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Maslen CL. Human Genetics of Atrioventricular Septal Defect. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1441:559-571. [PMID: 38884732 DOI: 10.1007/978-3-031-44087-8_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Atrioventricular septal defects (AVSD), also known as a common atrioventricular canal (CAVC), are clinically severe heart malformations that affect about 1 out of every 2100 live births. AVSD makes up about 5% of all congenital heart defects. AVSD is associated with cytogenetic disorders such as Down syndrome and numerous other rare genetic syndromes, but also occurs as a simplex trait. Studies in mouse models have identified over 100 genetic mutations that have the potential to cause an AVSD. However, studies in humans indicate that AVSD is genetically heterogeneous, and that the cause in humans is very rarely a single-gene defect. Familial cases do occur albeit rarely, usually with autosomal dominant inheritance and variable expression. In addition, the frequent occurrence of AVSD in some syndromes with known genetic causes such as heterotaxy syndrome points to additional genes/pathways that increase AVSD risk. Accordingly, while the genetic underpinnings for most AVSD remain unknown, there have been advances in identifying genetic risk factors for AVSD in both syndromic and nonsyndromic cases. This chapter summarizes the current knowledge of the genetic basis for AVSD.
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Affiliation(s)
- Cheryl L Maslen
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, USA.
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Hu Y, Jin L, Wang Z. Genome-wide association study of dilated cardiomyopathy-induced heart failure associated with renal insufficiency in a Chinese population. BMC Cardiovasc Disord 2023; 23:335. [PMID: 37391705 PMCID: PMC10314512 DOI: 10.1186/s12872-023-03370-0] [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: 10/20/2022] [Accepted: 06/28/2023] [Indexed: 07/02/2023] Open
Abstract
BACKGROUND As it is unclear whether there is genetic susceptibility to cardiorenal syndrome (CRS), we conducted a genome-wide association study of dilated cardiomyopathy (DCM)-induced heart failure (HF) associated with renal insufficiency (RI) in a Chinese population to identify putative susceptibility variants and culprit genes. METHODS A total of 99 Han Chinese patients with DCM-induced chronic HF were selected and divided into one of three groups, namely, HF with normal renal function (Group 1), HF with mild RI (Group 2) and HF with moderate to severe RI (Group 3). Genomic DNA was extracted from each subject for genotyping. RESULTS According to Gene Ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, top 10 lists of molecular function, cell composition and biological process of differential target genes and 15 signalling pathways were discriminated among the three groups. Additionally, sequencing results identified 26 significantly different single-nucleotide polymorphisms (SNPs) in the 15 signalling pathways, including three SNPs (rs57938337, rs6683225 and rs6692782) in ryanodine receptor 2 (RYR2) and two SNPs (rs12439006 and rs16958069) in RYR3. The genotype and allele frequencies of the five SNPs in RYR2 and RYR3 were significantly differential between HF (Group 1) and CRS (Group 2 + 3) patients. CONCLUSION Twenty-six significantly different SNP loci in 17 genes of the 15 KEGG pathways were found in the three patient groups. Among these variants, rs57938337, rs6683225 and rs6692782 in RYR2 and rs12439006 and rs16958069 in RYR3 are associated with RI in Han Chinese patients with heart failure, suggesting that these variants may be used to identify patients susceptible to CRS in the future.
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Affiliation(s)
- Yuexin Hu
- Department of Cardiovascular Medicine, Affiliated Nanjing Brain Hospital, Nanjing Medical University, No. 246 Guangzhou Road, Nanjing, Jiangsu, 210008, China
- Department of Cardiovascular Medicine, Nanjing Chest Hospital, Nanjing, China
| | - Liangli Jin
- Department of Cardiovascular Medicine, Affiliated Nanjing Brain Hospital, Nanjing Medical University, No. 246 Guangzhou Road, Nanjing, Jiangsu, 210008, China
- Department of Cardiovascular Medicine, Nanjing Chest Hospital, Nanjing, China
| | - Zhi Wang
- Department of Cardiovascular Medicine, Affiliated Nanjing Brain Hospital, Nanjing Medical University, No. 246 Guangzhou Road, Nanjing, Jiangsu, 210008, China.
- Department of Cardiovascular Medicine, Nanjing Chest Hospital, Nanjing, China.
