected. RNA was extracted from fresh venous blood or paraffin-embedded myocardial tissue of the patients, amplified, and sequenced. Variants were classified for pathogenicity using the American College of Medical Genetics and Genomics guidelines. RESULTS We found 29 rare MYBPC3 splice-site variants in 56 of 557 (10%) unrelated HCM probands. Three variants were not predicted to alter RNA splicing, and 13 essential splice dinucleotide, nonsense, and short insertion or deletion variants were not further assessed. RNA analysis was performed on 9 variants (c.654+5G>C, c.772G>A, c.821+3G>T, c.927-9G>A, c.1090G>A, c.1624G>A, c.1624+4A>T, c.3190+5G>A, and c.3491-3C>G), and RNA splicing errors were confirmed for 7. Four variants in 4 families resulted in clinically meaningful reclassifications. CONCLUSIONS After RNA analysis, 4 of 56 (7%) families with MYBPC3 splice-site variants were reclassified from uncertain clinical significance to likely pathogenic. RNA analysis of splice-site variants can assist in understanding pathogenicity and increase the diagnostic yield of genetic testing in HCM.
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Affiliation(s)
- Emma S Singer
- Agnes Ginges Centre for Molecular Cardiology Centenary Institute, The University of Sydney, Australia (E.S.S., J.I., C.S., R.D.B.)
| | - Jodie Ingles
- Agnes Ginges Centre for Molecular Cardiology Centenary Institute, The University of Sydney, Australia (E.S.S., J.I., C.S., R.D.B.).,Faculty of Medicine and Health, The University of Sydney, Australia (J.I., C.S., R.D.B.).,Department of Cardiology, Royal Prince Alfred Hospital, Sydney, Australia (J.I., C.S.)
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology Centenary Institute, The University of Sydney, Australia (E.S.S., J.I., C.S., R.D.B.).,Faculty of Medicine and Health, The University of Sydney, Australia (J.I., C.S., R.D.B.).,Department of Cardiology, Royal Prince Alfred Hospital, Sydney, Australia (J.I., C.S.)
| | - Richard D Bagnall
- Agnes Ginges Centre for Molecular Cardiology Centenary Institute, The University of Sydney, Australia (E.S.S., J.I., C.S., R.D.B.).,Faculty of Medicine and Health, The University of Sydney, Australia (J.I., C.S., R.D.B.)
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Complex aberrant splicing in the induced pluripotent stem cell–derived cardiomyocytes from a patient with long QT syndrome carrying KCNQ1-A344Aspl mutation. Heart Rhythm 2018; 15:1566-1574. [DOI: 10.1016/j.hrthm.2018.05.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Indexed: 02/06/2023]
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Olsson KS, Wålinder O, Jansson U, Wilbe M, Bondeson ML, Stattin EL, Raha-Chowdhury R, Williams R. Common founder effects of hereditary hemochromatosis, Wilson´s disease, the long QT syndrome and autosomal recessive deafness caused by two novel mutations in the WHRN and TMC1 genes. Hereditas 2017; 154:16. [PMID: 29270100 PMCID: PMC5735936 DOI: 10.1186/s41065-017-0052-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/19/2017] [Indexed: 11/22/2022] Open
Abstract
Background Genealogy and molecular genetic studies of a Swedish river valley population resulted in a large pedigree, showing that the hereditary hemochromatosis (HH) HFE/p.C282Y mutation is inherited with other recessive disorders such as Wilson´s disease (WND), a rare recessive disorder of copper overload. The population also contain individuals with the Swedish long QT syndrome (LQTS1) founder mutation (KCNQ1/p.Y111C) which in homozygotes causes the Jervell & Lange Nielsen syndrome (JLNS) and hearing loss (HL). Aims of the study were to test whether the Swedish long QT founder mutation originated in an ancestral HFE family and if carriers had an increased risk for hemochromatosis (HH), a treatable disorder. We also aimed to identify the pathogenic mutation causing the hearing loss disorder segregating in the pedigree. Methods LQTS patients were asked about their ancestry and possible origin in a HH family. They were also offered a predictive testing for the HFE genotype. Church books were screened for families with hearing loss. One HH family had two members with hearing loss, who underwent molecular genetic analysis of the LQTS founder mutation, connexin 26 and thereafter exome sequencing. Another family with hearing loss in repeat generations was also analyzed for connexin 26 and underwent exome sequencing. Results Of nine LQTS patients studied, four carried a HFE mutation (two p.C282Y, two p.H63D), none was homozygous. Three LQTS patients confirmed origin in a female founder ( b 1694, identical to AJ b 1694, a HFE pedigree member from the Fax river. Her descent of 44 HH families, included also 29 families with hearing loss (HL) suggesting JLNS. Eleven LQTS probands confirmed origin in a second founder couple (b 1614/1605) in which the woman b 1605 was identical to a HFE pedigree member from the Fjällsjö river. In her descent there were not only 64 HH, six WND families, one JLNS, but also 48 hearing loss families. Most hearing loss was non syndromic and caused by founder effects of the late 16th century. One was of Swedish origin carrying the WHRN, c.1977delC, (p.S660Afs*30) mutation, the other was a TMC1(NM_138691),c.1814T>C,(p.L605P) mutation, possibly of Finnish origin. Conclusions Deep human HFE genealogies show HFE to be associated with other genetic disorders like Wilson´s disease, LQTS, JLNS, and autosomal recessive hearing loss. Two new homozygous HL mutations in WHRN/p.S660Afs*30 and TMC1/p.L605P were identified,none of them previously reported from Scandinavia. The rarity of JLNS was possibly caused by miscarriage or intrauterine death. Most hearing loss (81.7%) was seen after 1844 when first cousin marriages were permitted. However, only 10 (10.3%) came from 1st cousin unions and only 2 (2.0 %) was born out of wedlock. Electronic supplementary material The online version of this article (10.1186/s41065-017-0052-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- K Sigvard Olsson
- Section of Hematology and Coagulation, Department of Medicine, Sahlgrenska Academy, University of Göteborg, S 413 45 Göteborg, Sweden
| | - Olof Wålinder
- Department of Medicine, Östersund Hospital, Östersund, Sweden
| | - Ulf Jansson
- Department of Clinical Chemistry, Sundsvall Hospital, Sundsvall, Sweden
| | - Maria Wilbe
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Marie-Louise Bondeson
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Eva-Lena Stattin
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Ruma Raha-Chowdhury
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Roger Williams
- Institute of Hepatology London, Foundation for Liver Research, London,SE5 9NT and Faculty of Life Sciences & Medicine, King´s College London, London, UK
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Carrel L, Brown CJ. When the Lyon(ized chromosome) roars: ongoing expression from an inactive X chromosome. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160355. [PMID: 28947654 PMCID: PMC5627157 DOI: 10.1098/rstb.2016.0355] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2017] [Indexed: 12/21/2022] Open
Abstract
A tribute to Mary Lyon was held in October 2016. Many remarked about Lyon's foresight regarding many intricacies of the X-chromosome inactivation process. One such example is that a year after her original 1961 hypothesis she proposed that genes with Y homologues should escape from X inactivation to achieve dosage compensation between males and females. Fifty-five years later we have learned many details about these escapees that we attempt to summarize in this review, with a particular focus on recent findings. We now know that escapees are not rare, particularly on the human X, and that most lack functionally equivalent Y homologues, leading to their increasingly recognized role in sexually dimorphic traits. Newer sequencing technologies have expanded profiling of primary tissues that will better enable connections to sex-biased disorders as well as provide additional insights into the X-inactivation process. Chromosome organization, nuclear location and chromatin environments distinguish escapees from other X-inactivated genes. Nevertheless, several big questions remain, including what dictates their distinct epigenetic environment, the underlying basis of species differences in escapee regulation, how different classes of escapees are distinguished, and the roles that local sequences and chromosome ultrastructure play in escapee regulation.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.
