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Gillis RF, Palmour RM. mRNA expression analysis of the hippocampus in a vervet monkey model of fetal alcohol spectrum disorder. J Neurodev Disord 2022; 14:21. [PMID: 35305552 PMCID: PMC8934503 DOI: 10.1186/s11689-022-09427-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 02/10/2022] [Indexed: 11/12/2022] Open
Abstract
Background Fetal alcohol spectrum disorders (FASD) are common, yet preventable developmental disorders that stem from prenatal exposure to alcohol. This exposure leads to a wide array of behavioural and physical problems with a complex and poorly defined biological basis. Molecular investigations to date predominantly use rodent animal models, but because of genetic, developmental and social behavioral similarity, primate models are more relevant. We previously reported reduced cortical and hippocampal neuron levels in an Old World monkey (Chlorocebus sabaeus) model with ethanol exposure targeted to the period of rapid synaptogenesis and report here an initial molecular study of this model. The goal of this study was to evaluate mRNA expression of the hippocampus at two different behavioural stages (5 months, 2 years) corresponding to human infancy and early childhood. Methods Offspring of alcohol-preferring or control dams drank a maximum of 3.5 g ethanol per kg body weight or calorically matched sucrose solution 4 days per week during the last 2 months of gestation. Total mRNA expression was measured with the Affymetrix GeneChip Rhesus Macaque Genome Array in a 2 × 2 study design that interrogated two independent variables, age at sacrifice, and alcohol consumption during gestation. Results and discussion Statistical analysis identified a preferential downregulation of expression when interrogating the factor ‘alcohol’ with a balanced effect of upregulation vs. downregulation for the independent variable ‘age’. Functional exploration of both independent variables shows that the alcohol consumption factor generates broad functional annotation clusters that likely implicate a role for epigenetics in the observed differential expression, while the variable age reliably produced functional annotation clusters predominantly related to development. Furthermore, our data reveals a novel connection between EFNB1 and the FASDs; this is highly plausible both due to the role of EFNB1 in neuronal development as well as its central role in craniofrontal nasal syndrome (CFNS). Fold changes for key genes were subsequently confirmed via qRT-PCR. Conclusion Prenatal alcohol exposure leads to global downregulation in mRNA expression. The cellular interference model of EFNB1 provides a potential clue regarding how genetically susceptible individuals may develop the phenotypic triad generally associated with classic fetal alcohol syndrome. Supplementary Information The online version contains supplementary material available at 10.1186/s11689-022-09427-z.
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Gürsoy S, Hazan F, Öztürk T, Çolak R, Çalkavur Ş. Evaluation of Sporadic and Familial Cases with Craniofrontonasal Syndrome: A Wide Clinical Spectrum and Identification of a Novel EFNB1 Gene Mutation. Mol Syndromol 2021; 12:269-278. [PMID: 34602953 DOI: 10.1159/000515697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/05/2021] [Indexed: 11/19/2022] Open
Abstract
Craniofrontonasal syndrome (CFNS) is a rare X-linked genetic disorder which is characterized by coronal synostosis, widely spaced eyes, a central nasal groove, and various skeletal anomalies. Mutations in the EFNB1 gene in Xq13.1 are responsible for familial and sporadic cases. In the present study, we aimed to evaluate the clinical characteristics and molecular results of 4 patients with CFNS. Genomic DNA was extracted from the peripheral blood lymphocytes of all patients and their parents, and Sanger sequencing of the EFNB1 gene was performed. A novel EFNB1 gene mutation (c.65delG; p.Cys22SerfsTer24) was detected in a newborn who had only dysmorphic facial features and bicornuate uterus. The other 3 patients (2 familial cases and 1 sporadic case) shared the same mutation (c.196C>T; p.R66X). However, the clinical features of these patients were highly variable. Additionally, central (meso-axial) polydactyly and deep palmar creases were detected, which have not been previously reported. CFNS has a wide clinical spectrum, but there is no clear genotype-phenotype correlation. However, central (meso-axial) polydactyly and deep palmar creases may be part of the clinical spectrum seen in CFNS. In addition, our findings expand the mutational spectrum in patients with CFNS.