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Bolunduț AC, Lazea C, Mihu CM. Genetic Alterations of Transcription Factors and Signaling Molecules Involved in the Development of Congenital Heart Defects-A Narrative Review. CHILDREN (BASEL, SWITZERLAND) 2023; 10:children10050812. [PMID: 37238360 DOI: 10.3390/children10050812] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/23/2023] [Accepted: 04/27/2023] [Indexed: 05/28/2023]
Abstract
Congenital heart defects (CHD) are the most common congenital abnormality, with an overall global birth prevalence of 9.41 per 1000 live births. The etiology of CHDs is complex and still poorly understood. Environmental factors account for about 10% of all cases, while the rest are likely explained by a genetic component that is still under intense research. Transcription factors and signaling molecules are promising candidates for studies regarding the genetic burden of CHDs. The present narrative review provides an overview of the current knowledge regarding some of the genetic mechanisms involved in the embryological development of the cardiovascular system. In addition, we reviewed the association between the genetic variation in transcription factors and signaling molecules involved in heart development, including TBX5, GATA4, NKX2-5 and CRELD1, and congenital heart defects, providing insight into the complex pathogenesis of this heterogeneous group of diseases. Further research is needed in order to uncover their downstream targets and the complex network of interactions with non-genetic risk factors for a better molecular-phenotype correlation.
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Affiliation(s)
- Alexandru Cristian Bolunduț
- 1st Department of Pediatrics, "Iuliu Hațieganu" University of Medicine and Pharmacy, 400370 Cluj-Napoca, Romania
| | - Cecilia Lazea
- 1st Department of Pediatrics, "Iuliu Hațieganu" University of Medicine and Pharmacy, 400370 Cluj-Napoca, Romania
- 1st Pediatrics Clinic, Emergency Pediatric Hospital, 400370 Cluj-Napoca, Romania
| | - Carmen Mihaela Mihu
- Department of Histology, "Iuliu Hațieganu" University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
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Beckert V, Rassmann S, Kayvanjoo AH, Klausen C, Bonaguro L, Botermann DS, Krause M, Moreth K, Spielmann N, da Silva-Buttkus P, Fuchs H, Gailus-Durner V, de Angelis MH, Händler K, Ulas T, Aschenbrenner AC, Mass E, Wachten D. Creld1 regulates myocardial development and function. J Mol Cell Cardiol 2021; 156:45-56. [PMID: 33773996 DOI: 10.1016/j.yjmcc.2021.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 02/25/2021] [Accepted: 03/18/2021] [Indexed: 12/14/2022]
Abstract
CRELD1 (Cysteine-Rich with EGF-Like Domains 1) is a risk gene for non-syndromic atrioventricular septal defects in human patients. In a mouse model, Creld1 has been shown to be essential for heart development, particularly in septum and valve formation. However, due to the embryonic lethality of global Creld1 knockout (KO) mice, its cell type-specific function during peri- and postnatal stages remains unknown. Here, we generated conditional Creld1 KO mice lacking Creld1 either in the endocardium (KOTie2) or the myocardium (KOMyHC). Using a combination of cardiac phenotyping, histology, immunohistochemistry, RNA-sequencing, and flow cytometry, we demonstrate that Creld1 function in the endocardium is dispensable for heart development. Lack of myocardial Creld1 causes extracellular matrix remodeling and trabeculation defects by modulation of the Notch1 signaling pathway. Hence, KOMyHC mice die early postnatally due to myocardial hypoplasia. Our results reveal that Creld1 not only controls the formation of septa and valves at an early stage during heart development, but also cardiac maturation and function at a later stage. These findings underline the central role of Creld1 in mammalian heart development and function.
