1
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Farris J, Khanna C, Smadbeck JB, Johnson SH, Bothun E, Kaplan T, Hoffman F, Polonis K, Oliver G, Reis LM, Semina EV, Rust L, Hoppman NL, Vasmatzis G, Marcou CA, Schimmenti LA, Klee EW. Complex balanced intrachromosomal rearrangement involving PITX2 identified as a cause of Axenfeld-Rieger Syndrome. Am J Med Genet A 2024; 194:e63542. [PMID: 38234180 PMCID: PMC11003841 DOI: 10.1002/ajmg.a.63542] [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: 08/28/2023] [Revised: 12/15/2023] [Accepted: 01/07/2024] [Indexed: 01/19/2024]
Abstract
Axenfeld-Rieger Syndrome (ARS) type 1 is a rare autosomal dominant condition characterized by anterior chamber anomalies, umbilical defects, dental hypoplasia, and craniofacial anomalies, with Meckel's diverticulum in some individuals. Here, we describe a clinically ascertained female of childbearing age with ARS for whom clinical targeted sequencing and deletion/duplication analysis followed by clinical exome and genome sequencing resulted in no pathogenic variants or variants of unknown significance in PITX2 or FOXC1. Advanced bioinformatic analysis of the genome data identified a complex, balanced rearrangement disrupting PITX2. This case is the first reported intrachromosomal rearrangement leading to ARS, illustrating that for patients with compelling clinical phenotypes but negative genomic testing, additional bioinformatic analysis are essential to identify subtle genomic abnormalities in target genes.
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Affiliation(s)
- Joseph Farris
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Cheryl Khanna
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
| | - James B Smadbeck
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Sarah H Johnson
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Erick Bothun
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
| | - Tyler Kaplan
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA
| | - Francis Hoffman
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Katarzyna Polonis
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Gavin Oliver
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Wisconsin, Milwaukee, Wisconsin, USA
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Wisconsin, Milwaukee, Wisconsin, USA
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Laura Rust
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota, USA
| | - Nicole L Hoppman
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - George Vasmatzis
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, USA
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota, USA
| | - Cherisse A Marcou
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Lisa A Schimmenti
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota, USA
| | - Eric W Klee
- Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota, USA
- Department of Quantitative Health Sciences, Mayo Clinic, Rochester, Minnesota, USA
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2
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Jiang Y, Peng Y, Tian Q, Cheng Z, Feng B, Hu J, Xia L, Guo H, Xia K, Zhou L, Hu Z. Intergenic sequences harboring potential enhancer elements contribute to Axenfeld-Rieger syndrome by regulating PITX2. JCI Insight 2024; 9:e177032. [PMID: 38592784 PMCID: PMC11141933 DOI: 10.1172/jci.insight.177032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 03/27/2024] [Indexed: 04/11/2024] Open
Abstract
Recent studies have uncovered that noncoding sequence variants may relate to Axenfeld-Rieger syndrome (ARS), a rare developmental anomaly with genetic heterogeneity. However, how these genomic regions are functionally and structurally associated with ARS is still unclear. In this study, we performed genome-wide linkage analysis and whole-genome sequencing in a Chinese family with ARS and identified a heterozygous deletion of about 570 kb (termed LOH-1) in the intergenic sequence between paired-like homeodomain transcription factor 2 (PITX2) and family with sequence similarity 241 member A. Knockout of LOH-1 homologous sequences caused ARS phenotypes in mice. RNA-Seq and real-time quantitative PCR revealed a significant reduction in Pitx2 gene expression in LOH-1-/- mice, while forkhead box C1 expression remained unchanged. ChIP-Seq and bioinformatics analysis identified a potential enhancer region (LOH-E1) within LOH-1. Deletion of LOH-E1 led to a substantial downregulation of the PITX2 gene. Mechanistically, we found a sequence (hg38 chr4:111,399,594-111,399,691) that is on LOH-E1 could regulate PITX2 by binding to RAD21, a critical component of the cohesin complex. Knockdown of RAD21 resulted in reduced PITX2 expression. Collectively, our findings indicate that a potential enhancer sequence that is within LOH-1 may regulate PITX2 expression remotely through cohesin-mediated loop domains, leading to ARS when absent.
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Affiliation(s)
- Yizheng Jiang
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
| | - Yu Peng
- Department of Medical Genetics, The Affiliated Children’s Hospital of Xiangya School of Medicine, Central South University, Changsha, China
| | - Qi Tian
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
| | - Zhe Cheng
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
| | - Bei Feng
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
| | - Junping Hu
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
| | - Lu Xia
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
| | - Hui Guo
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
| | - Kun Xia
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
- MOE Key Laboratory of Rare Pediatric Diseases, Hengyang Medical School, University of South China, Hengyang, China
| | - Liang Zhou
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Zhengmao Hu
- MOE Key Laboratory of Rare Pediatric Diseases & Hunan Key Laboratory of Medical Genetics of the School of Life Sciences and
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3
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Cheng YHH, Bohaczuk SC, Stergachis AB. Functional categorization of gene regulatory variants that cause Mendelian conditions. Hum Genet 2024; 143:559-605. [PMID: 38436667 PMCID: PMC11078748 DOI: 10.1007/s00439-023-02639-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 12/30/2023] [Indexed: 03/05/2024]
Abstract
Much of our current understanding of rare human diseases is driven by coding genetic variants. However, non-coding genetic variants play a pivotal role in numerous rare human diseases, resulting in diverse functional impacts ranging from altered gene regulation, splicing, and/or transcript stability. With the increasing use of genome sequencing in clinical practice, it is paramount to have a clear framework for understanding how non-coding genetic variants cause disease. To this end, we have synthesized the literature on hundreds of non-coding genetic variants that cause rare Mendelian conditions via the disruption of gene regulatory patterns and propose a functional classification system. Specifically, we have adapted the functional classification framework used for coding variants (i.e., loss-of-function, gain-of-function, and dominant-negative) to account for features unique to non-coding gene regulatory variants. We identify that non-coding gene regulatory variants can be split into three distinct categories by functional impact: (1) non-modular loss-of-expression (LOE) variants; (2) modular loss-of-expression (mLOE) variants; and (3) gain-of-ectopic-expression (GOE) variants. Whereas LOE variants have a direct corollary with coding loss-of-function variants, mLOE and GOE variants represent disease mechanisms that are largely unique to non-coding variants. These functional classifications aim to provide a unified terminology for categorizing the functional impact of non-coding variants that disrupt gene regulatory patterns in Mendelian conditions.
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Affiliation(s)
- Y H Hank Cheng
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Stephanie C Bohaczuk
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Andrew B Stergachis
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA.
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA.
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4
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Reis LM, Maheshwari M, Capasso J, Atilla H, Dudakova L, Thompson S, Zitano L, Lay-Son G, Lowry RB, Black J, Lee J, Shue A, Kremlikova Pourova R, Vaneckova M, Skalicka P, Jedlickova J, Trkova M, Williams B, Richard G, Bachman K, Seeley AH, Costakos D, Glaser TM, Levin AV, Liskova P, Murray JC, Semina EV. Axenfeld-Rieger syndrome: more than meets the eye. J Med Genet 2023; 60:368-379. [PMID: 35882526 PMCID: PMC9912354 DOI: 10.1136/jmg-2022-108646] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/15/2022] [Indexed: 12/11/2022]
Abstract
BACKGROUND Axenfeld-Rieger syndrome (ARS) is characterised by typical anterior segment anomalies, with or without systemic features. The discovery of causative genes identified ARS subtypes with distinct phenotypes, but our understanding is incomplete, complicated by the rarity of the condition. METHODS Genetic and phenotypic characterisation of the largest reported ARS cohort through comprehensive genetic and clinical data analyses. RESULTS 128 individuals with causative variants in PITX2 or FOXC1, including 81 new cases, were investigated. Ocular anomalies showed significant overlap but with broader variability and earlier onset of glaucoma for FOXC1-related ARS. Systemic anomalies were seen in all individuals with PITX2-related ARS and the majority of those with FOXC1-related ARS. PITX2-related ARS demonstrated typical umbilical anomalies and dental microdontia/hypodontia/oligodontia, along with a novel high rate of Meckel diverticulum. FOXC1-related ARS exhibited characteristic hearing loss and congenital heart defects as well as previously unrecognised phenotypes of dental enamel hypoplasia and/or crowding, a range of skeletal and joint anomalies, hypotonia/early delay and feeding disorders with structural oesophageal anomalies in some. Brain imaging revealed highly penetrant white matter hyperintensities, colpocephaly/ventriculomegaly and frequent arachnoid cysts. The expanded phenotype of FOXC1-related ARS identified here was found to fully overlap features of De Hauwere syndrome. The results were used to generate gene-specific management plans for the two types of ARS. CONCLUSION Since clinical features of ARS vary significantly based on the affected gene, it is critical that families are provided with a gene-specific diagnosis, PITX2-related ARS or FOXC1-related ARS. De Hauwere syndrome is proposed to be a FOXC1opathy.