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Affiliation(s)
- Semra Gürsoy
- Department of Pediatric Genetics, Dr. Behcet Uz Children's Hospital, Izmir, Turkey
| | - Filiz Hazan
- Department of Medical Genetics, Dr. Behcet Uz Children's Hospital, Izmir, Turkey
| | - Tülay Öztürk
- Department of Pediatric Radiology, Dr. Behcet Uz Children's Hospital, Izmir, Turkey
| | - Rüya Çolak
- Department of Neonatology, Dr. Behcet Uz Children's Hospital, Izmir, Turkey
| | - Şebnem Çalkavur
- Department of Neonatology, Dr. Behcet Uz Children's Hospital, Izmir, Turkey
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3
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Han JY, Kim HJ, Jang JH, Lee IG, Park J. Trio-Based Whole-Exome Sequencing Identifies a De novo EFNB1 Mutation as a Genetic Cause in Female Infant With Brain Anomaly and Developmental Delay. Front Pediatr 2020; 8:461. [PMID: 32984200 PMCID: PMC7490291 DOI: 10.3389/fped.2020.00461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 06/30/2020] [Indexed: 11/23/2022] Open
Abstract
Background: Craniofrontonasal syndrome is a rare, X-linked disorder in which heterozygous females ironically reported the majority of patients and is caused by in the EFNB1 gene located at chromosome Xq13.1. Unlike previous reports, we present a female infant with a de novo EFNB1 missense mutation that was demonstrated in clinical diagnosis as global developmental delay (GDD) and brain anomaly without frontonasal dysplasia or other malformation. Case Presentation: This study reports the genetic analysis of a 4-month-old female infant presenting brain anomaly and GDD. She was the only child of unrelated parents. Early developmental was characterized by delays in fine motor, achieving gross motor, language, and social-cognitive milestones. She could not control her head or hold objects until 4 months of age. Brain magnetic resonance imaging revealed schizencephaly and dysgenesis of corpus callosum. Trio-based whole-exome sequencing revealed a heterozygous c.943C>T (p.Pro315Ser) in the EFNB1. Sanger sequencing confirmed this heterozygous alteration occurring in a dominant de novo manner, as a consequence of phenotypic and genotypic wild type in both parents. Conclusion: EFNB1 mutation is considered for a child with schizencephaly, and further study focusing on phenotyping is required to understand the possible contribution of environmental impact and genetic modifier in the expression of EFNB1.
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Affiliation(s)
- Ji Yoon Han
- Department of Pediatrics, College of Medicine, Catholic University of Korea, Seoul, South Korea
| | - Hyun Jeong Kim
- Department of Radiology, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Ja Hyun Jang
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - In Goo Lee
- Department of Pediatrics, College of Medicine, Catholic University of Korea, Seoul, South Korea
| | - Joonhong Park
- Department of Laboratory Medicine, College of Medicine, Catholic University of Korea, Seoul, South Korea.,Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju, South Korea
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4
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Jiang Y, Qian YQ, Yang MM, Zhan QT, Chen Y, Xi FF, Sagnelli M, Dong MY, Zhao BH, Luo Q. Whole-Exome Sequencing Revealed Mutations of MED12 and EFNB1 in Fetal Agenesis of the Corpus Callosum. Front Genet 2019; 10:1201. [PMID: 31824579 PMCID: PMC6886535 DOI: 10.3389/fgene.2019.01201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 10/30/2019] [Indexed: 11/29/2022] Open
Abstract
Agenesis of the corpus callosum (ACC) is a birth defect in which the corpus callosum is either partially or completely missing. With recent advances in prenatal ultrasound, detection of ACC in obstetric practices is becoming more common. Etiologies of ACC include chromosome errors, genetic factors, prenatal infections, and other factors related to the prenatal environment. In an effort to elucidate more about the genetic influence in the pathogenesis of ACC, we identified, through whole-exome sequencing (WES), two gene mutations in two families with complete agenesis of the corpus callosum. These two mutations are located on chromosome X: one is a hemizygous missense mutation c.3746T>C (p. L1249P) in the gene mediator complex subunit 12 (MED12); the other one is a heterozygous missense mutation c.128+5G>C in gene ephrin B1 (EFNB1). Historically, early diagnosis of complete ACC during pregnancy has been difficult; however, WES has provided us with a creative avenue of diagnosis, combining identification of genetic mutations with prenatal imaging.