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Affiliation(s)
- Laura Carrel
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, 500 University Drive, Mail code H171, Hershey, PA 17033, USA
| | - Carolyn J Brown
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada BC V6T 1Z3
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Uysal F, Turkgenc B, Toksoy G, Bostan OM, Evke E, Uyguner O, Yakicier C, Kayserili H, Cil E, Temel SG. "Homozygous, and compound heterozygous mutation in 3 Turkish family with Jervell and Lange-Nielsen syndrome: case reports". BMC MEDICAL GENETICS 2017; 18:114. [PMID: 29037160 PMCID: PMC5644177 DOI: 10.1186/s12881-017-0474-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/01/2017] [Indexed: 11/10/2022]
Abstract
BACKGROUND Jervell and Lange-Nielsen syndrome (JLNS) isa recessive model of long QT syndrome which might also be related to possible hearing loss. Although the syndrome has been demonstrated to be originated from homozygous or compound heterozygous mutations in either the KCNQ1 or KCNE1 genes, additional mutations in other genetic loci should be considered, particularly in malignant course patients. CASE PRESENTATIONS Three patients were admitted into hospital due to recurrent seizures/syncope, intrauterine and postnatal bradycardia respectively; moreover all three patients had congenital sensorineural hearing-loss. Their electrocardiograms showed markedly prolonged QT interval. Implantable defibrillator was implanted and left cardiac sympathetic denervation was performed due to the progressive disease in case 1. She had countless ventricular fibrillation and appropriate shock while using an implantable defibrillator. The DNA sequencing analysis of the KCNQ1 gene disclosed a homozygous c.728G > A (p.Arg243His) missense mutation in case1. Further targeted next generation sequencing of cardiac panel comprising 68 gene revealed a heterozygous c.1346 T > G (p.Ile449Arg) variant in RYR2 gene and a heterozygous c.809G > A (p.Cys270Tyr) variant in NKX2-5 gene in the same patient. Additional gene alterations in RYR2 and NKX2-5 genes were thought to be responsible for progressive and malignant course of the disease. As a result of DNA sequencing analysis of KCNQ1 and KCNE1 genes, a compound heterozygosity for two mutations had been detected in KCNQ1 gene in case 2: a maternally derived c.477 + 1G > A splice site mutation and a paternally derived c.520C > T (p.Arg174Cys) missense mutation. Sanger sequencing of KCNQ1 and KCNE1 genes displayed a homozygous c.1097G > A (p.Arg366Gln) mutation in KCNQ1 gene in case 3. β-blocker therapy was initiated to all the index subjects. CONCLUSIONS Three families of JLNS who presented with long QT and deafness and who carry homozygous, or compound heterozygous mutation in KCNQ1 gene were presented in this report. It was emphasized that broad targeted cardiac panels may be useful to predict the outcome especially in patients with unexplained phenotype-genotype correlation. Clinical presentations and molecular findings will be discussed further to clarify the phenotype genotype associations.
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Affiliation(s)
- Fahrettin Uysal
- Department of Pediatric Cardiology, University of Uludag, School of Medicine, Bursa, Turkey
| | | | - Guven Toksoy
- Department of Medical Genetics, Istanbul University, Faculty of Medicine, Istanbul, Turkey
| | - Ozlem M. Bostan
- Department of Pediatric, Cardiology, Uludag University, Faculty of Medicine, Bursa, Turkey
| | - Elif Evke
- Bursa Genetic Diagnostic Center, Bursa, Turkey
| | - Oya Uyguner
- Department of Medical Genetics, Istanbul University, Faculty of Medicine, Istanbul, Turkey
| | - Cengiz Yakicier
- Acibadem Genetic Diagnostic Center, Istanbul, Turkey
- Department of Molecular Biology and Genetic, Acibadem University, Faculty of Science, Istanbul, Turkey
| | - Hulya Kayserili
- Department of Medical Genetics, Istanbul University, Faculty of Medicine, Istanbul, Turkey
- Department of Medical Genetics, Koc University, Faculty of Medicine, Istanbul, Turkey
| | - Ergun Cil
- Department of Pediatric, Cardiology, Uludag University, Faculty of Medicine, Bursa, Turkey
| | - Sehime G. Temel
- Department of Histology& Embryology, Near East University, Faculty of Medicine, Nicosia, North Cyprus
- Department of Medical Genetics, Uludag University, Faculty of Medicine, Bursa, Turkey
- Department of Histology & Embryology, Uludag University, Faculty of Medicine, Bursa, Turkey
- Gorukle campuss, Uludag University, School of Medicine, 16059, Nilufer, Bursa, Turkey
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11
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Zafari Z, Dalili M, Zeinali S, Saber S, Fazeli Far AF, Akbari MT. Identification and characterization of a novel recessive KCNQ1 mutation associated with Romano-Ward Long-QT syndrome in two Iranian families. J Electrocardiol 2017; 50:912-918. [PMID: 29033053 DOI: 10.1016/j.jelectrocard.2017.07.012] [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: 03/22/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND One of the foremost causes of sudden cardiac death in the young is an inherent cardiac arrhythmia known as Long-QT syndrome (LQTS). Whereas heterozygous mutations typically lead to the Romano-Ward type of LQTS, We have provided a further evidence for the recessive transmission of a novel KCNQ1 gene mutation in two consanguineous families for the first time in Iran. METHODS Next generation sequencing, DNA Sanger sequencing and haplotype analysis were performed for genotype determination. Twelve different in silico tools were used for predicting the variant pathogenecity along with the family and population study. RESULTS A novel recessive KCNQ1 variant (p.D564G) was revealed in none of the unrelated healthy individuals but four patients in two apparently unrelated families. The variant was classified as a likely pathogenic mutation by combining the resulted criteria for the changed amino acid. CONCLUSIONS Identification of the novel mutation not only supports the genetic testing as a definitive diagnostic tool for detection of at risk family members, but also emphasizes its screening in Iranian LQTS patients as this mutation is very likely a founder mutation in Iran.
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Affiliation(s)
- Zahra Zafari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Dalili
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Sirus Zeinali
- Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Siamak Saber
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Amir Farjam Fazeli Far
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Taghi Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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12
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Harmer SC, Tinker A. The impact of recent advances in genetics in understanding disease mechanisms underlying the long QT syndromes. Biol Chem 2017; 397:679-93. [PMID: 26910742 DOI: 10.1515/hsz-2015-0306] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/18/2016] [Indexed: 11/15/2022]
Abstract
Long QT syndrome refers to a characteristic abnormality of the electrocardiogram and it is associated with a form of ventricular tachycardia known as torsade-de-pointes and sudden arrhythmic death. It can occur as part of a hereditary syndrome or can be acquired usually because of drug administration. Here we review recent genetic, molecular and cellular discoveries and outline how they have furthered our understanding of this disease. Specifically we focus on compound mutations, genome wide association studies of QT interval, modifier genes and the therapeutic implications of this recent work.