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Affiliation(s)
- Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Wisconsin, Milwaukee, Wisconsin, USA
| | - Mohit Maheshwari
- Department of Pediatric Radiology, Medical College of Wisconsin and Children's Wisconsin, Milwaukee, Wisconsin, USA
| | - Jenina Capasso
- Pediatric Ophthalmology and Ocular Genetics, Flaum Eye Institute, Golisano Children's Hospital and University of Rochester, Rochester, New York, USA
| | - Huban Atilla
- Department of Ophthalmology, School of Medicine, Ankara University, Ankara, Turkey
| | - Lubica Dudakova
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Samuel Thompson
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Wisconsin, Milwaukee, Wisconsin, USA
| | - Lia Zitano
- Department of Medical Genetics, Spectrum Health, Grand Rapids, Michigan, USA
| | - Guillermo Lay-Son
- Unidad de Genética, División de Pediatría, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - R Brian Lowry
- Department of Clinical Genetics, Alberta Children's Hospital, Calgary, Alberta, Canada
| | - Jennifer Black
- Center for Development, Behavior, and Genetics, SUNY Upstate Medical University, Syracuse, New York, USA
| | - Joseph Lee
- Department of Family Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Ann Shue
- Byers Eye Institute, Department of Ophthalmology, Stanford University and Stanford Children's Health, Stanford, California, USA
| | - Radka Kremlikova Pourova
- Department of Biology and Medical Genetics, Second Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Manuela Vaneckova
- Department of Radiology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Pavlina Skalicka
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
- Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Jana Jedlickova
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Marie Trkova
- Gennet, Centre for Fetal Medicine and Reproductive Genetics, Prague, Czech Republic
| | | | | | - Kristine Bachman
- Department of Pediatrics, Geisinger Medical Center, Danville, Pennsylvania, USA
| | - Andrea H Seeley
- Department of Pediatrics, Geisinger Medical Center, Danville, Pennsylvania, USA
| | - Deborah Costakos
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Thomas M Glaser
- Department of Cell Biology and Human Anatomy, UC-Davis School of Medicine, Davis, California, USA
| | - Alex V Levin
- Pediatric Ophthalmology and Ocular Genetics, Flaum Eye Institute, Golisano Children's Hospital and University of Rochester, Rochester, New York, USA
| | - Petra Liskova
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Jeffrey C Murray
- Department of Pediatrics, University of Iowa, Iowa City, Iowa, USA
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Wisconsin, Milwaukee, Wisconsin, USA
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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5
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Ferre-Fernández JJ, Muheisen S, Thompson S, Semina EV. CRISPR-Cas9-mediated functional dissection of the foxc1 genomic region in zebrafish identifies critical conserved cis-regulatory elements. Hum Genomics 2022; 16:49. [PMID: 36284357 PMCID: PMC9597995 DOI: 10.1186/s40246-022-00423-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 10/19/2022] [Indexed: 11/10/2022] Open
Abstract
FOXC1 encodes a forkhead-domain transcription factor associated with several ocular disorders. Correct FOXC1 dosage is critical to normal development, yet the mechanisms controlling its expression remain unknown. Together with FOXQ1 and FOXF2, FOXC1 is part of a cluster of FOX genes conserved in vertebrates. CRISPR-Cas9-mediated dissection of genomic sequences surrounding two zebrafish orthologs of FOXC1 was performed. This included five zebrafish-human conserved regions, three downstream of foxc1a and two remotely upstream of foxf2a/foxc1a or foxf2b/foxc1b clusters, as well as two intergenic regions between foxc1a/b and foxf2a/b lacking sequence conservation but positionally corresponding to the area encompassing a previously reported glaucoma-associated SNP in humans. Removal of downstream sequences altered foxc1a expression; moreover, zebrafish carrying deletions of two or three downstream elements demonstrated abnormal phenotypes including enlargement of the anterior chamber of the eye reminiscent of human congenital glaucoma. Deletions of distant upstream conserved elements influenced the expression of foxf2a/b or foxq1a/b but not foxc1a/b within each cluster. Removal of either intergenic sequence reduced foxc1a or foxc1b expression during late development, suggesting a role in transcriptional regulation despite the lack of conservation at the nucleotide level. Further studies of the identified regions in human patients may explain additional individuals with developmental ocular disorders.
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Affiliation(s)
- Jesús-José Ferre-Fernández
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, 53226, USA
| | - Sanaa Muheisen
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, 53226, USA
| | - Samuel Thompson
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, 53226, USA
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, 53226, USA.
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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6
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Zigova M, Petrejèíková E, Blašèáková M, Kmec J, Bernasovská J, Boroòová I, Kmec M. Genetic targets in the management of atrial fibrillation in patients with cardiomyopathy. JOURNAL OF THE PRACTICE OF CARDIOVASCULAR SCIENCES 2022. [DOI: 10.4103/jpcs.jpcs_65_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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7
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French CR. Mechanistic Insights into Axenfeld-Rieger Syndrome from Zebrafish foxc1 and pitx2 Mutants. Int J Mol Sci 2021; 22:ijms221810001. [PMID: 34576164 PMCID: PMC8472202 DOI: 10.3390/ijms221810001] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/03/2021] [Accepted: 09/05/2021] [Indexed: 12/11/2022] Open
Abstract
Axenfeld-Rieger syndrome (ARS) encompasses a group of developmental disorders that affect the anterior segment of the eye, as well as systemic developmental defects in some patients. Malformation of the ocular anterior segment often leads to secondary glaucoma, while some patients also present with cardiovascular malformations, craniofacial and dental abnormalities and additional periumbilical skin. Genes that encode two transcription factors, FOXC1 and PITX2, account for almost half of known cases, while the genetic lesions in the remaining cases remain unresolved. Given the genetic similarity between zebrafish and humans, as well as robust antisense inhibition and gene editing technologies available for use in these animals, loss of function zebrafish models for ARS have been created and shed light on the mechanism(s) whereby mutations in these two transcription factors cause such a wide array of developmental phenotypes. This review summarizes the published phenotypes in zebrafish foxc1 and pitx2 loss of function models and discusses possible mechanisms that may be used to target pharmaceutical development and therapeutic interventions.
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Affiliation(s)
- Curtis R French
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland and Labrador, St. John's, NL A1B 3V6, Canada
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8
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Geoffroy V, Guignard T, Kress A, Gaillard JB, Solli-Nowlan T, Schalk A, Gatinois V, Dollfus H, Scheidecker S, Muller J. AnnotSV and knotAnnotSV: a web server for human structural variations annotations, ranking and analysis. Nucleic Acids Res 2021; 49:W21-W28. [PMID: 34023905 PMCID: PMC8262758 DOI: 10.1093/nar/gkab402] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/16/2021] [Accepted: 04/29/2021] [Indexed: 11/13/2022] Open
Abstract
With the dramatic increase of pangenomic analysis, Human geneticists have generated large amount of genomic data including millions of small variants (SNV/indel) but also thousands of structural variations (SV) mainly from next-generation sequencing and array-based techniques. While the identification of the complete SV repertoire of a patient is getting possible, the interpretation of each SV remains challenging. To help identifying human pathogenic SV, we have developed a web server dedicated to their annotation and ranking (AnnotSV) as well as their visualization and interpretation (knotAnnotSV) freely available at the following address: https://www.lbgi.fr/AnnotSV/. A large amount of annotations from >20 sources is integrated in our web server including among others genes, haploinsufficiency, triplosensitivity, regulatory elements, known pathogenic or benign genomic regions, phenotypic data. An ACMG/ClinGen compliant prioritization module allows the scoring and the ranking of SV into 5 SV classes from pathogenic to benign. Finally, the visualization interface displays the annotated SV in an interactive way including popups, search fields, filtering options, advanced colouring to highlight pathogenic SV and hyperlinks to the UCSC genome browser or other public databases. This web server is designed for diagnostic and research analysis by providing important resources to the user.
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Affiliation(s)
- Véronique Geoffroy
- Laboratoire de Génétique Médicale, U1112, INSERM, IGMA, FMTS, Université de Strasbourg, Strasbourg, France
| | | | - Arnaud Kress
- Complex Systems and Translational Bioinformatics, ICube, UMR 7357, University of Strasbourg, CNRS, FMTS, Strasbourg, France
| | | | - Tor Solli-Nowlan
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Audrey Schalk
- Laboratoires de Diagnostic Génétique, IGMA, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | | | - Hélène Dollfus
- Laboratoire de Génétique Médicale, U1112, INSERM, IGMA, FMTS, Université de Strasbourg, Strasbourg, France
- Centre de référence pour les Affections Rares en Génétique Ophtalmologique, Filière SENSGENE, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Sophie Scheidecker
- Laboratoire de Génétique Médicale, U1112, INSERM, IGMA, FMTS, Université de Strasbourg, Strasbourg, France
- Laboratoires de Diagnostic Génétique, IGMA, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Jean Muller
- Laboratoire de Génétique Médicale, U1112, INSERM, IGMA, FMTS, Université de Strasbourg, Strasbourg, France
- Laboratoires de Diagnostic Génétique, IGMA, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
- Unité Fonctionnelle de Bioinformatique Médicale appliquée au diagnostic (UF7363), Hôpitaux Universitaires de Strasbourg, Strasbourg, France
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9
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Walter MA, Rezaie T, Hufnagel RB, Arno G. Ocular genetics in the genomics age. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:860-868. [PMID: 32896097 DOI: 10.1002/ajmg.c.31844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 12/29/2022]
Abstract
Current genetic screening methods for inherited eye diseases are concentrated on the coding exons of known disease genes (gene panels, clinical exome). These tests have a variable and often limited diagnostic rate depending on the clinical presentation, size of the gene panel and our understanding of the inheritance of the disorder (with examples described in this issue). There are numerous possible explanations for the missing heritability of these cases including undetected variants within the relevant gene (intronic, up/down-stream and structural variants), variants harbored in genes outside the targeted panel, intergenic variants, variants undetectable by the applied technology, complex/non-Mendelian inheritance, and nongenetic phenocopies. In this article we further explore and review methods to investigate these sources of missing heritability.
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Affiliation(s)
- Michael A Walter
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Tayebeh Rezaie
- National Center for Biotechnology Information, National Institutes of Health, Bethesda, Maryland, USA
| | - Robert B Hufnagel
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Gavin Arno
- University College London Institute of Ophthalmology, London, UK.,Moorfields Eye Hospital, London, UK
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10
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Yoon KH, Fox SC, Dicipulo R, Lehmann OJ, Waskiewicz AJ. Ocular coloboma: Genetic variants reveal a dynamic model of eye development. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:590-610. [PMID: 32852110 DOI: 10.1002/ajmg.c.31831] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 12/21/2022]
Abstract
Ocular coloboma is a congenital disorder of the eye where a gap exists in the inferior retina, lens, iris, or optic nerve tissue. With a prevalence of 2-19 per 100,000 live births, coloboma, and microphthalmia, an associated ocular disorder, represent up to 10% of childhood blindness. It manifests due to the failure of choroid fissure closure during eye development, and it is a part of a spectrum of ocular disorders that include microphthalmia and anophthalmia. Use of genetic approaches from classical pedigree analyses to next generation sequencing has identified more than 40 loci that are associated with the causality of ocular coloboma. As we have expanded studies to include singleton cases, hereditability has been very challenging to prove. As such, researchers over the past 20 years, have unraveled the complex interrelationship amongst these 40 genes using vertebrate model organisms. Such research has greatly increased our understanding of eye development. These genes function to regulate initial specification of the eye field, migration of retinal precursors, patterning of the retina, neural crest cell biology, and activity of head mesoderm. This review will discuss the discovery of loci using patient data, their investigations in animal models, and the recent advances stemming from animal models that shed new light in patient diagnosis.