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Affiliation(s)
- Ying Jiang
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Ye-Qing Qian
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Meng-Meng Yang
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Qi-Tao Zhan
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yuan Chen
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Fang-Fang Xi
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Matthew Sagnelli
- University of Connecticut School of Medicine, Farmington, CT, United States
| | - Min-Yue Dong
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Bai-Hui Zhao
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Qiong Luo
- Department of Obstetrics, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou, China
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5
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Abstract
In 1993, Jabs et al. were the first to describe a genetic origin of craniosynostosis. Since this discovery, the genetic causes of the most common syndromes have been described. In 2015, a total of 57 human genes were reported for which there had been evidence that mutations were causally related to craniosynostosis. Facilitated by rapid technological developments, many others have been identified since then. Reviewing the literature, we characterize the most common craniosynostosis syndromes followed by a description of the novel causes that were identified between January 2015 and December 2017.
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Affiliation(s)
- Jacqueline A C Goos
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Irene M J Mathijssen
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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6
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Romanelli Tavares VL, Kague E, Musso CM, Alegria TGP, Freitas RS, Bertola DR, Twigg SRF, Passos-Bueno MR. Craniofrontonasal Syndrome Caused by Introduction of a Novel uATG in the 5'UTR of EFNB1. Mol Syndromol 2018; 10:40-47. [PMID: 30976278 DOI: 10.1159/000490635] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Craniofrontonasal syndrome (CFNS) is an X-linked disorder caused by EFNB1 mutations in which females are more severely affected than males. Severe male phenotypes are associated with mosaicism, supporting cellular interference for sex bias in this disease. Although many variants have been found in the coding region of EFNB1, only 2 pathogenic variants have been identified in the same nucleotide in 5'UTR, disrupting the stop codon of an upstream open reading frame (uORF). uORFs are known to be part of a wide range of post-transcriptional regulation processes, and just recently, their association with human diseases has come to light. In the present study, we analyzed EFNB1 in a female patient with typical features of CFNS. We identified a variant, located at c.-411, creating a new upstream ATG (uATG) in the 5'UTR of EFNB1, which is predicted to alter an existing uORF. Dual-luciferase reporter assays showed significant reduction in protein translation, but no difference in the mRNA levels. Our study demonstrates, for the first time, the regulatory impact of uATG formation on EFNB1 levels and suggests that this should be the target region in molecular diagnosis of CFNS cases without pathogenic variants in the coding and splice sites regions of EFNB1.