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13
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Bdier AY, Al-Ghamdi S, Verma PK, Dagriri K, Alshehri B, Jiman OA, Ahmed SE, Wilde AAM, Bhuiyan ZA, Al-Aama JY. Autosomal recessive long QT syndrome, type 1 in eight families from Saudi Arabia. Mol Genet Genomic Med 2017; 5:592-601. [PMID: 28944242 PMCID: PMC5606890 DOI: 10.1002/mgg3.305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/18/2017] [Accepted: 05/22/2017] [Indexed: 01/08/2023] Open
Abstract
Background One of the most common primary cardiac arrhythmia syndromes is autosomal dominant long QT syndrome, type 1 (LQT1), chiefly caused by mono‐allelic mutations in the KCNQ1 gene. Bi‐allelic mutations in the KCNQ1 gene are causal to Jervell and Lange‐Nielsen syndrome (JLNS), characterized by severe and early‐onset arrhythmias with prolonged QTc interval on surface ECG and sensorineural deafness. Occasionally, bi‐allelic mutations in KCNQ1 are also found in patients without any deafness, referred to as autosomal recessive long QT syndrome, type 1 (AR LQT1). Methods We used Sanger sequencing to detect the pathogenic mutations in KCNQ1 gene in eight families from Saudi Arabia with autosomal recessive LQT1. Results We have detected pathogenic mutations in all eight families, two of the mutations are founder mutations, which are c.387‐5T>A and p.Val172Met/p.Arg293Cys (in cis). QTc and cardiac phenotype was found to be pronounced in all the probands comparable to the cardiac phenotype in JLNS patients. Heterozygous carriers for these mutations did not exhibit any clinical phenotype, but a significant number of them have sinus bradycardia. Conclusion To the best of our knowledge, this is the first description of a large series of patients with familial autosomal recessive LQT, type 1. These mutations could be used for targeted screening in cardiac arrhythmia patients in Saudi Arabia and in people of Arabic ancestry.
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Affiliation(s)
- Amnah Y Bdier
- Department of Biological SciencesFaculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia.,Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Saleh Al-Ghamdi
- Department of Genetic MedicineKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Prashant K Verma
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia.,Department of CardiologyNGHRiyadhSaudi Arabia
| | - Khalid Dagriri
- Department of Pediatric CardiologyPrince Sultan Cardiac CenterRiyadhSaudi Arabia
| | - Bandar Alshehri
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Omamah A Jiman
- Department of Genetic MedicineKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Sherif E Ahmed
- Department of Biological SciencesFaculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia.,Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia.,Department of GeneticsFaculty of AgricultureAin shams UniversityCairoEgypt
| | - Arthur A M Wilde
- Department of CardiologyAcademic Medical CenterUniversity of AmsterdamAmsterdamthe Netherlands
| | - Zahurul A Bhuiyan
- Laboratoire de Génétique MoléculaireService de médecine génétiqueCHUVLausanneSwitzerland
| | - Jumana Y Al-Aama
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary DisordersKing Abdulaziz UniversityJeddahSaudi Arabia.,Department of CardiologyNGHRiyadhSaudi Arabia
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14
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Al-Hassnan ZN, Al-Fayyadh M, Al-Ghamdi B, Shafquat A, Mallawi Y, Al-Hadeq F, Tulbah S, Shinwari ZMA, Almesned A, Alakhfash A, Al Fadly F, Hersi AS, Alhayani A, Al-Hashem A, Arafah D, Dzimiri N, Meyer B, Rababh M, Al-Manea W. Clinical profile and mutation spectrum of long QT syndrome in Saudi Arabia: The impact of consanguinity. Heart Rhythm 2017; 14:1191-1199. [PMID: 28438721 DOI: 10.1016/j.hrthm.2017.04.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Congenital long QT syndrome (LQTS) is an inherited, potentially fatal arrhythmogenic disorder. At least 16 genes have been implicated in LQTS; the yield of genetic analysis of 3 genes (KCNQ1, KCNH2, and SCN5A) is about 70%, with KCNQ1 mutations accounting for ∼50% of positive cases. LQTS is mostly inherited in an autosomal dominant pattern. Systemic analysis of LQTS has not been previously conducted in a population with a high degree of consanguinity. OBJECTIVES To describe the clinical and molecular profiles of LQTS in the highly consanguineous Saudi population. METHODS Fifty-six Saudi families with LQTS were consecutively recruited and evaluated. Sequencing of KCNQ1, KCNH2, and SCN5A genes was conducted on all probands, followed by screening of family relatives. RESULTS Genetic analysis was positive in 32 (57.2%) families, with mutations in KCNQ1 identified in 28 families (50%). Surprisingly, 17 (53.1%) probands were segregating homozygous mutations. Family screening identified 123 individuals with mutations; 89 (72.4%) were heterozygous, 23 (18.7%) were homozygous, and 11 (8.9%) were compound heterozygous. Compared to heterozygous, the phenotype was more severe in homozygous individuals, with cardiac symptoms in 78.3% (vs 12.4%), family history of sudden death in 64.7% (vs 44.4%), and prolonged QT interval in 100% (vs 43.8%). Congenital deafness was found in 11 (47.8%) homozygous probands. CONCLUSION Our study provides insight into the clinical and molecular profiles of LQTS in a consanguineous population. It underscores the importance of preemptive management in homozygous patients with LQTS and the value of clinical and molecular screening of at-risk relatives.
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Affiliation(s)
- Zuhair N Al-Hassnan
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia; College of Medicine, Alfaisal University, Riyadh, Saudi Arabia; Department of Medical Genetics, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia.
| | - Majid Al-Fayyadh
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia; Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Bander Al-Ghamdi
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Azam Shafquat
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Yaseen Mallawi
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Faten Al-Hadeq
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Sahar Tulbah
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Zarghuna M A Shinwari
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | | | | | - Fadel Al Fadly
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Ahmed S Hersi
- Cardiac Sciences Department, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | | | - Amal Al-Hashem
- Department of Pediatrics, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - Dia Arafah
- Maternity and Children Hospital, Makkah, Saudi Arabia
| | - Nduna Dzimiri
- Department of Genetics, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Brian Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Monther Rababh
- Cardiovascular Genetics Program, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
| | - Waleed Al-Manea
- Heart Center, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia
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15
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Kapplinger JD, Erickson A, Asuri S, Tester DJ, McIntosh S, Kerr CR, Morrison J, Tang A, Sanatani S, Arbour L, Ackerman MJ. KCNQ1 p.L353L affects splicing and modifies the phenotype in a founder population with long QT syndrome type 1. J Med Genet 2017; 54:390-398. [PMID: 28264985 PMCID: PMC5502312 DOI: 10.1136/jmedgenet-2016-104153] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 11/30/2016] [Accepted: 12/19/2016] [Indexed: 12/23/2022]
Abstract
Background Variable expressivity and incomplete penetrance between individuals with identical long QT syndrome (LQTS) causative mutations largely remain unexplained. Founder populations provide a unique opportunity to explore modifying genetic effects. We examined the role of a novel synonymous KCNQ1 p.L353L variant on the splicing of exon 8 and on heart rate corrected QT interval (QTc) in a population known to have a pathogenic LQTS type 1 (LQTS1) causative mutation, p.V205M, in KCNQ1-encoded Kv7.1. Methods 419 adults were genotyped for p.V205M, p.L353L and a previously described QTc modifier (KCNH2-p.K897T). Adjusted linear regression determined the effect of each variant on QTc, alone and in combination. In addition, peripheral blood RNA was extracted from three controls and three p.L353L-positive individuals. The mutant transcript levels were assessed via qPCR and normalised to overall KCNQ1 transcript levels to assess the effect on splicing. Results For women and men, respectively, p.L353L alone conferred a 10.0 (p=0.064) ms and 14.0 (p=0.014) ms increase in QTc and in men only a significant interaction effect in combination with the p.V205M (34.6 ms, p=0.003) resulting in a QTc of ∼500 ms. The mechanism of p.L353L's effect was attributed to approximately threefold increase in exon 8 exclusion resulting in ∼25% mutant transcripts of the total KCNQ1 transcript levels. Conclusions Our results provide the first evidence that synonymous variants outside the canonical splice sites in KCNQ1 can alter splicing and clinically impact phenotype. Through this mechanism, we identified that p.L353L can precipitate QT prolongation by itself and produce a clinically relevant interactive effect in conjunction with other LQTS variants.