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Affiliation(s)
- Kevin H Yoon
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
| | - Sabrina C Fox
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
| | - Renée Dicipulo
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
| | - Ordan J Lehmann
- Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada.,Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.,Department of Ophthalmology, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew J Waskiewicz
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, University of Alberta, Edmonton, Canada
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11
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Van Der Meulen KL, Vöcking O, Weaver ML, Meshram NN, Famulski JK. Spatiotemporal Characterization of Anterior Segment Mesenchyme Heterogeneity During Zebrafish Ocular Anterior Segment Development. Front Cell Dev Biol 2020; 8:379. [PMID: 32528955 PMCID: PMC7266958 DOI: 10.3389/fcell.2020.00379] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/27/2020] [Indexed: 12/20/2022] Open
Abstract
Assembly of the ocular anterior segment (AS) is a critical event during development of the vertebrate visual system. Failure in this process leads to anterior segment dysgenesis (ASD), which is characterized by congenital blindness and predisposition to glaucoma. The anterior segment is largely formed via a neural crest-derived population, the Periocular Mesenchyme (POM). In this study, we aimed to characterize POM behaviors and transcriptional identities during early establishment of the zebrafish AS. Two-color fluorescent in situ hybridization suggested that early AS associated POM comprise of a heterogenous population. In vivo and time-course imaging analysis of POM distribution and migratory dynamics analyzed using transgenic zebrafish embryos (Tg[foxc1b:GFP], Tg[foxd3:GFP], Tg[pitx2:GFP], Tg[lmx1b.1:GFP], and Tg[sox10:GFP]) revealed unique AS distribution and migratory behavior among the reporter lines. Based on fixed timepoint and real-time analysis of POM cell behavior a comprehensive model for colonization of the zebrafish AS was assembled. Furthermore, we generated single cell transcriptomic profiles (scRNA) from our POM reporter lines and characterized unique subpopulation expression patterns. Based on scRNA clustering analysis we observed cluster overlap between neural crest associated (sox10/foxd3), POM (pitx2) and finally AS specified cells (lmx1b, and foxc1b). scRNA clustering also revealed several novel markers potentially associated with AS development and/or function including lum, fmoda, adcyap1b, tgfbi, and hmng2. Taken together, our data indicates that AS-associated POM, or Anterior Segment Mesenchyme (ASM), is not homogeneous but rather comprised of several subpopulations with differing colonization patterns, migration behavior, and transcriptomic profiles.
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Affiliation(s)
| | - Oliver Vöcking
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - Megan L Weaver
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - Nishita N Meshram
- Department of Biology, University of Kentucky, Lexington, KY, United States
| | - Jakub K Famulski
- Department of Biology, University of Kentucky, Lexington, KY, United States
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Orlova E, Carlson JC, Lee MK, Feingold E, McNeil DW, Crout RJ, Weyant RJ, Marazita ML, Shaffer JR. Pilot GWAS of caries in African-Americans shows genetic heterogeneity. BMC Oral Health 2019; 19:215. [PMID: 31533690 PMCID: PMC6751797 DOI: 10.1186/s12903-019-0904-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 08/30/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Dental caries is the most common chronic disease in the US and disproportionately affects racial/ethnic minorities. Caries is heritable, and though genetic heterogeneity exists between ancestries for a substantial portion of loci associated with complex disease, a genome-wide association study (GWAS) of caries specifically in African Americans has not been performed previously. METHODS We performed exploratory GWAS of dental caries in 109 African American adults (age > 18) and 96 children (age 3-12) from the Center for Oral Health Research in Appalachia (COHRA1 cohort). Caries phenotypes (DMFS, DMFT, dft, and dfs indices) assessed by dental exams were tested for association with 5 million genotyped or imputed single nucleotide polymorphisms (SNPs), separately in the two age groups. The GWAS was performed using linear regression with adjustment for age, sex, and two principal components of ancestry. A maximum of 1 million adaptive permutations were run to determine empirical significance. RESULTS No loci met the threshold for genome-wide significance, though some of the strongest signals were near genes previously implicated in caries such as antimicrobial peptide DEFB1 (rs2515501; p = 4.54 × 10- 6) and TUFT1 (rs11805632; p = 5.15 × 10- 6). Effect estimates of lead SNPs at suggestive loci were compared between African Americans and Caucasians (adults N = 918; children N = 983). Significant (p < 5 × 10- 8) genetic heterogeneity for caries risk was found between racial groups for 50% of the suggestive loci in children, and 12-18% of the suggestive loci in adults. CONCLUSIONS The genetic heterogeneity results suggest that there may be differences in the contributions of genetic variants to caries across racial groups, and highlight the critical need for the inclusion of minorities in subsequent and larger genetic studies of caries in order to meet the goals of precision medicine and to reduce oral health disparities.
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Affiliation(s)
- E Orlova
- Department of Human Genetics, Pittsburgh, USA
| | - J C Carlson
- Department of Biostatistics, Graduate School of Public Health, Pittsburgh, USA
| | - M K Lee
- Center for Craniofacial and Dental Genetics, Dept. of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - E Feingold
- Department of Human Genetics, Pittsburgh, USA
- Department of Biostatistics, Graduate School of Public Health, Pittsburgh, USA
- Center for Craniofacial and Dental Genetics, Dept. of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - D W McNeil
- Departments of Psychology, & Dental Practice and Rural Health, West Virginia University, Morgantown, USA
| | - R J Crout
- Department of Periodontics, School of Dentistry, West Virginia University, Morgantown, WV, USA
| | - R J Weyant
- Department of Dental Public Health and Information Management, Pittsburgh, USA
| | - M L Marazita
- Department of Human Genetics, Pittsburgh, USA
- Center for Craniofacial and Dental Genetics, Dept. of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Clinical and Translational Sciences Institute, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - J R Shaffer
- Department of Human Genetics, Pittsburgh, USA.
- Center for Craniofacial and Dental Genetics, Dept. of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
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Karnuta JM, Scacheri PC. Enhancers: bridging the gap between gene control and human disease. Hum Mol Genet 2019; 27:R219-R227. [PMID: 29726898 DOI: 10.1093/hmg/ddy167] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 05/02/2018] [Indexed: 01/21/2023] Open
Abstract
Enhancers are a class of regulatory elements essential for precise spatio-temporal control of gene expression during development and in terminally differentiated cells. This review highlights signature features of enhancer elements as well as new advances that provide mechanistic insights into enhancer-mediated gene control in the context of three-dimensional chromatin. We detail the various ways in which non-coding mutations can instigate aberrant gene control and cause a variety of Mendelian disorders, common diseases and cancer.
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Affiliation(s)
- Jaret M Karnuta
- Department of Genetics and Genome Sciences, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA.,Cleveland Clinic Lerner College of Medicine, Cleveland, OH, USA
| | - Peter C Scacheri
- Department of Genetics and Genome Sciences, Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA
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14
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Genetics of anophthalmia and microphthalmia. Part 1: Non-syndromic anophthalmia/microphthalmia. Hum Genet 2019; 138:799-830. [PMID: 30762128 DOI: 10.1007/s00439-019-01977-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/30/2019] [Indexed: 12/22/2022]
Abstract
Eye formation is the result of coordinated induction and differentiation processes during embryogenesis. Disruption of any one of these events has the potential to cause ocular growth and structural defects, such as anophthalmia and microphthalmia (A/M). A/M can be isolated or occur with systemic anomalies, when they may form part of a recognizable syndrome. Their etiology includes genetic and environmental factors; several hundred genes involved in ocular development have been identified in humans or animal models. In humans, around 30 genes have been repeatedly implicated in A/M families, although many other genes have been described in single cases or families, and some genetic syndromes include eye anomalies occasionally as part of a wider phenotype. As a result of this broad genetic heterogeneity, with one or two notable exceptions, each gene explains only a small percentage of cases. Given the overlapping phenotypes, these genes can be most efficiently tested on panels or by whole exome/genome sequencing for the purposes of molecular diagnosis. However, despite whole exome/genome testing more than half of patients currently remain without a molecular diagnosis. The proportion of undiagnosed cases is even higher in those individuals with unilateral or milder phenotypes. Furthermore, even when a strong gene candidate is available for a patient, issues of incomplete penetrance and germinal mosaicism make diagnosis and genetic counseling challenging. In this review, we present the main genes implicated in non-syndromic human A/M phenotypes and, for practical purposes, classify them according to the most frequent or predominant phenotype each is associated with. Our intention is that this will allow clinicians to rank and prioritize their molecular analyses and interpretations according to the phenotypes of their patients.
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Wang X, Liu X, Huang L, Fang S, Jia X, Xiao X, Li S, Guo X. Mutation Survey of Candidate Genes and Genotype-Phenotype Analysis in 20 Southeastern Chinese Patients with Axenfeld-Rieger Syndrome. Curr Eye Res 2018; 43:1334-1341. [PMID: 29939776 DOI: 10.1080/02713683.2018.1493129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 10/28/2022]
Abstract
Purpose/aim of the study: To conduct a survey spectrum of the PITX2, FOXC1, and PRDM5 genes to reveal genotype-phenotype correlations in a cohort of Southeastern Chinese patients with Axenfeld-Rieger syndrome (ARS). MATERIALS AND METHODS A total of 20 probands with ARS were recruited in Southeast China. All patients underwent full ocular and systemic examinations. Sanger sequencing was used to analyze all coding regions of and regions adjacent to PITX2, FOXC1, and PRDM5 and 13 upstream regulatory elements of PITX2. Multiplex ligation-dependent probe amplification was performed to detect gross insertions and deletions in PITX2 and FOXC1. Quantitative polymerase chain reaction was used to detect copy number variations in regulatory elements of PITX2. A bioinformatics analysis was conducted to evaluate the pathogenicity of variants. RESULTS Eleven mutations, including eight novel mutations, were identified in PITX2. Seven of the mutations were truncations. A genotype-phenotype correlation analysis showed that 81.8% (9/11) of patients with mutations in PITX2 developed glaucoma before reaching 10 years old. The proportion of patients without detected mutations was only 33.3% (3/9, P = 0.0399). In patient G1399, ultrasound biomicroscopy revealed that the left eye exhibited a phenotype similar to aniridia with complete angle closure and a remaining stub of iris tissue. CONCLUSION This is the first genetic study of a cohort of Southeastern Chinese patients with ARS. Eight novel mutations were detected, expanding the mutation spectrum of PITX2. PITX2 may be a major candidate gene for ARS in Southeastern Chinese patients. Truncations may be the primary mutation type in PITX2. Glaucoma onset may be earlier in patients with mutations in PITX2 than in those without mutations in PITX2 and FOXC1. A block of the anterior chamber angle by the end of the iris might represent the main factor influencing the development of glaucoma in ARS patients with an asymmetric aniridia phenotype.