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Affiliation(s)
- Vanessa L Romanelli Tavares
- Centro de Pesquisa sobre o Genoma Humano e Células-Tronco (CEGH-CEL), Curitiba, Brazil.,Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Curitiba, Brazil
| | - Erika Kague
- Centro de Pesquisa sobre o Genoma Humano e Células-Tronco (CEGH-CEL), Curitiba, Brazil.,Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Curitiba, Brazil.,Department of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol
| | - Camila M Musso
- Centro de Pesquisa sobre o Genoma Humano e Células-Tronco (CEGH-CEL), Curitiba, Brazil.,Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Curitiba, Brazil
| | - Thiago G P Alegria
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Curitiba, Brazil
| | - Renato S Freitas
- Centro de Atendimento Integral ao Fissurado Lábio Palatal (CAIF), Curitiba, Brazil.,Universidade Federal do Paraná, Curitiba, Brazil
| | - Debora R Bertola
- Centro de Pesquisa sobre o Genoma Humano e Células-Tronco (CEGH-CEL), Curitiba, Brazil.,Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Curitiba, Brazil.,Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo, São Paulo, Curitiba, Brazil
| | - Stephen R F Twigg
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Maria R Passos-Bueno
- Centro de Pesquisa sobre o Genoma Humano e Células-Tronco (CEGH-CEL), Curitiba, Brazil.,Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Curitiba, Brazil
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7
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Apostolopoulou D, Kaxira OS, Hatzaki A, Panagopoulos KP, Alexandrou K, Stratoudakis A, Kollia P, Aleporou V. Genetic Analysis of Syndromic and Nonsyndromic Patients With Craniosynostosis Identifies Novel Mutations in the TWIST1 and EFNB1 Genes. Cleft Palate Craniofac J 2018; 55:1092-1102. [PMID: 29561715 DOI: 10.1177/1055665618760412] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
INTRODUCTION Craniosynostosis, the premature fusion of cranial sutures, is usually divided into 2 major categories: syndromic and nonsyndromic. Mutations in the FGFR1, FGFR2, FGFR3, TWIST1, and EFNB1 genes cause the common craniosynostosis syndromes Muenke, Crouzon and Crouzon with acanthosis nigricans, Apert, Pfeiffer, Saethre-Chotzen, and Craniofrontonasal. Overlapping features among craniosynostosis syndromes, phenotypic heterogeneity even within the same syndrome, especially in the case of Muenke syndrome, and inadequate clinical evaluation can lead to misdiagnosis, which molecular testing can help clarify. OBJECTIVE The aim of this study is to investigate the underlying genetic cause in 46 patients with syndromic or nonsyndromic craniosynostosis by direct sequencing and/or microdeletion/microduplication analysis of the FGFR1-3, TWIST1, and EFNB1 genes. RESULTS Genetic analysis identified 3 novel mutations, c.413T>C - p.(Leu138Pro) [p.(L138P)] in TWIST1, the previously reported c.373G>A - p.(Glu125Lys) [p.(E125K)], and c.717dupA - p.(Leu240IlefsTer79) [p.(L240fs)] mutation in EFNB1 gene as well as 6 previously known mutations and a heterozygous TWIST1 gene deletion. The 2 novel mutations within EFNB1 gene arose de novo, but the novel mutation p.(L138P) within TWIST1 gene was inherited from the patient's father, who was found to be mosaic for the mutation. To our knowledge, this is the first case of mosaicism described for TWIST1 gene. CONCLUSIONS The contribution of molecular genetic analysis to the diagnosis of patients with syndromic craniosynostosis was useful because some were originally misdiagnosed. Conversely, thorough clinical evaluation can guide molecular testing and result in a correct diagnosis.
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Affiliation(s)
- Despina Apostolopoulou
- Department of Genetics and Biotechnology, School of Physical Sciences, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece.,AlfaLAB Molecular Biology and Cytogenetics Centre, Hygeia Group of Hospitals, Athens, Greece.,Hellenic Craniofacial Center, Athens, Greece
| | - Olga S Kaxira
- "MITERA" General, Maternity and Children Hospital, Athens, Greece
| | - Angeliki Hatzaki
- AlfaLAB Molecular Biology and Cytogenetics Centre, Hygeia Group of Hospitals, Athens, Greece
| | | | | | | | - Panagoula Kollia
- Department of Genetics and Biotechnology, School of Physical Sciences, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Vassiliki Aleporou
- Department of Genetics and Biotechnology, School of Physical Sciences, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
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8
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Taylor GM, Cooper GM, Losee JE, Mooney MP, Gilbert J. Molecular Analysis of Ephrin A4 and Ephrin B1 in a Rabbit Model of Craniosynostosis: Likely Exclusion as the Loci of Origin. Cleft Palate Craniofac J 2017; 55:1020-1025. [PMID: 28135115 DOI: 10.1597/16-135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Craniosynostosis (CS) has a prevalence of approximately 1 in every 2000 live births and is characterized by the premature fusion of one or more cranial sutures. Failure to maintain the cell lineage boundary at the coronal suture is thought to be involved in the pathology of some forms of CS. The Ephrin family of receptor tyrosine kinases consists of membrane-bound receptors and ligands that control cell patterning and the formation of developmental boundaries. Mutations in the ephrin A4 (EFNA4) and ephrin B1 (EFNB1) ligands have been linked to nonsyndromic CS and craniofrontonasal syndrome, respectively, in patient samples. We have previously described a colony of rabbits with a heritable pattern of coronal suture synostosis, although the genetic basis for synostosis within this model remains unknown. The present study was performed to determine if EFNA4 or EFNB1 could be the loci of the causal mutation in this unique animal model. Sequencing of EFNA4 and EFNB1 was performed using templates obtained from wild-type (n = 4) and craniosynostotic (n = 4) rabbits. No structural coding errors were identified in either gene. A single-nucleotide transversion was identified in one wild-type rabbit within the third intron of EFNA4. These data indicate that the causal locus for heritable CS in this rabbit model is not located within the structural coding regions of either EFNA4 or EFNB1.