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Affiliation(s)
- Vera Beckert
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Sebastian Rassmann
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Amir Hossein Kayvanjoo
- Life & Medical Institute (LIMES), Developmental Biology of the Immune System, University of Bonn, 53115 Bonn, Germany
| | - Christina Klausen
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Lorenzo Bonaguro
- Life & Medical Institute (LIMES), Genomics and Immunoregulation, University of Bonn, 53115 Bonn, Germany
| | - Dominik Simon Botermann
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Melanie Krause
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, 53127 Bonn, Germany
| | - Kristin Moreth
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Nadine Spielmann
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Patricia da Silva-Buttkus
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Martin Hrabě de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Chair of Experimental Genetics, School of Life Science Weihenstephan, Technical University Munich, 85354 Freising, Germany; German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany
| | - Kristian Händler
- German Center for Neurodegenerative Diseases (DZNE), PRECISE Platform for Single Cell Genomics and Epigenomics at the DZNE and the University of Bonn, 53127 Bonn, Germany
| | - Thomas Ulas
- Life & Medical Institute (LIMES), Genomics and Immunoregulation, University of Bonn, 53115 Bonn, Germany; German Center for Neurodegenerative Diseases (DZNE), PRECISE Platform for Single Cell Genomics and Epigenomics at the DZNE and the University of Bonn, 53127 Bonn, Germany
| | - Anna C Aschenbrenner
- Life & Medical Institute (LIMES), Genomics and Immunoregulation, University of Bonn, 53115 Bonn, Germany; Department of Internal Medicine and Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, 6500HB Nijmegen, the Netherlands
| | - Elvira Mass
- Life & Medical Institute (LIMES), Developmental Biology of the Immune System, University of Bonn, 53115 Bonn, Germany.
| | - Dagmar Wachten
- Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
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Gholipoorfeshkecheh R, Agarwala S, G K, Krishnappa S, Savitha MR, Ramachandra NB. Whole-exome sequencing and homozygosity mapping identify variants in NCOR1 and MAP2K3 associated with non-syndromic congenital heart defects. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2020. [DOI: 10.1186/s43042-020-00101-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Homozygosity mapping is an efficient gene mapping method applicable to recessive disorders. It can detect homozygous segments of identical haplotype structures shared at a higher frequency among ventricular septal defect (VSD) and tetralogy of Fallot (TOF) cases. This study aims to identify the recessive genes involved in congenital heart disease (CHD) cases by homozygosity mapping. A total of 36 CHD cases of Indian origin were recruited based on inclusion and exclusion criteria, disease severity, and hole size. Of these, ten prediagnosed VSD and TOF cases were selected for homozygosity mapping. For in silico validation of variations, overlapping gene variants were analyzed from 26 cases based on pathogenecity and haploinsufficiency scores.
Results
Genome-wide homozygosity mapping identified 34 homozygous regions with a maximum block length of 80 bp marked for the CHD samples under study. A total of 4863 genes were identified in these 34 homozygous regions, which were present across almost all chromosomes except chromosomes 4, 8, 12, and 13. The homozygosity region found in chromosome 17 revealed genes for CHD manifestation. This homozygous region contained VSD- and TOF-related genes—Nuclear Corepressor 1 (NCOR1) and Mitogen-Activated Protein Kinase Kinase 3 (MAP2K3). In silico validation identified damaging variants for NCOR1 and MAP2K3. Three variants, G207C, C241T, and G244A, were found on exon 2 in the transcript NM_001190438 for NCOR1. Three variants were also found for MAP2K3, namely G194T and C199T in exon 5 and C578T in exon 8 in the transcript NM_002756. All these variants were present in the protein kinase domain.
Conclusion
Presence of homozygous regions identifies recessive genes leading to disease severity. Defects in recessive genes NCOR1 and MAP2K3 are responsible for abnormal myogenesis, resulting in CHD manifestation.
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Asim A, Agarwal S, Panigrahi I, Sarangi AN, Muthuswamy S, Kapoor A. CRELD1 gene variants and atrioventricular septal defects in Down syndrome. Gene 2018; 641:180-185. [DOI: 10.1016/j.gene.2017.10.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 09/21/2017] [Accepted: 10/16/2017] [Indexed: 10/18/2022]
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Guo C, Wang Q, Wang Y, Yang L, Luo H, Cao XF, An L, Qiu Y, Du M, Ma X, Li H, Lu C. Exome sequencing reveals novel IRXI mutation in congenital heart disease. Mol Med Rep 2017; 15:3193-3197. [DOI: 10.3892/mmr.2017.6410] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/19/2017] [Indexed: 11/06/2022] Open
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Zhang K, Song F, Zhang D, Liu Y, Zhang H, Wang Y, Dong R, Zhang Y, Liu Y, Gai Z. Chromosome r(3)(p25.3q29) in a Patient with Developmental Delay and Congenital Heart Defects: A Case Report and a Brief Literature Review. Cytogenet Genome Res 2016; 148:6-13. [PMID: 27077748 DOI: 10.1159/000445273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Indexed: 11/19/2022] Open
Abstract
Ring chromosome 3, r(3), is an extremely rare cytogenetic abnormality with clinical heterogeneity and only 12 cases reported in the literature. Here, we report a 1-year-old girl presenting distinctive facial features, developmental delay, and congenital heart defects with r(3) and a ∼10-Mb deletion of chromosome 3pterp25.3 (61,891-9,979,408) involving 42 known genes which was detected using G-banding karyotyping and CytoScan 750K-Array. The breakpoints in r(3) were mapped at 3p25.3 and 3q29. We also analyzed the available information on the clinical features of the reported cases with r(3) and 3p deletion syndrome in order to provide more valuable information of genotype-phenotype correlations. To our knowledge, this is the largest detected fragment described in r(3) cases and the second r(3) study using whole-genome microarray.