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Affiliation(s)
- Xun Wang
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
| | - Xing Liu
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
| | - Liqin Huang
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
| | - Shaohua Fang
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
| | - Xiaoyun Jia
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
| | - Xueshan Xiao
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
| | - Shiqiang Li
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
| | - Xiangming Guo
- a State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center , Sun Yat-Sen University , Guangzhou , China
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Hendee KE, Sorokina EA, Muheisen SS, Reis LM, Tyler RC, Markovic V, Cuturilo G, Link BA, Semina EV. PITX2 deficiency and associated human disease: insights from the zebrafish model. Hum Mol Genet 2018; 27:1675-1695. [PMID: 29506241 PMCID: PMC5932568 DOI: 10.1093/hmg/ddy074] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 01/30/2018] [Accepted: 02/26/2018] [Indexed: 02/06/2023] Open
Abstract
The PITX2 (paired-like homeodomain 2) gene encodes a bicoid-like homeodomain transcription factor linked with several human disorders. The main associated congenital phenotype is Axenfeld-Rieger syndrome, type 1, an autosomal dominant condition characterized by variable defects in the anterior segment of the eye, an increased risk of glaucoma, craniofacial dysmorphism and dental and umbilical anomalies; in addition to this, one report implicated PITX2 in ring dermoid of the cornea and a few others described cardiac phenotypes. We report three novel PITX2 mutations-c.271C > T, p.(Arg91Trp); c.259T > C, p.(Phe87Leu); and c.356delA, p.(Gln119Argfs*36)-identified in independent families with typical Axenfeld-Rieger syndrome characteristics and some unusual features such as corneal guttata, Wolf-Parkinson-White syndrome, and hyperextensibility. To gain further insight into the diverse roles of PITX2/pitx2 in vertebrate development, we generated various genetic lesions in the pitx2 gene via TALEN-mediated genome editing. Affected homozygous zebrafish demonstrated congenital defects consistent with the range of PITX2-associated human phenotypes: abnormal development of the cornea, iris and iridocorneal angle; corneal dermoids; and craniofacial dysmorphism. In addition, via comparison of pitx2M64* and wild-type embryonic ocular transcriptomes we defined molecular changes associated with pitx2 deficiency, thereby implicating processes potentially underlying disease pathology. This analysis identified numerous affected factors including several members of the Wnt pathway and collagen types I and V gene families. These data further support the link between PITX2 and the WNT pathway and suggest a new role in regulation of collagen gene expression during development.
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Affiliation(s)
- Kathryn E Hendee
- Department of Pediatrics and Children’s Research Institute Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI 53226, USA
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Elena A Sorokina
- Department of Pediatrics and Children’s Research Institute Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI 53226, USA
| | - Sanaa S Muheisen
- Department of Pediatrics and Children’s Research Institute Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI 53226, USA
| | - Linda M Reis
- Department of Pediatrics and Children’s Research Institute Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI 53226, USA
| | - Rebecca C Tyler
- Department of Pediatrics and Children’s Research Institute Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI 53226, USA
| | - Vujica Markovic
- Faculty of Medicine, University of Belgrade, Serbia
- Clinical Centre of Serbia, University Eye Hospital, Belgrade, Serbia
| | - Goran Cuturilo
- Faculty of Medicine, University of Belgrade, Serbia
- Department of Medical Genetics, University Children’s Hospital, Belgrade, Serbia
| | - Brian A Link
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Elena V Semina
- Department of Pediatrics and Children’s Research Institute Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI 53226, USA
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Akula M, Park JW, West-Mays JA. Relationship between neural crest cell specification and rare ocular diseases. J Neurosci Res 2018; 97:7-15. [PMID: 29660784 DOI: 10.1002/jnr.24245] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/15/2018] [Accepted: 03/21/2018] [Indexed: 02/06/2023]
Abstract
Development of the eye is closely associated with neural crest cell migration and specification. Eye development is extremely complex, as it requires the working of a combination of local factors, receptors, inductors, and signaling interactions between tissues such as the optic cup and periocular mesenchyme (POM). The POM is comprised of neural crest-derived mesenchymal progenitor cells that give rise to numerous important ocular structures including those tissues that form the optic cup and anterior segment of the eye. A number of genes are involved in the migration and specification of the POM such as PITX2, PITX3, FOXC1, FOXE3, PAX6, LMX1B, GPR48, TFAP2A, and TFAP2B. In this review, we will discuss the relevance of these genes in the development of the POM and how mutations and defects result in rare ocular diseases.
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Affiliation(s)
- Monica Akula
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Jeong Won Park
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Judith A West-Mays
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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18
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Seifi M, Walter MA. Axenfeld-Rieger syndrome. Clin Genet 2018; 93:1123-1130. [PMID: 28972279 DOI: 10.1111/cge.13148] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 09/23/2017] [Accepted: 09/26/2017] [Indexed: 12/29/2022]
Abstract
Axenfeld-Rieger syndrome (ARS) is a clinically and genetically heterogeneous group of developmental disorders affecting primarily the anterior segment of the eye, often leading to secondary glaucoma. Patients with ARS may also present with systemic changes, including dental defects, mild craniofacial dysmorphism, and umbilical anomalies. ARS is inherited in an autosomal-dominant fashion; the underlying defect in 40% of patients is mutations in PITX2 or FOXC1. Here, an overview of the clinical spectrum of ARS is provided. As well, the known underlying genetic defects, clinical diagnostic possibilities, genetic counseling and treatments of ARS are discussed in detail.
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Affiliation(s)
- M Seifi
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Edmonton, Canada
| | - M A Walter
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Edmonton, Canada
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Protas ME, Weh E, Footz T, Kasberger J, Baraban SC, Levin AV, Katz LJ, Ritch R, Walter MA, Semina EV, Gould DB. Mutations of conserved non-coding elements of PITX2 in patients with ocular dysgenesis and developmental glaucoma. Hum Mol Genet 2017; 26:3630-3638. [PMID: 28911203 PMCID: PMC5886142 DOI: 10.1093/hmg/ddx251] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/09/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
Mutations in FOXC1 and PITX2 constitute the most common causes of ocular anterior segment dysgenesis (ASD), and confer a high risk for secondary glaucoma. The genetic causes underlying ASD in approximately half of patients remain unknown, despite many of them being screened by whole exome sequencing. Here, we performed whole genome sequencing on DNA from two affected individuals from a family with dominantly inherited ASD and glaucoma to identify a 748-kb deletion in a gene desert that contains conserved putative PITX2 regulatory elements. We used CRISPR/Cas9 to delete the orthologous region in zebrafish in order to test the pathogenicity of this structural variant. Deletion in zebrafish reduced pitx2 expression during development and resulted in shallow anterior chambers. We screened additional patients for copy number variation of the putative regulatory elements and found an overlapping deletion in a second family and in a potentially-ancestrally-related index patient with ASD and glaucoma. These data suggest that mutations affecting conserved non-coding elements of PITX2 may constitute an important class of mutations in patients with ASD for whom the molecular cause of their disease have not yet been identified. Improved functional annotation of the human genome and transition to sequencing of patient genomes instead of exomes will be required before the magnitude of this class of mutations is fully understood.
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Affiliation(s)
- Meredith E. Protas
- Departments of Ophthalmology and Anatomy and Institute for Human Genetics, University of California, San Francisco, CA 94143, USA
| | - Eric Weh
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Tim Footz
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Jay Kasberger
- Celgene Quanticel Research, San Francisco, CA 94158, USA
| | - Scott C. Baraban
- Department of Neurological Surgery, University of California, San Francisco, CA 94143, USA
| | - Alex V. Levin
- Pediatric Ophthalmology and Ocular Genetics, Wills Eye Hospital, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - L. Jay Katz
- Glaucoma Service, Wills Eye Hospital, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Robert Ritch
- Einhorn Clinical Research Center, The New York Eye and Ear Infirmary of Mount Sinai, New York, NY 10003, USA
| | - Michael A. Walter
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Elena V. Semina
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Douglas B. Gould
- Departments of Ophthalmology and Anatomy and Institute for Human Genetics, University of California, San Francisco, CA 94143, USA
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Seifi M, Footz T, Taylor SAM, Elhady GM, Abdalla EM, Walter MA. Novel PITX2 gene mutations in patients with Axenfeld-Rieger syndrome. Acta Ophthalmol 2016; 94:e571-e579. [PMID: 27009473 DOI: 10.1111/aos.13030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 01/23/2016] [Indexed: 02/06/2023]
Abstract
PURPOSE Mutations in the bicoid-like transcription factor PITX2 gene often result in Axenfeld-Rieger syndrome (ARS), an autosomal-dominant inherited disorder. We report here the discovery and characterization of novel PITX2 deletions in a small kindred with ARS. METHODS Two familial patients (father and son) from a consanguineous family were examined in the present study. Patient DNA samples were screened for PITX2 mutations by DNA sequencing and for copy number variation by SYBR Green quantitative polymerase chain reaction (PCR) analysis. RESULTS We report a novel deletion involving the coding region of PITX2 in both patients. The minimum size of the deletion is 1 421 914 bp that spans one upstream regulatory element (CE4), PITX2 and a minimum of 13 neighbouring genes. The maximum size of the deletion is 3 789 983 bp. The proband (son) additionally possesses a novel 2-bp deletion in a non-coding exon of the remaining PITX2 allele predicted to alter correct splicing. CONCLUSION Our findings implicate a novel deletion of the PITX2 gene in the pathogenesis of ARS in the affected family. This ARS family presented with an atypical and extremely severe phenotype that resulted in four miscarriages and the death at 10 months of age of a sib of the proband. As the phenotypic manifestations in the proband are more severe than that of the father, we hypothesize that the deletion of the entire PITX2 allele plus a novel 2-bp deletion (observed in the proband) within the remaining PITX2 allele together contributed to the atypical ARS presentation in this family. This is the first study reporting on bi-allelic changes of PITX2 potentially contributing to a more severe ARS phenotype.
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Affiliation(s)
- Morteza Seifi
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Tim Footz
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Sherry A M Taylor
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Ghada M Elhady
- Department of Human Genetics, Medical Research Institute, Alexandria University, Alexandria, Egypt
| | - Ebtesam M Abdalla
- Department of Human Genetics, Medical Research Institute, Alexandria University, Alexandria, Egypt
| | - Michael A Walter
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.