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Affiliation(s)
- Jamie D Kapplinger
- Mayo Medical School, Mayo Clinic, Rochester, Minnesota, USA.,Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota, USA
| | - Anders Erickson
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - Sirisha Asuri
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - David J Tester
- Division of Heart Rhythm Services, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Sarah McIntosh
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Charles R Kerr
- Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Julie Morrison
- Gitxsan Health Society, Hazelton, British Columbia, Canada
| | - Anthony Tang
- Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Shubhayan Sanatani
- Division of Cardiology, Department of Pediatrics, University of British Columbia, BC Children's Hospital, Vancouver, British Columbia, Canada
| | - Laura Arbour
- Division of Medical Sciences, University of Victoria, Victoria, British Columbia, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael J Ackerman
- Mayo Medical School, Mayo Clinic, Rochester, Minnesota, USA.,Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota, USA.,Division of Heart Rhythm Services, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA.,Division of Pediatric Cardiology, Department of Pediatrics, Mayo Clinic, Rochester, Minnesota, USA
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16
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Singh A, Prasad R, Singh R, Kapoor S, Bhuiyan ZA, Mishra OP. Genetic Analysis of Jervel and Lange Nielsen Syndrome with a Novel Mutation in KCNQ1 Gene. Indian J Pediatr 2016; 83:1038-9. [PMID: 26939673 DOI: 10.1007/s12098-016-2072-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/17/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Ankur Singh
- Genetic and Metabolic Clinic, Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India.
| | - Rajniti Prasad
- Genetic and Metabolic Clinic, Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India
| | - Royana Singh
- Department of Anatomy, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Seema Kapoor
- Department of Pediatrics, Maulana Azad Medical College and Associated Lok Nayak Hospital, New Delhi, India
| | - Zahurul A Bhuiyan
- Molecular Diagnostic Laboratory, Service of Medical Genetics, University Hospital Lausanne (CHUV), Lausanne, Switzerland
| | - Om Prakash Mishra
- Genetic and Metabolic Clinic, Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India
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17
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Vyas B, Puri RD, Namboodiri N, Nair M, Sharma D, Movva S, Saxena R, Bohora S, Aggarwal N, Vora A, Kumar J, Singh T, Verma IC. KCNQ1 mutations associated with Jervell and Lange-Nielsen syndrome and autosomal recessive Romano-Ward syndrome in India-expanding the spectrum of long QT syndrome type 1. Am J Med Genet A 2016; 170:1510-9. [PMID: 27041150 DOI: 10.1002/ajmg.a.37636] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 03/07/2016] [Indexed: 01/07/2023]
Abstract
Long QT syndrome type 1 (LQT1) is the most common type of all Long QT syndromes (LQTS) and occurs due to mutations in KCNQ1. Biallelic mutations with deafness is called Jervell and Lange-Nielsen syndrome (JLNS) and without deafness is autosomal recessive Romano-Ward syndrome (AR RWS). In this prospective study, we report biallelic mutations in KCNQ1 in Indian patients with LQT1 syndrome. Forty patients with a clinical diagnosis of LQT1 syndrome were referred for molecular testing. Of these, 18 were excluded from the analysis as they did not fulfill the inclusion criteria of broad T wave ECG pattern of the study. Direct sequencing of KCNQ1 was performed in 22 unrelated probands, parents and at-risk family members. Mutations were identified in 17 patients, of which seven had heterozygous mutations and were excluded in this analysis. Biallelic mutations were identified in 10 patients. Five of 10 patients did not have deafness and were categorized as AR RWS, the rest being JLNS. Eight mutations identified in this study have not been reported in the literature and predicted to be pathogenic by in silico analysis. We hypothesize that the homozygous biallelic mutations identified in 67% of families was due to endogamous marriages in the absence of consanguinity. This study presents biallelic gene mutations in KCNQ1 in Asian Indian patients with AR JLNS and RWS. It adds to the scant worldwide literature of mutation studies in AR RWS. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Bijal Vyas
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Ratna D Puri
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Narayanan Namboodiri
- Department of Cardiology, Sree Chitra Institute for Medical Sciences & Technology, Kerala, India
| | - Mohan Nair
- Department of Cardiology, Holy Family Hospital, Delhi, India
| | - Deepak Sharma
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Sireesha Movva
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Renu Saxena
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
| | - Shomu Bohora
- Department of Cardiology, Baroda Heart Institute & Research Centre, Gujarat, India
| | - Neeraj Aggarwal
- Department of Paediatric Cardiology, Sir Ganga Ram Hospital, Delhi, India
| | - Amit Vora
- Department of Cardiology, Glenmark Cardiac Centre, Mumbai, Maharashtra, India
| | - Jatinder Kumar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - Tarandeep Singh
- Department of Cardiology, U N Mehta Institute of Cardiology & Research Centre, Gujarat, India
| | - Ishwar C Verma
- Centre of Medical Genetics, Sir Ganga Ram Hospital, Delhi, India
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18
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Asadi M, Foo R, Samienasab MR, Salehi AR, Kheirollahi M, Khanahmad H, Salehi R. Genetic analysis of Iranian family with hereditary cardiac arrhythmias by next generation sequencing. Adv Biomed Res 2016; 5:55. [PMID: 27110552 PMCID: PMC4817390 DOI: 10.4103/2277-9175.178801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/15/2015] [Indexed: 12/05/2022] Open
Abstract
Background: Cardiac arrhythmias are responsible for several cases of syncope and sudden cardiac death annually worldwide. Due to overlapping clinical symptoms in some cardiac arrhythmias genetic studies would help to confirm the primary clinical diagnosis made on the basis of solely clinical findings. In addition clinical management of the patient, family screening and provide appropriate counseling and risk assessment for the family members are other advantages of genetic study. Materials and Methods: Totally nine patients from a family included in this study. The primary diagnosis on the basis of clinical findings was second-degree atrioventricular (AV) block for this family. Mutation in SCN5A gene is frequently reported for second-degree AV block and hence the gene was analyzed using whole gene sequencing but no mutation was detected. Subsequently, the samples were subjected to customized Ampliseq 77 gene panel using next generation sequencing to detect the underlying molecular defects. Results: We found c. 5570T>A missense mutation in ANK2 gene for this family. Based on the Online Mendelian Inheritance in Man, ANK2 gene and the mutation detected correspond to long QT syndrome type 4. Conclusion: This mutation, although already known in other populations, but is reported for the first time in Iranian patients with cardiac arrhythmias. As the case with this family, genetic analysis of patients with cardiac arrhythmias would be helpful in reassessment of clinical diagnosis and therefore would help for patients’ management and in some cases re-evaluation of ongoing treatment may be needed.