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9
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Miller KA, Twigg SRF, McGowan SJ, Phipps JM, Fenwick AL, Johnson D, Wall SA, Noons P, Rees KEM, Tidey EA, Craft J, Taylor J, Taylor JC, Goos JAC, Swagemakers SMA, Mathijssen IMJ, van der Spek PJ, Lord H, Lester T, Abid N, Cilliers D, Hurst JA, Morton JEV, Sweeney E, Weber A, Wilson LC, Wilkie AOM. Diagnostic value of exome and whole genome sequencing in craniosynostosis. J Med Genet 2016; 54:260-268. [PMID: 27884935 PMCID: PMC5366069 DOI: 10.1136/jmedgenet-2016-104215] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 09/26/2016] [Accepted: 10/19/2016] [Indexed: 12/20/2022]
Abstract
Background Craniosynostosis, the premature fusion of one or more cranial sutures, occurs in ∼1 in 2250 births, either in isolation or as part of a syndrome. Mutations in at least 57 genes have been associated with craniosynostosis, but only a minority of these are included in routine laboratory genetic testing. Methods We used exome or whole genome sequencing to seek a genetic cause in a cohort of 40 subjects with craniosynostosis, selected by clinical or molecular geneticists as being high-priority cases, and in whom prior clinically driven genetic testing had been negative. Results We identified likely associated mutations in 15 patients (37.5%), involving 14 different genes. All genes were mutated in single families, except for IL11RA (two families). We classified the other positive diagnoses as follows: commonly mutated craniosynostosis genes with atypical presentation (EFNB1, TWIST1); other core craniosynostosis genes (CDC45, MSX2, ZIC1); genes for which mutations are only rarely associated with craniosynostosis (FBN1, HUWE1, KRAS, STAT3); and known disease genes for which a causal relationship with craniosynostosis is currently unknown (AHDC1, NTRK2). In two further families, likely novel disease genes are currently undergoing functional validation. In 5 of the 15 positive cases, the (previously unanticipated) molecular diagnosis had immediate, actionable consequences for either genetic or medical management (mutations in EFNB1, FBN1, KRAS, NTRK2, STAT3). Conclusions This substantial genetic heterogeneity, and the multiple actionable mutations identified, emphasises the benefits of exome/whole genome sequencing to identify causal mutations in craniosynostosis cases for which routine clinical testing has yielded negative results.