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Happ H, Weh E, Costakos D, Reis LM, Semina EV. Case report of homozygous deletion involving the first coding exons of GCNT2 isoforms A and B and part of the upstream region of TFAP2A in congenital cataract. BMC MEDICAL GENETICS 2016; 17:64. [PMID: 27609212 PMCID: PMC5016880 DOI: 10.1186/s12881-016-0316-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 07/28/2016] [Indexed: 12/14/2022]
Abstract
BACKGROUND Congenital cataracts affect 3-6 per 10,000 live births and represent one of the leading causes of blindness in children. Congenital cataracts have a strong genetic component with high heterogeneity and variability. CASE PRESENTATION Analysis of whole exome sequencing data in a patient affected with congenital cataracts identified a pathogenic deletion which was further defined by other techniques. A ~98-kb homozygous deletion of 6p24.3 involving the first three exons (two non-coding and one coding) of GCNT2 isoform A, the first exon (coding) of GCNT2 isoform B, and part of the intergenic region between GCNT2 and TFAP2A was identified in the patient and her brother while both parents were found to be heterozygous carriers of the deletion. The exact breakpoints were identified and revealed the presence of Alu elements at both sides of the deletion, thus indicating Alu-mediated non-homologous end-joining as the most plausible mechanism for this rearrangement. Recessive mutations in GCNT2 are known to cause an adult i blood group phenotype with congenital cataracts in some cases. The GCNT2 gene has three differentially expressed transcripts, with GCNT2B being the only isoform associated with lens function and GCNT2C being the only isoform expressed in red blood cells based on earlier studies; previously reported mutations/deletions have either affected all three isoforms (causing blood group and cataract phenotype) or the C isoform only (causing blood group phenotype only). Dominant mutations in TFAP2A are associated with syndromic anophthalmia/microphthalmia and other ocular phenotypes as part of Branchio-Ocular-Facial-Syndrome (BOFS). While the patients do not fit a diagnosis of BOFS, one sibling demonstrates mild overlap with the phenotypic spectrum, and therefore an effect of this deletion on the function of TFAP2A cannot be ruled out. CONCLUSIONS To the best of our knowledge, this is the first case reported in which disruption of the GCNT2 gene does not involve the C isoform. The congenital cataracts phenotype in the affected patients is consistent with the previously defined isoform-specific roles of this gene. The GCNT2-TFAP2A region may be prone to rearrangements through Alu-mediated non-homologous end-joining.
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Affiliation(s)
- Hannah Happ
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Eric Weh
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Deborah Costakos
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA. .,Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA. .,Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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Ansari M, Rainger J, Hanson IM, Williamson KA, Sharkey F, Harewood L, Sandilands A, Clayton-Smith J, Dollfus H, Bitoun P, Meire F, Fantes J, Franco B, Lorenz B, Taylor DS, Stewart F, Willoughby CE, McEntagart M, Khaw PT, Clericuzio C, Van Maldergem L, Williams D, Newbury-Ecob R, Traboulsi EI, Silva ED, Madlom MM, Goudie DR, Fleck BW, Wieczorek D, Kohlhase J, McTrusty AD, Gardiner C, Yale C, Moore AT, Russell-Eggitt I, Islam L, Lees M, Beales PL, Tuft SJ, Solano JB, Splitt M, Hertz JM, Prescott TE, Shears DJ, Nischal KK, Doco-Fenzy M, Prieur F, Temple IK, Lachlan KL, Damante G, Morrison DA, van Heyningen V, FitzPatrick DR. Genetic Analysis of 'PAX6-Negative' Individuals with Aniridia or Gillespie Syndrome. PLoS One 2016; 11:e0153757. [PMID: 27124303 PMCID: PMC4849793 DOI: 10.1371/journal.pone.0153757] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 04/04/2016] [Indexed: 12/26/2022] Open
Abstract
We report molecular genetic analysis of 42 affected individuals referred with a diagnosis of aniridia who previously screened as negative for intragenic PAX6 mutations. Of these 42, the diagnoses were 31 individuals with aniridia and 11 individuals referred with a diagnosis of Gillespie syndrome (iris hypoplasia, ataxia and mild to moderate developmental delay). Array-based comparative genomic hybridization identified six whole gene deletions: four encompassing PAX6 and two encompassing FOXC1. Six deletions with plausible cis-regulatory effects were identified: five that were 3' (telomeric) to PAX6 and one within a gene desert 5' (telomeric) to PITX2. Sequence analysis of the FOXC1 and PITX2 coding regions identified two plausibly pathogenic de novo FOXC1 missense mutations (p.Pro79Thr and p.Leu101Pro). No intragenic mutations were detected in PITX2. FISH mapping in an individual with Gillespie-like syndrome with an apparently balanced X;11 reciprocal translocation revealed disruption of a gene at each breakpoint: ARHGAP6 on the X chromosome and PHF21A on chromosome 11. In the other individuals with Gillespie syndrome no mutations were identified in either of these genes, or in HCCS which lies close to the Xp breakpoint. Disruption of PHF21A has previously been implicated in the causation of intellectual disability (but not aniridia). Plausibly causative mutations were identified in 15 out of 42 individuals (12/32 aniridia; 3/11 Gillespie syndrome). Fourteen of these mutations presented in the known aniridia genes; PAX6, FOXC1 and PITX2. The large number of individuals in the cohort with no mutation identified suggests greater locus heterogeneity may exist in both isolated and syndromic aniridia than was previously appreciated.
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Affiliation(s)
- Morad Ansari
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Jacqueline Rainger
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Isabel M. Hanson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Kathleen A. Williamson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Freddie Sharkey
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Louise Harewood
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Angela Sandilands
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Jill Clayton-Smith
- Faculty of Medical and Human Sciences, Manchester Centre for Genomic Medicine, Institute of Human Development, University of Manchester, Manchester Academic Health Science Centre (MAHSC), Manchester, United Kingdom
| | - Helene Dollfus
- Service de Génétique Médicale, Hôpital de Haute-Pierre, Strasbourg, France
| | - Pierre Bitoun
- Medical Genetics Departments, University Hospital Jean Verdier, Bondy, France
| | - Francoise Meire
- Department of ophthalmopediatrics, Hôpital Universitaire des Enfants Reine Fabiola, Bruxelles, Belgium
| | - Judy Fantes
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Brunella Franco
- Medical Genetics, Department of Medical Translational Sciences, Federico II University, Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Birgit Lorenz
- Department of Ophthalmology, Justus-Liebig-University Giessen, Universitaetsklinikum Giessen and Marburg UKGM, Giessen, Germany
| | - David S. Taylor
- Institute of Child Health, University College London, UK and Great Ormond Street Hospital for Children, London, United Kingdom
| | - Fiona Stewart
- Northern Ireland Regional Genetics Service (NIRGS), Belfast City Hospital, Belfast, United Kingdom
| | - Colin E. Willoughby
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Meriel McEntagart
- Medical Genetics Unit, St George's University of London, London, United Kingdom
| | - Peng Tee Khaw
- Moorfields Eye Hospital, London, UK and University College London, Institute of Ophthalmology, London, United Kingdom
| | - Carol Clericuzio
- Department of Pediatric Genetics, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, United States of America
| | | | - Denise Williams
- Clinical Genetics Unit, Birmingham Women's Hospital, Birmingham, United Kingdom
| | - Ruth Newbury-Ecob
- Department of Clinical Genetics, University Hospitals, Bristol, United Kingdom
| | - Elias I. Traboulsi
- Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH, United States of America
| | - Eduardo D. Silva
- Department Ophthalmology, University Hospital of Coimbra, Coimbra, Portugal
| | - Mukhlis M. Madlom
- Children's Hospital, Doncaster Royal Infirmary, Doncaster, United Kingdom
| | - David R. Goudie
- Human Genetics Unit, University of Dundee College of Medicine, Dentistry and Nursing, Ninewells Hospital, Dundee, United Kingdom
| | - Brian W. Fleck
- Department of Ophthalmology, Princess Alexandra Eye Pavilion, Chalmers Street, Edinburgh, United Kingdom
| | - Dagmar Wieczorek
- Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Essen, Germany
- Institut für Humangenetik, Universitätsklinikum Düsseldorf, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | | | - Alice D. McTrusty
- Department of Life Sciences, Glasgow Caledonian University, Glasgow, United Kingdom
| | - Carol Gardiner
- Clinical Genetics, Southern General Hospital, Glasgow, United Kingdom
| | - Christopher Yale
- Department of Paediatrics and Child Health, Ipswich Hospital, Ipswich, United Kingdom
| | - Anthony T. Moore
- Moorfields Eye Hospital, London, UK and University College London, Institute of Ophthalmology, London, United Kingdom
| | - Isabelle Russell-Eggitt
- Institute of Child Health, University College London, UK and Great Ormond Street Hospital for Children, London, United Kingdom
| | - Lily Islam
- Institute of Child Health, University College London, UK and Great Ormond Street Hospital for Children, London, United Kingdom
| | - Melissa Lees
- North East Thames Regional Genetics Service, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street Hospital, London, United Kingdom
| | - Philip L. Beales
- Institute of Child Health, University College London, UK and Great Ormond Street Hospital for Children, London, United Kingdom
| | - Stephen J. Tuft
- Moorfields Eye Hospital, London, UK and University College London, Institute of Ophthalmology, London, United Kingdom
| | - Juan B. Solano
- Ruber International Hospital, Medical Genetics Unit, Mirasierra, Madrid, Spain
| | - Miranda Splitt
- Northern Genetics Service, Institute of Genetic Medicine, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle Upon Tyne, United Kingdom
| | - Jens Michael Hertz
- Department of Clinical Genetics, Odense University Hospital, Odense C, Denmark
| | - Trine E. Prescott
- Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Deborah J. Shears
- Department of Clinical Genetics, Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford, United Kingdom
| | - Ken K. Nischal
- UPMC Eye Center, Children's Hospital of Pittsburgh of UPMC, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | | | - Fabienne Prieur
- CHU de Saint Etienne, Service de génétique médicale, Saint-Etienne, France
| | - I. Karen Temple
- Academic Unit of Genetic Medicine, Division of Human Genetics, University of Southampton, Southampton, United Kingdom
| | - Katherine L. Lachlan
- Wessex Clinical Genetics Service, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Giuseppe Damante
- Department of Medical and Biological Sciences, University of Udine, Udine, Italy
| | - Danny A. Morrison
- St. Thomas’ Hospital, Westminster Bridge Road, London, United Kingdom
| | - Veronica van Heyningen
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - David R. FitzPatrick
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
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23
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Welsh IC, Kwak H, Chen FL, Werner M, Shopland LS, Danko CG, Lis JT, Zhang M, Martin JF, Kurpios NA. Chromatin Architecture of the Pitx2 Locus Requires CTCF- and Pitx2-Dependent Asymmetry that Mirrors Embryonic Gut Laterality. Cell Rep 2015; 13:337-49. [PMID: 26411685 PMCID: PMC4617833 DOI: 10.1016/j.celrep.2015.08.075] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 07/20/2015] [Accepted: 08/24/2015] [Indexed: 11/24/2022] Open
Abstract
Expression of Pitx2 on the left side of the embryo patterns left-right (LR) organs including the dorsal mesentery (DM), whose asymmetric cell behavior directs gut looping. Despite the importance of organ laterality, chromatin-level regulation of Pitx2 remains undefined. Here, we show that genes immediately neighboring Pitx2 in chicken and mouse, including a long noncoding RNA (Pitx2 locus-asymmetric regulated RNA or Playrr), are expressed on the right side and repressed by Pitx2. CRISPR/Cas9 genome editing of Playrr, 3D fluorescent in situ hybridization (FISH), and variations of chromatin conformation capture (3C) demonstrate that mutual antagonism between Pitx2 and Playrr is coordinated by asymmetric chromatin interactions dependent on Pitx2 and CTCF. We demonstrate that transcriptional and morphological asymmetries driving gut looping are mirrored by chromatin architectural asymmetries at the Pitx2 locus. We propose a model whereby Pitx2 auto-regulation directs chromatin topology to coordinate LR transcription of this locus essential for LR organogenesis.