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Affiliation(s)
- Kaihui Zhang
- Pediatric Research Institute, Qilu Children's Hospital of Shandong University, Jinan, China
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Ackerman C, Locke A, Feingold E, Reshey B, Espana K, Thusberg J, Mooney S, Bean L, Dooley K, Cua C, Reeves R, Sherman S, Maslen C. An excess of deleterious variants in VEGF-A pathway genes in Down-syndrome-associated atrioventricular septal defects. Am J Hum Genet 2012; 91:646-59. [PMID: 23040494 PMCID: PMC3484504 DOI: 10.1016/j.ajhg.2012.08.017] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 06/12/2012] [Accepted: 08/17/2012] [Indexed: 12/20/2022] Open
Abstract
About half of people with trisomy 21 have a congenital heart defect (CHD), whereas the remainder have a structurally normal heart, demonstrating that trisomy 21 is a significant risk factor but is not causal for abnormal heart development. Atrioventricular septal defects (AVSD) are the most commonly occurring heart defects in Down syndrome (DS), and ∼65% of all AVSD is associated with DS. We used a candidate-gene approach among individuals with DS and complete AVSD (cases = 141) and DS with no CHD (controls = 141) to determine whether rare genetic variants in genes involved in atrioventricular valvuloseptal morphogenesis contribute to AVSD in this sensitized population. We found a significant excess (p < 0.0001) of variants predicted to be deleterious in cases compared to controls. At the most stringent level of filtering, we found potentially damaging variants in nearly 20% of cases but fewer than 3% of controls. The variants with the highest probability of being damaging in cases only were found in six genes: COL6A1, COL6A2, CRELD1, FBLN2, FRZB, and GATA5. Several of the case-specific variants were recurrent in unrelated individuals, occurring in 10% of cases studied. No variants with an equal probability of being damaging were found in controls, demonstrating a highly specific association with AVSD. Of note, all of these genes are in the VEGF-A pathway, even though the candidate genes analyzed in this study represented numerous biochemical and developmental pathways, suggesting that rare variants in the VEGF-A pathway might contribute to the genetic underpinnings of AVSD in humans.
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Affiliation(s)
- Christine Ackerman
- Division of Cardiovascular Medicine and the Heart Research Center, Oregon Health & Science University, Portland, OR 97239, USA
| | - Adam E. Locke
- Department of Human Genetics, Emory University, Atlanta, GA 30033, USA
| | - Eleanor Feingold
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Benjamin Reshey
- Division of Cardiovascular Medicine and the Heart Research Center, Oregon Health & Science University, Portland, OR 97239, USA
| | - Karina Espana
- Division of Cardiovascular Medicine and the Heart Research Center, Oregon Health & Science University, Portland, OR 97239, USA
| | | | - Sean Mooney
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Lora J.H. Bean
- Department of Human Genetics, Emory University, Atlanta, GA 30033, USA
| | - Kenneth J. Dooley
- Sibley Heart Center Cardiology and Division of Pediatric Cardiology, Children’s Healthcare of Atlanta, Department of Pediatrics, Emory University, Atlanta, GA 30033, USA
| | - Clifford L. Cua
- Heart Center, Nationwide Children’s Hospital, Columbus, OH 43205, USA
| | - Roger H. Reeves
- Department of Physiology and the Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | - Cheryl L. Maslen
- Division of Cardiovascular Medicine and the Heart Research Center, Oregon Health & Science University, Portland, OR 97239, USA
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Ghosh P, Bhaumik P, Ghosh S, Ozbek U, Feingold E, Maslen C, Sarkar B, Pramanik V, Biswas P, Bandyopadhyay B, Dey SK. Polymorphic haplotypes of CRELD1 differentially predispose Down syndrome and euploids individuals to atrioventricular septal defect. Am J Med Genet A 2012; 158A:2843-8. [PMID: 22987595 DOI: 10.1002/ajmg.a.35626] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 07/26/2012] [Indexed: 11/05/2022]
Abstract