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Affiliation(s)
- Marzieh Asadi
- Department of Genetic and Molecular Biology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Roger Foo
- Cardiovascular Research Institute, and Genome Institute of Singapore, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Mohammad Reza Samienasab
- Department of Cardiovascular Disease, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ahmad Reza Salehi
- Department of Genetic and Molecular Biology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Majid Kheirollahi
- Department of Genetic and Molecular Biology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hossein Khanahmad
- Department of Genetic and Molecular Biology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Rasoul Salehi
- Department of Genetic and Molecular Biology, Isfahan University of Medical Sciences, Isfahan, Iran
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19
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Tadmouri GO, Sastry KS, Chouchane L. Arab gene geography: From population diversities to personalized medical genomics. Glob Cardiol Sci Pract 2014; 2014:394-408. [PMID: 25780794 PMCID: PMC4355514 DOI: 10.5339/gcsp.2014.54] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 12/11/2014] [Indexed: 12/20/2022] Open
Abstract
Genetic disorders are not equally distributed over the geography of the Arab region. While a number of disorders have a wide geographical presence encompassing 10 or more Arab countries, almost half of these disorders occur in a single Arab country or population. Nearly, one-third of the genetic disorders in Arabs result from congenital malformations and chromosomal abnormalities, which are also responsible for a significant proportion of neonatal and perinatal deaths in Arab populations. Strikingly, about two-thirds of these diseases in Arab patients follow an autosomal recessive mode of inheritance. High fertility rates together with increased consanguineous marriages, generally noticed in Arab populations, tend to increase the rates of genetic and congenital abnormalities. Many of the nearly 500 genes studied in Arab people revealed striking spectra of heterogeneity with many novel and rare mutations causing large arrays of clinical outcomes. In this review we provided an overview of Arab gene geography, and various genetic abnormalities in Arab populations, including disorders of blood, metabolic, circulatory and neoplasm, and also discussed their associated molecules or genes responsible for the cause of these disorders. Although studying Arab-specific genetic disorders resulted in a high value knowledge base, approximately 35% of genetic diseases in Arabs do not have a defined molecular etiology. This is a clear indication that comprehensive research is required in this area to understand the molecular pathologies causing diseases in Arab populations.
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Affiliation(s)
| | - Konduru S Sastry
- Laboratory of Genetic Medicine and Immunology, Weill Cornell Medical College in Qatar, Qatar Foundation, Doha, Qatar
| | - Lotfi Chouchane
- Laboratory of Genetic Medicine and Immunology, Weill Cornell Medical College in Qatar, Qatar Foundation, Doha, Qatar
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Winbo A, Rydberg A. Vestibular dysfunction is a clinical feature of the Jervell and Lange-Nielsen Syndrome. SCAND CARDIOVASC J 2014; 49:7-13. [DOI: 10.3109/14017431.2014.988172] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Annika Winbo
- Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden
| | - Annika Rydberg
- Department of Clinical Sciences, Pediatrics, Umeå University, Umeå, Sweden
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Aburawi EH, Aburawi HE, Bagnall KM, Bhuiyan ZA. Molecular insight into heart development and congenital heart disease: An update review from the Arab countries. Trends Cardiovasc Med 2014; 25:291-301. [PMID: 25541328 DOI: 10.1016/j.tcm.2014.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 11/14/2014] [Accepted: 11/14/2014] [Indexed: 02/07/2023]
Abstract
Congenital heart defect (CHD) has a major influence on affected individuals as well as on the supportive and associated environment such as the immediate family. Unfortunately, CHD is common worldwide with an incidence of approximately 1% and consequently is a major health concern. The Arab population has a high rate of consanguinity, fertility, birth, and annual population growth, in addition to a high incidence of diabetes mellitus and obesity. All these factors may lead to a higher incidence and prevalence of CHD within the Arab population than in the rest of the world, making CHD of even greater concern. Sadly, most Arab countries lack appropriate public health measures directed toward the control and prevention of congenital malformations and so the importance of CHD within the population remains unknown but is thought to be high. In approximately 85% of CHD patients, the multifactorial theory is considered as the pathologic basis. The genetic risk factors for CHD can be attributed to large chromosomal aberrations, copy number variations (CNV) of particular regions in the chromosome, and gene mutations in specific nuclear transcription pathways and in the genes that are involved in cardiac structure and development. The application of modern molecular biology techniques such as high-throughput nucleotide sequencing and chromosomal array and methylation array all have the potential to reveal more genetic defects linked to CHD. Exploring the genetic defects in CHD pathology will improve our knowledge and understanding about the diverse pathways involved and also about the progression of this disease. Ultimately, this will link to more efficient genetic diagnosis and development of novel preventive therapeutic strategies, as well as gene-targeted clinical management. This review summarizes our current understanding of the molecular basis of normal heart development and the pathophysiology of a wide range of CHD. The risk factors that might account for the high prevalence of CHD within the Arab population and the measures required to be undertaken for conducting research into CHD in Arab countries will also be discussed.
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Affiliation(s)
- Elhadi H Aburawi
- Department of Pediatrics, United Arab Emirates University, Al-Ain, UAE
| | - Hanan E Aburawi
- Department of Biology, Faculty of Sciences, United Arab Emirates University, Al-Ain, UAE
| | - Keith M Bagnall
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, UAE
| | - Zahurul A Bhuiyan
- Laboratoire de Diagnostic Moléculaire, Service de Génétique Médicale, BH19_512, Centre Hospitalier Universitaire Vaudois (CHUV), Rue du Bugnon 46, Lausanne CH-1011, Switzerland.
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Cellular mechanisms underlying the increased disease severity seen for patients with long QT syndrome caused by compound mutations in KCNQ1. Biochem J 2014; 462:133-42. [PMID: 24912595 DOI: 10.1042/bj20140425] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The KCNQ1 (potassium voltage-gated channel, KQT-like subfamily, member 1) gene encodes the Kv7.1 potassium channel which forms a complex with KCNE1 (potassium voltage-gated channel Isk-related family member 1) in the human heart to produce the repolarizing IKs (slow delayed rectifier potassium current). Mutations in KCNQ1 can perturb IKs function and cause LQT1 (long QT syndrome type 1). In LQT1, compound mutations are relatively common and are associated with increased disease severity. LQT1 compound mutations have been shown to increase channel dysfunction, but whether other disease mechanisms, such as defective channel trafficking, contribute to the increase in arrhythmic risk has not been determined. Using an imaging-based assay we investigated the effects of four compound heterozygous mutations (V310I/R594Q, A341V/P127T, T391I/Q530X and A525T/R518X), one homozygous mutation (W248F) and one novel compound heterozygous mutation (A178T/K422fs39X) (where fs denotes frameshift) on channel trafficking. By analysing the effects in the equivalent of a homozygous, heterozygous and compound heterozygous condition, we identify three different types of behaviour. A341V/P127T and W248F/W248F had no effect, whereas V310I/R594Q had a moderate, but not compound, effect on channel trafficking. In contrast, T391I/Q530X, A525T/R518X and A178T/K422fs39X severely disrupted channel trafficking when expressed in compound form. In conclusion, we have characterized the disease mechanisms for six LQT1 compound mutations and report that, for four of these, defective channel trafficking underlies the severe clinical phenotype.