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Affiliation(s)
- Ian C Welsh
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Hojoong Kwak
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Frances L Chen
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Melissa Werner
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Lindsay S Shopland
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Eastern Maine Medical Center Cancer Care, 33 Whiting Hill Road, Brewer, ME 04412, USA
| | - Charles G Danko
- Department of Biomedical Sciences, The Baker Institute for Animal Health, Cornell University, Ithaca, NY 14853, USA
| | - John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Min Zhang
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - James F Martin
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Heart Institute, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Natasza A Kurpios
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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24
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Wiggs JL. Glaucoma Genes and Mechanisms. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 134:315-42. [PMID: 26310163 DOI: 10.1016/bs.pmbts.2015.04.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genetic studies have yielded important genes contributing to both early-onset and adult-onset forms of glaucoma. The proteins encoded by the current collection of glaucoma genes participate in a broad range of cellular processes and biological systems. Approximately half the glaucoma-related genes function in the extracellular matrix, however proteins involved in cytokine signaling, lipid metabolism, membrane biology, regulation of cell division, autophagy, and ocular development also contribute to the disease pathogenesis. While the function of these proteins in health and disease are not completely understood, recent studies are providing insight into underlying disease mechanisms, a critical step toward the development of gene-based therapies. In this review, genes known to cause early-onset glaucoma or contribute to adult-onset glaucoma are organized according to the cell processes or biological systems that are impacted by the function of the disease-related protein product.
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Affiliation(s)
- Janey L Wiggs
- Harvard Medical School, and Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA.
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25
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Allen KF, Gaier ED, Wiggs JL. Genetics of Primary Inherited Disorders of the Optic Nerve: Clinical Applications. Cold Spring Harb Perspect Med 2015; 5:a017277. [PMID: 26134840 DOI: 10.1101/cshperspect.a017277] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inherited disorders of the optic nerve significantly impact vision in children and adults. The optic nerve disorders most commonly encountered clinically are glaucoma and primary optic neuropathy including Leber's hereditary optic neuropathy (LHON) and autosomal dominant or Kjer's optic atrophy. Current knowledge of the genetics of optic neuropathy and glaucoma makes it possible to test for mutations in disease-causing genes allowing for presymptomatic testing and risk assessment, and recent advances have revealed important disease mechanisms that may suggest potential therapeutic targets. In this perspective, we describe the current approaches and limitations to genetic testing for these disorders and provide an update on the development of gene-based therapies.
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Affiliation(s)
- Keri F Allen
- Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
| | - Eric D Gaier
- Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
| | - Janey L Wiggs
- Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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26
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Hehir-Kwa JY, Pfundt R, Veltman JA. Exome sequencing and whole genome sequencing for the detection of copy number variation. Expert Rev Mol Diagn 2015; 15:1023-32. [PMID: 26088785 DOI: 10.1586/14737159.2015.1053467] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Many laboratories now use genomic microarrays as their first-tier diagnostic test for copy number variation (CNV) detection. In addition, whole exome sequencing is increasingly being offered as a diagnostic test for heterogeneous disorders. Although mostly used for the detection of point mutations and small insertion-deletions, exome sequencing can also be used to call CNVs, allowing combined small and large variant analysis. Whole genome sequencing in addition to these advantages also offers the potential to characterize CNVs to unprecedented levels of accuracy, providing position and orientation information. In this review, we discuss the clinical potential of CNV identification in whole exome sequencing and whole genome sequencing data and the implications this has on diagnostic laboratories.
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Affiliation(s)
- Jayne Y Hehir-Kwa
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
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27
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Schilter KF, Reis LM, Sorokina EA, Semina EV. Identification of an Alu-repeat-mediated deletion of OPTN upstream region in a patient with a complex ocular phenotype. Mol Genet Genomic Med 2015; 3:490-9. [PMID: 26740941 PMCID: PMC4694134 DOI: 10.1002/mgg3.159] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 05/05/2015] [Accepted: 05/08/2015] [Indexed: 12/14/2022] Open
Abstract
Genetic causes of ocular conditions remain largely unknown. To reveal the molecular basis for a congenital ocular phenotype associated with glaucoma we performed whole‐exome sequencing (WES) and whole‐genome copy number analyses of patient DNA. WES did not identify a causative variant. Copy number variation analysis identified a deletion of 10p13 in the patient and his unaffected father; the deletion breakpoint contained a single 37‐bp sequence that is normally present in two distinct Alu repeats separated by ~181 kb. The deletion removed part of the upstream region of optineurin (OPTN) as well as the upstream sequence and two coding exons of coiled‐coil domain containing 3 (CCDC3); analysis of the patient's second allele showed normal OPTN and CCDC3 sequences. Studies of zebrafish orthologs identified expression in the developing eye for both genes. OPTN is a known factor in dominant adult‐onset glaucoma and Amyotrophic Lateral Sclerosis (ALS). The deletion eliminates 98 kb of the OPTN upstream sequence leaving only ~1 kb of the proximal promoter region. Comparison of transcriptional activation capability of the 3 kb normal and the rearranged del(10)(p13) OPTN promoter sequences demonstrated a statistically significant decrease for the deleted allele; sequence analysis of the entire deleted region identified multiple conserved elements with possible cis‐regulatory activity. Additional screening of CCDC3 indicated that heterozygous loss‐of‐function alleles are unlikely to cause congenital ocular disease. In summary, we report the first regulatory region deletion involving OPTN, caused by Alu‐mediated nonallelic homologous recombination and possibly contributing to the patient's ocular phenotype. In addition, our data indicate that Alu‐mediated rearrangements of the OPTN upstream region may represent a new source of affected alleles in human conditions. Evaluation of the upstream OPTN sequences in additional ocular and ALS patients may help to determine the role of this region, if any, in human disease.
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Affiliation(s)
- Kala F Schilter
- Department of Pediatrics and Children's Research InstituteMedical College of WisconsinMilwaukeeWisconsin53226; Department of Cell Biology, Neurobiology and AnatomyMedical College of WisconsinMilwaukeeWisconsin53226
| | - Linda M Reis
- Department of Pediatrics and Children's Research Institute Medical College of Wisconsin Milwaukee Wisconsin 53226
| | - Elena A Sorokina
- Department of Pediatrics and Children's Research Institute Medical College of Wisconsin Milwaukee Wisconsin 53226
| | - Elena V Semina
- Department of Pediatrics and Children's Research InstituteMedical College of WisconsinMilwaukeeWisconsin53226; Department of Cell Biology, Neurobiology and AnatomyMedical College of WisconsinMilwaukeeWisconsin53226
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28
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Erokhin M, Vassetzky Y, Georgiev P, Chetverina D. Eukaryotic enhancers: common features, regulation, and participation in diseases. Cell Mol Life Sci 2015; 72:2361-75. [PMID: 25715743 PMCID: PMC11114076 DOI: 10.1007/s00018-015-1871-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 02/07/2015] [Accepted: 02/20/2015] [Indexed: 01/01/2023]
Abstract
Enhancers are positive DNA regulatory sequences controlling temporal and tissue-specific gene expression. These elements act independently of their orientation and distance relative to the promoters of target genes. Enhancers act through a variety of transcription factors that ensure their correct match with target promoters and consequent gene activation. There is a growing body of evidence on association of enhancers with transcription factors, co-activators, histone chromatin marks, and lncRNAs. Alterations in enhancers lead to misregulation of gene expression, causing a number of human diseases. In this review, we focus on the common characteristics of enhancers required for transcription stimulation.
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Affiliation(s)
- Maksim Erokhin
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334 Russia
- LIA 1066, Laboratoire Franco-Russe de recherche en oncologie, 119334 Moscow, Russia
| | - Yegor Vassetzky
- LIA 1066, Laboratoire Franco-Russe de recherche en oncologie, 119334 Moscow, Russia
- UMR8126, Université Paris-Sud, CNRS, Institut de cancérologie Gustave Roussy, 94805 Villejuif, France
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334 Russia
- LIA 1066, Laboratoire Franco-Russe de recherche en oncologie, 119334 Moscow, Russia
| | - Darya Chetverina
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334 Russia
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29
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Aguirre LA, Alonso ME, Badía-Careaga C, Rollán I, Arias C, Fernández-Miñán A, López-Jiménez E, Aránega A, Gómez-Skarmeta JL, Franco D, Manzanares M. Long-range regulatory interactions at the 4q25 atrial fibrillation risk locus involve PITX2c and ENPEP. BMC Biol 2015; 13:26. [PMID: 25888893 PMCID: PMC4416339 DOI: 10.1186/s12915-015-0138-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 04/10/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Recent genome-wide association studies have uncovered genomic loci that underlie an increased risk for atrial fibrillation, the major cardiac arrhythmia in humans. The most significant locus is located in a gene desert at 4q25, approximately 170 kilobases upstream of PITX2, which codes for a transcription factor involved in embryonic left-right asymmetry and cardiac development. However, how this genomic region functionally and structurally relates to PITX2 and atrial fibrillation is unknown. RESULTS To characterise its function, we tested genomic fragments from 4q25 for transcriptional activity in a mouse atrial cardiomyocyte cell line and in transgenic mouse embryos, identifying a non-tissue-specific potentiator regulatory element. Chromosome conformation capture revealed that this region physically interacts with the promoter of the cardiac specific isoform of Pitx2. Surprisingly, this regulatory region also interacts with the promoter of the next neighbouring gene, Enpep, which we show to be expressed in regions of the developing mouse heart essential for cardiac electrical activity. CONCLUSIONS Our data suggest that de-regulation of both PITX2 and ENPEP could contribute to an increased risk of atrial fibrillation in carriers of disease-associated variants, and show the challenges that we face in the functional analysis of genome-wide disease associations.