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Affiliation(s)
- Kerry A Miller
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Stephen R F Twigg
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Simon J McGowan
- Computational Biology Research Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Julie M Phipps
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.,Department of Clinical Genetics, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Aimée L Fenwick
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - David Johnson
- Craniofacial Unit, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Steven A Wall
- Craniofacial Unit, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Peter Noons
- Department of Craniofacial Surgery, Birmingham Children's Hospital NHS Foundation Trust, Birmingham, UK
| | - Katie E M Rees
- North East Thames Regional Genetics Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Elizabeth A Tidey
- North East Thames Regional Genetics Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Judith Craft
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - John Taylor
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jenny C Taylor
- Oxford Biomedical Research Centre, National Institute for Health Research, Oxford, UK.,Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Jacqueline A C Goos
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus Medical Centre, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - Sigrid M A Swagemakers
- Department of Bioinformatics, Erasmus Medical Centre, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - Irene M J Mathijssen
- Department of Plastic and Reconstructive Surgery and Hand Surgery, Erasmus Medical Centre, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - Peter J van der Spek
- Department of Bioinformatics, Erasmus Medical Centre, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - Helen Lord
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Tracy Lester
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Noina Abid
- Department of Paediatric Endocrinology, The Royal Belfast Hospital for Sick Children, Belfast, UK
| | - Deirdre Cilliers
- Department of Clinical Genetics, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.,Craniofacial Unit, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jane A Hurst
- North East Thames Regional Genetics Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Jenny E V Morton
- Clinical Genetics Unit, Birmingham Women's Hospital NHS Foundation Trust, Birmingham, UK
| | - Elizabeth Sweeney
- Department of Clinical Genetics, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Astrid Weber
- Department of Clinical Genetics, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Louise C Wilson
- North East Thames Regional Genetics Service, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Andrew O M Wilkie
- Clinical Genetics Group, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.,Department of Clinical Genetics, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.,Craniofacial Unit, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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10
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Yamamoto T, Igarashi N, Shimojima K, Sangu N, Sakamoto Y, Shimoji K, Niijima S. Use of targeted next-generation sequencing for molecular diagnosis of craniosynostosis: Identification of a novel de novo mutation of EFNB1. Congenit Anom (Kyoto) 2016. [PMID: 26208246 DOI: 10.1111/cga.12123] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Craniofrontonasal syndrome (CFNS; MIM#304110) is characterized by asymmetric facial features with hypertelorism and a broad bifid nose due to synostosis of the coronal suture. CFNS shows a unique X-linked inheritance pattern (most affected patients are female and obligate male carriers exhibit a mild manifestation or no typical features at all) associated with the ephrin-B1 gene (EFNB1) located in the Xq13.1 region. In this study, we performed targeted, massively parallel sequencing using a next-generation sequencer, and identified a novel EFNB1 mutation, c.270_271delCA, in a Japanese female patient with craniosynostosis. Because subsequent Sanger sequencing identified no mutation in either parent, this mutation was determined to be de novo in origin. After obtaining molecular diagnosis, a retrospective clinical evaluation confirmed the clinical diagnosis of CFNS in this patient. Comprehensive molecular diagnosis using a next-generation sequencer would be beneficial for early diagnosis of the patients with undiagnosed craniosynostosis.
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Affiliation(s)
- Toshiyuki Yamamoto
- Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan
| | - Naru Igarashi
- Department of Pediatrics, Juntendo University Nerima Hospital, Tokyo, Japan
| | - Keiko Shimojima
- Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan
| | - Noriko Sangu
- Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan
| | - Yuko Sakamoto
- Department of Orthopedics, Juntendo University Nerima Hospital, Tokyo, Japan
| | - Kazuaki Shimoji
- Department of Neurosurgery, Juntendo University, Tokyo, Japan
| | - Shinichi Niijima
- Department of Pediatrics, Juntendo University Nerima Hospital, Tokyo, Japan
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11
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Craniofrontonasal dysplasia: variability of the frontonasal suture and implications for treatment. J Craniofac Surg 2015; 24:1303-6. [PMID: 23851793 DOI: 10.1097/scs.0b013e3182942b5c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Craniofrontonasal dysplasia's (CFND's) phenotypic range includes hypertelorism, coronal craniosynostosis, frontonasal dysplasia, and digital anomalies. The variable expression is paradoxical for an X-linked syndrome because hemizygous males are less affected than heterozygous females. We describe a case of CFND due to a c.30>T EFNB1 gene mutation. In place of the typical craniosynostosis found in CFND, she presented with a superiorly displaced nasion and an anomalously positioned frontonasal suture. This report reveals an unreported malformation in CFND and its surgical implications.