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Imai M, Nakajima T, Kaneko Y, Niwamae N, Irie T, Ota M, Iijima T, Tange S, Kurabayashi M. A novel KCNQ1 splicing mutation in patients with forme fruste LQT1 aggravated by hypokalemia. J Cardiol 2014; 64:121-6. [DOI: 10.1016/j.jjcc.2013.11.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/10/2013] [Accepted: 11/20/2013] [Indexed: 10/25/2022]
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Al-Aama J, Al-Ghamdi S, Bdier A, AlQarawi A, Jiman O, Al-Aama N, Al-Aata J, Wilde A, Bhuiyan Z. Genotype-phenotype analysis of Jervell and Lange-Nielsen syndrome in six families from Saudi Arabia. Clin Genet 2013; 87:74-9. [DOI: 10.1111/cge.12330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 11/28/2013] [Accepted: 12/02/2013] [Indexed: 11/29/2022]
Affiliation(s)
- J.Y. Al-Aama
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - S. Al-Ghamdi
- Department of Pediatric Cardiology; Prince Sultan Cardiac Center; Riyadh Saudi Arabia
| | - A.Y. Bdier
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - A. AlQarawi
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - O.A. Jiman
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - N. Al-Aama
- Department of Cardiology; King Abdulaziz University Hospital; Jeddah Saudi Arabia
| | - J. Al-Aata
- Department of Cardiology; King Abdulaziz University Hospital; Jeddah Saudi Arabia
| | - A.A.M. Wilde
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
- Department of Cardiology, Academic Medical Center; University of Amsterdam; Amsterdam the Netherlands
| | - Z.A. Bhuiyan
- Laboratoire de Génétique Moléculaire, Service de Génétique Médicale; CHUV; Lausanne Switzerland
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Bhuiyan ZA, Al-Shahrani S, Al-Aama J, Wilde AAM, Momenah TS. Congenital Long QT Syndrome: An Update and Present Perspective in Saudi Arabia. Front Pediatr 2013; 1:39. [PMID: 24400285 PMCID: PMC3864249 DOI: 10.3389/fped.2013.00039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/05/2013] [Indexed: 12/14/2022] Open
Abstract
Primary cardiac arrhythmias are often caused by defects, predominantly in the genes responsible for generation of cardiac electrical potential, i.e., cardiac rhythm generation. Due to the variability in underlying genetic defects, type, and location of the mutations and putative modifiers, clinical phenotypes could be moderate to severe, even absent in many individuals. Clinical presentation and severity could be quite variable, syncope, or sudden cardiac death could also be the first and the only manifestation in a patient who had previously no symptoms at all. Despite usual familial occurrence of such cardiac arrhythmias, disease causal genetic defects could also be de novo in significant number of patients. Long QT syndrome (LQTS) is the most eloquently investigated primary cardiac rhythm disorder. A genetic defect can be identified in ∼70% of definitive LQTS patients, followed by Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) and Brugada syndrome (BrS), where a genetic defect is found in <40% cases. In addition to these widely investigated hereditary arrhythmia syndromes, there remain many other relatively less common arrhythmia syndromes, where researchers also have unraveled the genetic etiology, e.g., short QT syndrome (SQTS), sick sinus syndrome (SSS), cardiac conduction defect (CCD), idiopathic ventricular fibrillation (IVF), early repolarization syndrome (ERS). There exist also various other ill-defined primary cardiac rhythm disorders with strong genetic and familial predisposition. In the present review we will focus on the genetic basis of LQTS and its clinical management. We will also discuss the presently available genetic insight in this context from Saudi Arabia.
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Affiliation(s)
- Zahurul A. Bhuiyan
- Laboratoire de Génétique Moléculaire, Service de Génétique Médicale, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Safar Al-Shahrani
- Department of Pediatrics, Faculty of Medicine, King Khalid University, Abha, Saudi Arabia
| | - Jumana Al-Aama
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders, Jeddah, Saudi Arabia
- Department of Genetic Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Arthur A. M. Wilde
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders, Jeddah, Saudi Arabia
- Department of Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, Netherlands
| | - Tarek S. Momenah
- Department of Pediatric Cardiology, King Fahad Medical City, Riyadh, Saudi Arabia
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Al-Aama J, Al-Ghamdi S, Bdier A, Wilde A, Bhuiyan ZA. De novomutation in theKCNQ1gene causal to Jervell and Lange-Nielsen syndrome. Clin Genet 2013; 86:492-5. [DOI: 10.1111/cge.12300] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/02/2013] [Accepted: 10/09/2013] [Indexed: 11/27/2022]
Affiliation(s)
- J.Y. Al-Aama
- Department of Genetic Medicine; King Abdulaziz University Hospital; Jeddah Saudi Arabia
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - S. Al-Ghamdi
- Department of Pediatric Cardiology; Prince Sultan Cardiac Center; Riyadh Saudi Arabia
| | - A.Y. Bdier
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
| | - A.A.M. Wilde
- Princess Al Jawhara Albrahim Center of Excellence in Research of Hereditary Disorders; King Abdulaziz University; Jeddah Saudi Arabia
- Department of Cardiology, Academic Medical Center; University of Amsterdam; Amsterdam the Netherlands
| | - Zahurul A. Bhuiyan
- Laboratoire de Génétique Moléculaire, Service de Génétique Médicale; CHUV; Lausanne Switzerland
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Giudicessi JR, Ackerman MJ. Prevalence and potential genetic determinants of sensorineural deafness in KCNQ1 homozygosity and compound heterozygosity. ACTA ACUST UNITED AC 2013; 6:193-200. [PMID: 23392653 DOI: 10.1161/circgenetics.112.964684] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND- Homozygous or compound heterozygous mutations in KCNQ1 cause Jervell and Lange-Nielsen syndrome, a rare, autosomal-recessive form of long-QT syndrome characterized by deafness, marked QT prolongation, and a high risk of sudden death. However, it is not understood why some individuals with mutations on both KCNQ1 alleles present without deafness. In this study, we sought to determine the prevalence and genetic determinants of this phenomenon in a large referral population of patients with long-QT syndrome. METHODS AND RESULTS- A retrospective analysis of all patients with long-QT syndrome evaluated from July 1998 to April 2012 was used to identify those with ≥1 KCNQ1 mutation. Of the 249 KCNQ1-positive patients identified, 15 (6.0%) harbored a rare putative pathogenic mutation on both KCNQ1 alleles. Surprisingly, 11 of these patients (73%) presented without the sensorineural deafness associated with Jervell and Lange-Nielsen syndrome. The degree of QT-interval prolongation and the number of breakthrough cardiac events were similar between patients with and without deafness. Interestingly, truncating mutations were more prevalent in patients with Jervell and Lange-Nielsen syndrome (79%) than in nondeaf patients (36%; P<0.001) derived from this study and those in the literature. CONCLUSIONS- In this study, we provide evidence that the recessive inheritance of a severe long-QT syndrome type 1 phenotype in the absence of an auditory phenotype may represent a more common pattern of long-QT syndrome inheritance than previously anticipated and that these cases should be treated as a higher-risk long-QT syndrome subset similar to their Jervell and Lange-Nielsen syndrome counterparts. Furthermore, mutation type may serve as a genetic determinant of deafness, but not cardiac expressivity, in individuals harboring ≥1 KCNQ1 mutation on each allele.