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Affiliation(s)
- Luis A Aguirre
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029, Madrid, Spain.
| | - M Eva Alonso
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029, Madrid, Spain.
| | - Claudio Badía-Careaga
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029, Madrid, Spain.
| | - Isabel Rollán
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029, Madrid, Spain.
| | - Cristina Arias
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029, Madrid, Spain.
| | - Ana Fernández-Miñán
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, ctra. de Utrera km1, 41013, Seville, Spain.
| | - Elena López-Jiménez
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029, Madrid, Spain.
| | - Amelia Aránega
- Department of Experimental Biology, Faculty of Experimental Sciences, University of Jaen, Paraje de las Lagunillas s/n, 23071, Jaén, Spain.
| | - José Luis Gómez-Skarmeta
- Centro Andaluz de Biología del Desarrollo (CABD), CSIC-Universidad Pablo de Olavide-Junta de Andalucía, ctra. de Utrera km1, 41013, Seville, Spain.
| | - Diego Franco
- Department of Experimental Biology, Faculty of Experimental Sciences, University of Jaen, Paraje de las Lagunillas s/n, 23071, Jaén, Spain.
| | - Miguel Manzanares
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029, Madrid, Spain.
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30
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Abstract
The characterization of genes responsible for glaucoma is the critical first step toward the development of gene-based diagnostic and screening tests, which could identify individuals at risk for disease before irreversible optic nerve damage occurs. Early-onset forms of glaucoma affecting children and young adults are typically inherited as Mendelian autosomal dominant or recessive traits whereas glaucoma affecting older adults has complex inheritance. In this report, we present a comprehensive overview of the genes and genomic regions contributing to inherited glaucoma.
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Affiliation(s)
- Ryan Wang
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
| | - Janey L Wiggs
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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31
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Titheradge H, Togneri F, McMullan D, Brueton L, Lim D, Williams D. Axenfeld-Rieger syndrome: further clinical and array delineation of four unrelated patients with a 4q25 microdeletion. Am J Med Genet A 2014; 164A:1695-701. [PMID: 24715413 DOI: 10.1002/ajmg.a.36540] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 02/14/2014] [Indexed: 11/06/2022]
Abstract
Axenfeld-Rieger syndrome (ARS) is an autosomal dominant disorder with variable expressivity. It is characterized by dysgenesis of the anterior segment of the eye together with dental, cardiac, and umbilical anomalies. There is a high incidence of secondary high tension glaucoma. It is a genetically heterogeneous condition due to deletion or mutations of FOXC1 (6p25) or PITX2 (4q25). We report on four unrelated patients with overlapping microdeletions encompassing PITX2 at 4q25. We compare the genotypes and phenotypes of these newly described ARS patients and discuss the involvement of contiguous genes. Patients 1, 2, and 3 had mild learning difficulties, not typically seen in patients with ARS. We implicate the adjacent neuronally expressed genes; NEUROG2, UGT8, NDST3, and PRSS12 as potentially causal. Our findings support the use of microarray analysis in ARS patients for full prognostic information in infants presenting with ARS-like phenotypes.
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Affiliation(s)
- Hannah Titheradge
- Department of Clinical Genetics, Birmingham Women's NHS Foundation Trust, Birmingham, United Kingdom
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32
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Weh E, Reis LM, Tyler RC, Bick D, Rhead WJ, Wallace S, McGregor TL, Dills SK, Chao MC, Murray JC, Semina EV. Novel B3GALTL mutations in classic Peters plus syndrome and lack of mutations in a large cohort of patients with similar phenotypes. Clin Genet 2013; 86:142-8. [PMID: 23889335 DOI: 10.1111/cge.12241] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/17/2013] [Accepted: 07/17/2013] [Indexed: 11/30/2022]
Abstract
Peters plus syndrome (PPS) is a rare autosomal-recessive disorder characterized by Peters anomaly of the eye, short stature, brachydactyly, dysmorphic facial features, developmental delay, and variable other systemic abnormalities. In this report, we describe screening of 64 patients affected with PPS, isolated Peters anomaly and PPS-like phenotypes. Mutations in the coding region of B3GALTL were identified in nine patients; six had a documented phenotype of classic PPS and the remaining three had a clinical diagnosis of PPS with incomplete clinical documentation. A total of nine different pathogenic alleles were identified. Five alleles are novel including one frameshift, c.168dupA, p.(Gly57Argfs*11), one nonsense, c.1234C>T, p.(Arg412*), two missense, c.1045G>A, p.(Asp349Asn) and c.1181G>A, p.(Gly394Glu), and one splicing, c.347+5G>T, mutations. Consistent with previous reports, the c.660+1G>A mutation was the most common mutation identified, seen in eight of the nine patients and accounting for 55% of pathogenic alleles in this study and 69% of all reported pathogenic alleles; while two patients were homozygous for this mutation, the majority had a second rare pathogenic allele. We also report the absence of B3GALTL mutations in 55 cases of PPS-like phenotypes or isolated Peters anomaly, further establishing the strong association of B3GALTL mutations with classic PPS only.
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Affiliation(s)
- E Weh
- Department of Pediatrics, Children's Research Institute, Medical College of Wisconsin, Children's Hospital of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
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Verhoeven WM, Egger JI, Goffin L, van Zutven LJ, Mancini GM. Behavioural phenotype of a patient with a de novo 1.2 Mb chromosome 4q25 microdeletion. Eur J Med Genet 2013; 56:331-5. [DOI: 10.1016/j.ejmg.2013.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/11/2013] [Indexed: 11/27/2022]
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Spielmann M, Klopocki E. CNVs of noncoding cis-regulatory elements in human disease. Curr Opin Genet Dev 2013; 23:249-56. [PMID: 23601627 DOI: 10.1016/j.gde.2013.02.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/08/2013] [Accepted: 02/25/2013] [Indexed: 12/22/2022]
Abstract
Genomic rearrangements and copy-number variations (CNVs) are structural aberrations of the human genome which contribute to phenotypic variation as well as human disease. By now it is well accepted that structural aberrations affecting coding regions can have pathogenic effects, however, noncoding variants have only recently come into focus as disease-associated variants. The phenotypes associated with alterations in noncoding regions with regulatory potential can be striking and at the same time confined to a certain tissue/organ. Future studies will elucidate the frequency of these changes which are expected to be higher among conditions that are due to disturbance of complex developmental processes. Integrating these data with the recently published data from the ENCODE project will broaden our view of genes and their regulation and contribute to our understanding of pathomechanism underlying human disease. In this article, we review the recent advances in the identification of genomic rearrangements and CNVs in noncoding regions of the genome and their consequences for human disease.
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Affiliation(s)
- Malte Spielmann
- Institute for Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Reis LM, Tyler RC, Volkmann Kloss BA, Schilter KF, Levin AV, Lowry RB, Zwijnenburg PJG, Stroh E, Broeckel U, Murray JC, Semina EV. PITX2 and FOXC1 spectrum of mutations in ocular syndromes. Eur J Hum Genet 2012; 20:1224-33. [PMID: 22569110 PMCID: PMC3499749 DOI: 10.1038/ejhg.2012.80] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 02/22/2012] [Accepted: 02/29/2012] [Indexed: 02/01/2023] Open
Abstract
Anterior segment dysgenesis (ASD) encompasses a broad spectrum of developmental conditions affecting anterior ocular structures and associated with an increased risk for glaucoma. Various systemic anomalies are often observed in ASD conditions such as Axenfeld-Rieger syndrome (ARS) and De Hauwere syndrome. We report DNA sequencing and copy number analysis of PITX2 and FOXC1 in 76 patients with syndromic or isolated ASD and related conditions. PITX2 mutations and deletions were found in 24 patients with dental and/or umbilical anomalies seen in all. Seven PITX2-mutant alleles were novel including c.708_730del, the most C-terminal mutation reported to date. A second case of deletion of the distant upstream but not coding region of PITX2 was identified, highlighting the importance of this recently discovered mechanism for ARS. FOXC1 deletions were observed in four cases, three of which demonstrated hearing and/or heart defects, including a patient with De Hauwere syndrome; no nucleotide mutations in FOXC1 were identified. Review of the literature identified several other patients with 6p25 deletions and features of De Hauwere syndrome. The 1.3-Mb deletion of 6p25 presented here defines the critical region for this phenotype and includes the FOXC1, FOXF2, and FOXQ1 genes. In summary, PITX2 or FOXC1 disruptions explained 63% of ARS and 6% of other ASD in our cohort; all affected patients demonstrated additional systemic defects with PITX2 mutations showing a strong association with dental and/or umbilical anomalies and FOXC1 with heart and hearing defects. FOXC1 deletion was also found to be associated with De Hauwere syndrome.
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Affiliation(s)
- Linda M Reis
- Department of Pediatrics and Children's Research Institute, Milwaukee, WI, USA
| | - Rebecca C Tyler
- Department of Pediatrics and Children's Research Institute, Milwaukee, WI, USA
| | - Bethany A Volkmann Kloss
- Department of Pediatrics and Children's Research Institute, Milwaukee, WI, USA
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Kala F Schilter
- Department of Pediatrics and Children's Research Institute, Milwaukee, WI, USA
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Alex V Levin
- Pediatric Ophthalmology and Ocular Genetics, Wills Eye Institute, Thomas Jefferson University, Philadelphia, PA, USA
| | - R Brian Lowry
- Department of Medical Genetics, Alberta Children's Hospital and University of Calgary, Calgary, AB, Canada
| | - Petra J G Zwijnenburg
- Department of Clinical Genetics, VU University Medical Centre, Amsterdam, HV, The Netherlands
| | - Eliza Stroh
- Pediatric Ophthalmology and Ocular Genetics, Wills Eye Institute, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ulrich Broeckel
- Department of Pediatrics and Children's Research Institute, Milwaukee, WI, USA
| | - Jeffrey C Murray
- Department of Pediatrics, The University of Iowa, Iowa City, IA, USA
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Milwaukee, WI, USA
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
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Genin A, Desir J, Lambert N, Biervliet M, Van Der Aa N, Pierquin G, Killian A, Tosi M, Urbina M, Lefort A, Libert F, Pirson I, Abramowicz M. Kinetochore KMN network gene CASC5 mutated in primary microcephaly. Hum Mol Genet 2012; 21:5306-17. [PMID: 22983954 DOI: 10.1093/hmg/dds386] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Several genes expressed at the centrosome or spindle pole have been reported to underlie autosomal recessive primary microcephaly (MCPH), a neurodevelopmental disorder consisting of an important brain size reduction present since birth, associated with mild-to-moderate mental handicap and no other neurological feature nor associated malformation. Here, we report a mutation of CASC5 (aka Blinkin, or KNL1, or hSPC105) in MCPH patients from three consanguineous families, in one of which we initially reported the MCPH4 locus. The combined logarithm of odds score of the three families was >6. All patients shared a very rare homozygous mutation of CASC5. The mutation induced skipping of exon 18 with subsequent frameshift and truncation of the predicted protein. CASC5 is part of the KMN network of the kinetochore and is required for proper microtubule attachment to the chromosome centromere and for spindle-assembly checkpoint (SAC) activation during mitosis. Like MCPH gene ASPM, CASC5 is upregulated in the ventricular zone (VZ) of the human fetal brain. CASC5 binds BUB1, BUBR1, ZWINT-1 and interestingly it binds to MIS12 through a protein domain which is truncated by the mutation. CASC5 localized at the equatorial plate like ZWINT-1 and BUBR1, while ASPM, CEP152 and PCTN localized at the spindle poles in our patients and in controls. Comparison of primate and rodent lineages indicates accelerated evolution of CASC5 in the human lineage. Our data provide strong evidence for CASC5 as a novel MCPH gene, and underscore the role of kinetochore integrity in proper volumetric development of the human brain.