To explore the role of CRELD1 variants on congenital heart defects, we sequenced the entire reading frame of CRELD1 in the samples from Kolkata and adjoining areas. Nearly, 400 participants were included in the genetic association study and they were stratified as Down syndrome (DS) with atrioventricular septal defect (AVSD), DS without AVSD, euploid with AVSD, and euploid without AVSD. A significant association was found between AVSD and three polymorphisms, namely rs9878047 (c.1049-129T > C), rs3774207 (c.1119C > T), and rs73118372 (c.1136T > C) among the Down syndrome and euploid individuals. The polymorphism rs73118372, involves a transition (c.1136T > C) that leads to change in amino acid methionine to threonine which alters protein secondary structure as confirmed by the bioinformatics software SOPMA. In addition, two haplotypes, C-T-C and C-T-T, in the order of loci rs9878047-rs3774207-rs73118372 were associated with incidence of AVSD among euploid and Down syndrome, with a slightly higher odds ratio in the later group. We hypothesize that these haplotypes increase the risk of AVSD, and the susceptibility is exacerbated in DS, possibly due to the trisomy 21 genetic background. Moreover, we report for the first time on an interaction between the mutant alleles of rs3774207 and rs73118372 which could disrupt the delicate balance between different CRELD1 isoforms.
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Affiliation(s)
- Priyanka Ghosh
- Human Genetics Research Unit, School of Biotechnology and Biological Sciences, West Bengal University of Technology, Kolkata, West Bengal, India
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Zhian S, Belmont J, Maslen CL. Specific association of missense mutations in CRELD1 with cardiac atrioventricular septal defects in heterotaxy syndrome. Am J Med Genet A 2012; 158A:2047-9. [PMID: 22740159 DOI: 10.1002/ajmg.a.35457] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 04/12/2012] [Indexed: 11/10/2022]
Affiliation(s)
- Samaneh Zhian
- Department of Biology, Portland State University, Portland, Oregon 97034, USA
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12
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Li H, Cherry S, Klinedinst D, DeLeon V, Redig J, Reshey B, Chin MT, Sherman SL, Maslen CL, Reeves RH. Genetic modifiers predisposing to congenital heart disease in the sensitized Down syndrome population. ACTA ACUST UNITED AC 2012; 5:301-8. [PMID: 22523272 DOI: 10.1161/circgenetics.111.960872] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND About half of people with Down syndrome (DS) exhibit some form of congenital heart disease (CHD); however, trisomy for human chromosome 21 (Hsa21) alone is insufficient to cause CHD, as half of all people with DS have a normal heart, suggesting that genetic modifiers interact with dosage-sensitive gene(s) on Hsa21 to result in CHD. We hypothesize that a threshold exists in both DS and euploid populations for the number of genetic perturbations that can be tolerated before CHD results. METHODS AND RESULTS We ascertained a group of individuals with DS and complete atrioventricular septal defect and sequenced 2 candidate genes for CHD: CRELD1, which is associated with atrioventricular septal defect in people with or without DS, and HEY2, whose mouse ortholog (Hey2) produces septal defects when mutated. Several deleterious variants were identified, but the frequency of these potential modifiers was low. We crossed mice with mutant forms of these potential modifiers to the Ts65Dn mouse model of DS. Crossing loss-of-function alleles of either Creld1 or Hey2 onto the trisomic background caused a significant increase in the frequency of CHD, demonstrating an interaction between the modifiers and trisomic genes. We showed further that, although each of these mutant modifiers is benign by itself, they interact to affect heart development when inherited together. CONCLUSIONS Using mouse models of Down syndrome and of genes associated with congenital heart disease, we demonstrate a biological basis for an interaction that supports a threshold hypothesis for additive effects of genetic modifiers in the sensitized trisomic population.
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Affiliation(s)
- Huiqing Li
- Department of Physiology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
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