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Gao Y, Li C, Liu W, Wu R, Qiu X, Liang R, Li L, Zhang L, Hu D. Genotype-phenotype analysis of three Chinese families with Jervell and Lange-Nielsen syndrome. J Cardiovasc Dis Res 2012; 3:67-75. [PMID: 22629021 PMCID: PMC3354473 DOI: 10.4103/0975-3583.95357] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Long QT syndrome (LQTS) is characterized by QT prolongation, syncope and sudden death. This study aims to explore the causes, clinical manifestations and therapeutic outcomes of Jervell and Lange-Nielsen syndrome (JLNS), a rare form of LQTS with congenital sensorineural deafness, in Chinese individuals. MATERIALS AND METHODS Three JLNS kindreds from the Chinese National LQTS Registry were investigated. Mutational screening of KCNQ1 and KCNE1 genes was performed by polymerase chain reaction and direct DNA sequence analysis. LQTS phenotype and therapeutic outcomes were evaluated for all probands and family members. RESULTS We identified 7 KCNQ1 mutations. c.1032_1117dup (p.Ser373TrpfsX10) and c.1319delT (p.Val440AlafsX26) were novel, causing JLNS in a 16-year-old boy with a QTc (QT interval corrected for heart rate) of 620 ms and recurrent syncope. c.605-2A>G and c.815G>A (p.Gly272Asp) caused JLNS in a 12-year-old girl and her 5-year-old brother, showing QTc of 590 to 600 ms and recurrent syncope. The fourth JLNS case, a 46-year-old man carrying c.1032G>A (p.Ala344Alasp) and c.569G>A (p.Arg190Gln) and with QTc of 460 ms, has been syncope-free since age 30. His 16-year-old daughter carries novel missense mutation c.574C>T (p.Arg192Cys) and c.1032G>A(p.Ala344Alasp) and displayed a severe phenotype of Romano-Ward syndrome (RWS) characterized by a QTc of 530 ms and recurrent syncope with normal hearing. Both the father and daughter also carried c.253G>A (p.Asp85Asn; rs1805128), a rare single nucleotide polymorphism (SNP) on KCNE1. Bizarre T waves were seen in 3/4 JLNS patients. Symptoms were improved and T wave abnormalities became less abnormal after appropriate treatment. CONCLUSION This study broadens the mutation and phenotype spectrums of JLNS. Compound heterozygous KCNQ1 mutations can result in both JLNS and severe forms of RWS in Chinese individuals.
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Affiliation(s)
- Yuanfeng Gao
- Heart Center, Peking University People's Hospital, Beijing - 100 044, P. R. China
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Winbo A, Stattin EL, Diamant UB, Persson J, Jensen SM, Rydberg A. Prevalence, mutation spectrum, and cardiac phenotype of the Jervell and Lange-Nielsen syndrome in Sweden. Europace 2012; 14:1799-806. [PMID: 22539601 DOI: 10.1093/europace/eus111] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AIMS To explore the national prevalence, mutation spectrum, cardiac phenotype, and outcome of the uncommon Jervell and Lange-Nielsen syndrome (JLNS), associated with a high risk of sudden cardiac death. METHODS AND RESULTS A national inventory of clinical JLNS cases was performed. Genotype and area of origin were ascertained in index families. Retrospective clinical data were collected from medical records and interviews. We identified 19 cases in 13 Swedish families. A JLNS prevalence >1:200 000 was revealed (five living cases <10 years of age). The mutation spectrum consisted of eight KCNQ1 mutations, whereof p.R518X in 12/24 alleles. Geographic clustering of four mutations (20/24 alleles) and similarities to Norway's mutation spectrum were seen. A high prevalence of heterozygotes was suggested. Three paediatric cases on β-blockers since birth were as yet asymptomatic. Seven symptomatic cases had suffered an aborted cardiac arrest and four had died suddenly. QTc prolongation was significantly longer in symptomatic cases (mean 605 ± 62 vs. 518 ± 50 ms, P = 0.016). β-Blockers reduced, but did not abolish, cardiac events in any previously symptomatic case. β-Blocker type, dosage, and compliance probably affect outcome significantly. Implantable cardioverter-defibrillator therapy (ICD, n = 6) was associated with certain complications; however, no case of sudden death. CONCLUSION Founder effects could explain 83% of the Swedish JLNS mutation spectrum and probably contribute to the high JLNS prevalence found in preadolescent Swedish children. Due to the severe cardiac phenotype in JLNS, the importance of stringent β-blocker therapy and compliance, and consideration of ICD implantation in the case of therapy failure is stressed.
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Affiliation(s)
- Annika Winbo
- Division of Pediatrics, Department of Clinical Sciences, Pediatrics, Umeå University, 90185 Umeå, Sweden.
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Readthrough of long-QT syndrome type 1 nonsense mutations rescues function but alters the biophysical properties of the channel. Biochem J 2012; 443:635-42. [DOI: 10.1042/bj20111912] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The nonsense mutations R518X-KCNQ1 and Q530X-KCNQ1 cause LQT1 (long-QT syndrome type 1) and result in a complete loss of IKs channel function. In the present study we attempted to rescue the function of these mutants, in HEK (human embryonic kidney)-293 cells, by promoting readthrough of their PTCs (premature termination codons) using the pharmacological agents G-418, gentamicin and PTC124. Gentamicin and G-418 acted to promote full-length channel protein expression from R518X at 100 μM and from Q530X at 1 mM. In contrast, PTC124 did not, at any dose tested, induce readthrough of either mutant. G-418 (1 mM) treatment also acted to significantly (P<0.05) increase current density and peak-tail current density, at +80 mV for R518X, but not Q530X, to 58±11% and 82±17% of the wild-type level respectively. However, the biophysical properties of the currents produced from R518X, while similar, were not identical with wild-type as the voltage-dependence of activation was significantly (P<0.05) shifted by +25 mV. Overall, these findings indicate that although functional rescue of LQT1 nonsense mutations is possible, it is dependent on the degree of readthrough achieved and the effect on channel function of the amino acid substituted for the PTC. Such considerations will determine the success of future therapies.
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Mahboubi H, Dwabe S, Fradkin M, Kimonis V, Djalilian HR. Genetics of hearing loss: where are we standing now? Eur Arch Otorhinolaryngol 2012; 269:1733-45. [PMID: 22218850 DOI: 10.1007/s00405-011-1910-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 12/27/2011] [Indexed: 01/23/2023]
Abstract
Hearing loss (HL) is the most common sensory impairment and is caused by a broad range of inherited to environmental causes. Inherited HL consists 50-60% of all HL cases. The inherited form of HL is further classified to different categories. More than 300 syndromes and 40 genes have been identified to result in different levels of HL. Although several diagnostic or screening tests have been developed, yet there are controversies around their use.