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Affiliation(s)
- Anne Genin
- Institute of Interdisciplinary Research IRIBHM , Université Libre de Bruxelles, Anderlecht, Belgium
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Kloss BAV, Reis LM, Brémond-Gignac D, Glaser T, Semina EV. Analysis of FOXD3 sequence variation in human ocular disease. Mol Vis 2012; 18:1740-9. [PMID: 22815627 PMCID: PMC3398501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 06/23/2012] [Indexed: 11/23/2022] Open
Abstract
PURPOSE The migratory neural crest cell population makes a significant contribution to the anterior segment structures of the eye. Consequently, several anterior segment dysgenesis phenotypes are associated with mutations in genes expressed during neural crest development. The forkhead box D3 (FOXD3) gene encodes a forkhead transcription factor that plays an important role in neural crest specification in vertebrates and therefore may be involved in human eye disease. METHODS We screened 310 probands with developmental ocular conditions for variations in FOXD3. RESULTS Six nonsynonymous FOXD3 variants were identified. Four of these changes, c.47C>T (p.Thr16Met), c.359C>T (p.Pro120Leu), c.517A>C (p.Asn173His), and c.818_829dup (p.Arg273_Gly276dup), affected conserved regions and were observed primarily in probands with aniridia or Peters anomaly; out of these four variants, one, p.Arg273_Gly276dup, was not detected in control populations and two, p.Pro120Leu and p.Asn173His, were statistically enriched in cases with aniridia or Peters anomaly. The p.Arg273_Gly276dup variant was seen in a proband with aniridia as well as two additional unrelated probands affected with anophthalmia or congenital cataracts. The p.Asn173His variant affects Helix 2 of the DNA-binding domain and was observed in two unrelated patients with Peters anomaly or aniridia; in both cases, one parent carried the same allele. CONCLUSIONS FOXD3 variants increase the risk of anterior segment dysgenesis phenotypes in humans. The p.Asn173His mutation affects a residue in the forkhead domain that is 100% conserved among vertebrate orthologs and is predicted to participate in protein-protein interactions. Its phenotypic effects may be modulated by transcriptional cofactors which have yet to be identified.
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Affiliation(s)
- Bethany A. Volkmann Kloss
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, WI,Department of Cell Biology, Neurobiology and Anatomy at the Medical College of Wisconsin, Milwaukee, WI
| | - Linda M. Reis
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, WI
| | - Dominique Brémond-Gignac
- Department of Pediatric Ophthalmology, St Victor University Hospital of Amiens and Vision Institute, Picardie Jules Verne University, Amiens, France
| | - Tom Glaser
- Departments of Internal Medicine and Human Genetics, University of Michigan, Ann Arbor, MI
| | - Elena V. Semina
- Department of Pediatrics and Children’s Research Institute at the Medical College of Wisconsin and Children’s Hospital of Wisconsin, Milwaukee, WI,Department of Cell Biology, Neurobiology and Anatomy at the Medical College of Wisconsin, Milwaukee, WI
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Liu Y, Semina EV. pitx2 Deficiency results in abnormal ocular and craniofacial development in zebrafish. PLoS One 2012; 7:e30896. [PMID: 22303467 PMCID: PMC3267762 DOI: 10.1371/journal.pone.0030896] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 12/23/2011] [Indexed: 11/18/2022] Open
Abstract
Human PITX2 mutations are associated with Axenfeld-Rieger syndrome, an autosomal-dominant developmental disorder that involves ocular anterior segment defects, dental hypoplasia, craniofacial dysmorphism and umbilical abnormalities. Characterization of the PITX2 pathway and identification of the mechanisms underlying the anomalies associated with PITX2 deficiency is important for better understanding of normal development and disease; studies of pitx2 function in animal models can facilitate these analyses. A knockdown of pitx2 in zebrafish was generated using a morpholino that targeted all known alternative transcripts of the pitx2 gene; morphant embryos generated with the pitx2(ex4/5) splicing-blocking oligomer produced abnormal transcripts predicted to encode truncated pitx2 proteins lacking the third (recognition) helix of the DNA-binding homeodomain. The morphological phenotype of pitx2(ex4/5) morphants included small head and eyes, jaw abnormalities and pericardial edema; lethality was observed at ∼6-8-dpf. Cartilage staining revealed a reduction in size and an abnormal shape/position of the elements of the mandibular and hyoid pharyngeal arches; the ceratobranchial arches were also decreased in size. Histological and marker analyses of the misshapen eyes of the pitx2(ex4/5) morphants identified anterior segment dysgenesis and disordered hyaloid vasculature. In summary, we demonstrate that pitx2 is essential for proper eye and craniofacial development in zebrafish and, therefore, that PITX2/pitx2 function is conserved in vertebrates.
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Affiliation(s)
- Yi Liu
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Elena V. Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
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Abstract
PURPOSE OF REVIEW Anterior segment dysgenesis (ASD) disorders encompass a spectrum of developmental conditions affecting the cornea, iris, and lens and are generally associated with an approximate 50% risk for glaucoma. These conditions are characterized by both autosomal dominant and recessive patterns of inheritance often with incomplete penetrance/variable expressivity. This article summarizes what is known about the genetics of ASD disorders and reviews recent developments. RECENT FINDINGS Mutations in Collagen type IV alpha-1 (COL4A1) and Beta-1,3-galactosyltransferase-like (B3GALTL) have been reported in ASD patients. Novel findings in other well known ocular genes are also presented, among which regulatory region deletions in PAX6 and PITX2 are most notable. SUMMARY Although a number of genetic causes have been identified, many ASD conditions are still awaiting genetic elucidation. The majority of characterized ASD genes encode transcription factors; several other genes represent extracellular matrix-related proteins. All of the involved genes play active roles in ocular development and demonstrate conserved functions across species. The use of novel technologies, such as whole genome sequencing/comparative genomic hybridization, is likely to broaden the mutation spectrums in known genes and assist in the identification of novel causative genes as well as modifiers explaining the phenotypic variability of ASD conditions.
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Makarenkova HP, Meech R. Barx homeobox family in muscle development and regeneration. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 297:117-73. [PMID: 22608559 DOI: 10.1016/b978-0-12-394308-8.00004-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Homeobox transcription factors are key intrinsic regulators of myogenesis. In studies spanning several years, we have characterized the homeobox factor Barx2 as a novel marker for muscle progenitor cells and an important regulator of muscle growth and repair. In this review, we place the expression and function of Barx2 and its paralogue Barx1 in context with other muscle-expressed homeobox factors in both embryonic and adult myogenesis. We also describe the structure and regulation of Barx genes and possible gene/disease associations. The functional domains of Barx proteins, their molecular interactions, and cellular functions are presented with particular emphasis on control of genes and processes involved in myogenic differentiation. Finally, we describe the patterns of Barx gene expression in vivo and the phenotypes of various Barx gene perturbation models including null mice. We focus on the Barx2 null mouse model, which has demonstrated the critical roles of Barx2 in postnatal myogenesis including muscle maintenance during aging, and regeneration of acute and chronic muscle injury.
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Affiliation(s)
- Helen P Makarenkova
- The Neurobiology Department, Scripps Research Institute, La Jolla, California, USA
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Strungaru MH, Footz T, Liu Y, Berry FB, Belleau P, Semina EV, Raymond V, Walter MA. PITX2 is involved in stress response in cultured human trabecular meshwork cells through regulation of SLC13A3. Invest Ophthalmol Vis Sci 2011; 52:7625-33. [PMID: 21873665 PMCID: PMC3183983 DOI: 10.1167/iovs.10-6967] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 05/17/2011] [Accepted: 06/04/2011] [Indexed: 10/17/2022] Open
Abstract
PURPOSE Mutations of the PITX2 gene cause Axenfeld-Rieger syndrome (ARS) and glaucoma. In this study, the authors investigated genes directly regulated by the PITX2 transcription factor to gain insight into the mechanisms underlying these disorders. METHODS RNA from nonpigmented ciliary epithelium cells transfected with hormone-inducible PITX2 and activated by mifepristone was subjected to microarray analyses. Data were analyzed using dCHIP algorithms to detect significant differences in expression. Genes with significantly altered expression in multiple microarray experiments in the presence of activated PITX2 were subjected to in silico and biochemical analyses to validate them as direct regulatory targets. One target gene was further characterized by studying the effect of its knockdown in a cell model of oxidative stress, and its expression in zebrafish embryos was analyzed by in situ hybridization. RESULTS Solute carrier family 13 sodium-dependent dicarboxylate transporter member 3 (SLC13A3) was identified as 1 of 47 potential PITX2 target genes in ocular cells. PITX2 directly regulates SLC13A3 expression, as demonstrated by luciferase reporter and chromatin immunoprecipitation assays. Reduction of PITX2 or SLC13A3 levels by small interfering RNA (siRNA)-mediated knockdown augmented the death of transformed human trabecular meshwork cells exposed to hydrogen peroxide. Zebrafish slc13a3 is expressed in anterior ocular regions in a pattern similar to that of pitx2. CONCLUSIONS The results indicate that SLC13A3 is a direct downstream target of PITX2 transcriptional regulation and that levels of PITX2 and SLC13A3 modulate responses to oxidative stress in ocular cells.
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Affiliation(s)
| | - Tim Footz
- From the Departments of Medical Genetics and
| | - Yi Liu
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin
| | - Fred B. Berry
- From the Departments of Medical Genetics and
- Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Pascal Belleau
- Department of Molecular Medicine, Université Laval, Québec City, Quebec, Canada; and
| | - Elena V. Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, Wisconsin
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Vincent Raymond
- Department of Molecular Medicine, Université Laval, Québec City, Quebec, Canada; and
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