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Affiliation(s)
- Hossein Mahboubi
- Department of Otolaryngology Head and Neck Surgery, University of California, Irvine, 101 The City Drive South, Bldg 56, Suite 500, Rt 81, Orange, CA 92868, USA
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Amin AS, Giudicessi JR, Tijsen AJ, Spanjaart AM, Reckman YJ, Klemens CA, Tanck MW, Kapplinger JD, Hofman N, Sinner MF, Müller M, Wijnen WJ, Tan HL, Bezzina CR, Creemers EE, Wilde AAM, Ackerman MJ, Pinto YM. Variants in the 3' untranslated region of the KCNQ1-encoded Kv7.1 potassium channel modify disease severity in patients with type 1 long QT syndrome in an allele-specific manner. Eur Heart J 2011; 33:714-23. [PMID: 22199116 PMCID: PMC3303714 DOI: 10.1093/eurheartj/ehr473] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Aims Heterozygous mutations in KCNQ1 cause type 1 long QT syndrome (LQT1), a disease characterized by prolonged heart rate-corrected QT interval (QTc) and life-threatening arrhythmias. It is unknown why disease penetrance and expressivity is so variable between individuals hosting identical mutations. We aimed to study whether this can be explained by single nucleotide polymorphisms (SNPs) in KCNQ1's 3′ untranslated region (3′UTR). Methods and results This study was performed in 84 LQT1 patients from the Academic Medical Center in Amsterdam and validated in 84 LQT1 patients from the Mayo Clinic in Rochester. All patients were genotyped for SNPs in KCNQ1's 3′UTR, and six SNPs were found. Single nucleotide polymorphisms rs2519184, rs8234, and rs10798 were associated in an allele-specific manner with QTc and symptom occurrence. Patients with the derived SNP variants on their mutated KCNQ1 allele had shorter QTc and fewer symptoms, while the opposite was also true: patients with the derived SNP variants on their normal KCNQ1 allele had significantly longer QTc and more symptoms. Luciferase reporter assays showed that the expression of KCNQ1's 3′UTR with the derived SNP variants was lower than the expression of the 3′UTR with the ancestral SNP variants. Conclusion Our data indicate that 3′UTR SNPs potently modify disease severity in LQT1. The allele-specific effects of the SNPs on disease severity and gene expression strongly suggest that they are functional variants that directly alter the expression of the allele on which they reside, and thereby influence the balance between proteins stemming from either the normal or the mutant KCNQ1 allele.
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Affiliation(s)
- Ahmad S Amin
- Heart Failure Research Center, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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The voltage-gated channel accessory protein KCNE2: multiple ion channel partners, multiple ways to long QT syndrome. Expert Rev Mol Med 2011; 13:e38. [DOI: 10.1017/s1462399411002092] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The single-pass transmembrane protein KCNE2 or MIRP1 was once thought to be the missing accessory protein that combined with hERG to fully recapitulate the cardiac repolarising current IKr. As a result of this role, it was an easy next step to associate mutations in KCNE2 to long QT syndrome, in which there is delayed repolarisation of the heart. Since that time however, KCNE2 has been shown to modify the behaviour of several other channels and currents, and its role in the heart and in the aetiology of long QT syndrome has become less clear. In this article, we review the known interactions of the KCNE2 protein and the resulting functional effects, and the effects of mutations in KCNE2 and their clinical role.
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Roberts JD, Gollob MH. The genetic and clinical features of cardiac channelopathies. Future Cardiol 2010; 6:491-506. [PMID: 20608822 DOI: 10.2217/fca.10.27] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Sudden cardiac death, secondary to malignant ventricular arrhythmias, has traditionally been associated with structural heart disease. An important exception includes a group of clinical entities referred to as 'channelopathies' that develop secondary to genetic mutations, which alter cardiac ion channel activity. Otherwise healthy individuals affected by these forms of primary electrical disease are vulnerable to fatal arrhythmic events from a very young age. At present, there are four distinct conditions that are classified as cardiac channelopathies, namely congenital long-QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia and short-QT syndrome. Our growing insight into the genetics of these conditions has led to an improved understanding of the molecular pathophysiology responsible for the malignant arrhythmias characterizing these disorders. However, despite our knowledge of these conditions, the success of medical therapy remains modest and the prevention of sudden cardiac death may necessitate insertion of an implantable cardioverter-defibrillator. The young age of affected patients makes this a particularly undesirable treatment strategy and emphasizes the importance of translating our insight into the molecular pathophysiology defining these conditions into more effective forms of therapy.
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Affiliation(s)
- Jason D Roberts
- Arrhythmia Research Laboratory, University of Ottawa Heart Institute, 40 Ruskin Street, Ottawa, ON K1Y 4W7, Canada
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A new homozygous mutation of the KCNQ1 gene associated with both Romano-Ward and incomplete Jervell Lange-Nielsen syndromes in two sisters. Heart Rhythm 2010; 7:531-3. [DOI: 10.1016/j.hrthm.2009.11.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 11/30/2009] [Indexed: 01/16/2023]
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Clinical and genetic analysis of long QT syndrome in children from six families in Saudi Arabia: are they different? Pediatr Cardiol 2009; 30:490-501. [PMID: 19184172 DOI: 10.1007/s00246-008-9377-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 11/13/2008] [Accepted: 12/24/2008] [Indexed: 10/21/2022]
Abstract
Congenital long QT syndrome (LQTS) is an inherited cardiac arrhythmia disorder characterized by prolongation of the QT interval; patients are predisposed to ventricular tachyarrhythmias and fibrillation leading to recurrent syncope or sudden cardiac death. We performed clinical and genetic studies in six Saudi Arabian families with a history of sudden unexplained death of children. Clinical symptoms, ECG phenotypes, and genetic findings led to the diagnosis of LQT1 in two families (recessive) and LQT2 in four families (three recessive and one dominant). Onset of arrhythmia was more severe in the recessive carriers and occurred during early childhood in all recessive LQT1 patients. Arrhythmia originated at the intrauterine stages of life in the recessive LQT2 patients. LQT1, causing mutation c.387-5 T > A in the KCNQ1 gene, and LQT2, causing mutation c.3208 C > T in the KCNH2 gene, are presumably founder mutations in the Assir province of Saudi Arabia. Further, all LQTS causing mutations detected in this study are novel and have not been reported in other populations.
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Prothero KE, Stahl JM, Carrel L. Dosage compensation and gene expression on the mammalian X chromosome: one plus one does not always equal two. Chromosome Res 2009; 17:637-48. [PMID: 19802704 PMCID: PMC4941101 DOI: 10.1007/s10577-009-9063-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Counting chromosomes is not just simple math. Although normal males and females differ in sex chromosome content (XY vs. XX), X chromosome imbalance is tolerated because dosage compensation mechanisms have evolved to ensure functional equivalence. In mammals this is accomplished by two processes--X chromosome inactivation that silences most genes on one X chromosome in females, leading to functional X monosomy for most genes in both sexes, and X chromosome upregulation that results in increased gene expression on the single active X in males and females, equalizing dosage relative to autosomes. This review focuses on genes on the X chromosome, and how gene content, organization and expression levels can be influenced by these two processes. Special attention is given to genes that are not X inactivated, and are not necessarily fully dosage compensated. These genes that "escape" X inactivation are of medical importance as they explain phenotypes in individuals with sex chromosome aneuploidies and may impact normal traits and disorders that differ between men and women. Moreover, escape genes give insight into how X chromosome inactivation is spread and maintained on the X.
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Affiliation(s)
- Katie E. Prothero
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Jill M. Stahl
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Laura Carrel
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
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