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Mathijssen IMJ. Guideline for Care of Patients With the Diagnoses of Craniosynostosis: Working Group on Craniosynostosis. J Craniofac Surg 2015; 26:1735-807. [PMID: 26355968 PMCID: PMC4568904 DOI: 10.1097/scs.0000000000002016] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 06/28/2015] [Indexed: 01/15/2023] Open
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Phenotypes of craniofrontonasal syndrome in patients with a pathogenic mutation in EFNB1. Eur J Hum Genet 2013; 22:995-1001. [PMID: 24281372 DOI: 10.1038/ejhg.2013.273] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 10/15/2013] [Accepted: 10/24/2013] [Indexed: 11/08/2022] Open
Abstract
Craniofrontonasal syndrome (CFNS) is an X-linked developmental malformation, caused by mutations in the EFNB1 gene, which have only been described since 2004. A genotype-phenotype correlation seems not to be present. As it is of major importance to adequately counsel patients with EFNB1 mutations and their parents, and to improve diagnosis of new patients, more information about the phenotypic features is needed. This study included 23 patients (2 male, 21 female) with confirmed EFNB1 mutations. All patients underwent a thorough physical examination and photographs were taken. If available, radiological images were also consulted. Hypertelorism, longitudinal ridging and/or splitting of nails, a (mild) webbed neck and a clinodactyly of one or more toes were the only consistent features observed in all patients. Frequently observed phenotypic features were bifid tip of the nose (91%), columellar indentation (91%) and low implantation of breasts (90%). In comparison with anthropometric data of facial proportions, patients with CFNS had a significantly different face in multiple respects. An overview of all phenotypic features is shown. Patients with EFNB1 mutations have a clear phenotype. This study will facilitate genetic counseling of parents and patients, and contribute to the diagnostic and screening process of patients with suspected CFNS.
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Evers C, Jungwirth M, Morgenthaler J, Hinderhofer K, Maas B, Janssen J, Jauch A, Hehr U, Steinbeisser H, Moog U. Craniofrontonasal syndrome in a male due to chromosomal mosaicism involvingEFNB1: further insights into a genetic paradox. Clin Genet 2013; 85:347-53. [DOI: 10.1111/cge.12171] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/15/2013] [Accepted: 04/15/2013] [Indexed: 11/30/2022]
Affiliation(s)
- C. Evers
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - M.S. Jungwirth
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - J. Morgenthaler
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - K. Hinderhofer
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - B. Maas
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - J.W.G. Janssen
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - A. Jauch
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - U. Hehr
- Center for and Department of Human Genetics; University of Regensburg; Regensburg Germany
| | - H. Steinbeisser
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
| | - U. Moog
- Institute of Human Genetics; Heidelberg University; Heidelberg Germany
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A Novel De Novo EFNB1 Gene Mutation in a Mexican Patient with Craniofrontonasal Syndrome. Case Rep Genet 2013; 2013:349725. [PMID: 23509643 PMCID: PMC3594931 DOI: 10.1155/2013/349725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 12/30/2012] [Indexed: 11/22/2022] Open
Abstract
Craniofrontonasal syndrome (CNFS) is an X-linked disorder caused by mutations in the EFNB1 gene in which, paradoxically, heterozygous females are more severely affected than hemizygous males. In this paper, the clinical and molecular studies of a female subject with CFNS are described. A novel de novo c.473T>C (p.M158T) mutation in exon 3 of EFNB1 was demonstrated in this patient. The M158 residue of the Ephrin-B1 protein is highly conserved between species. Our results expand the mutational spectrum exposed by CNFS.
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Twigg SRF, Babbs C, van den Elzen MEP, Goriely A, Taylor S, McGowan SJ, Giannoulatou E, Lonie L, Ragoussis J, Sadighi Akha E, Knight SJL, Zechi-Ceide RM, Hoogeboom JAM, Pober BR, Toriello HV, Wall SA, Rita Passos-Bueno M, Brunner HG, Mathijssen IMJ, Wilkie AOM. Cellular interference in craniofrontonasal syndrome: males mosaic for mutations in the X-linked EFNB1 gene are more severely affected than true hemizygotes. Hum Mol Genet 2013; 22:1654-62. [PMID: 23335590 PMCID: PMC3605834 DOI: 10.1093/hmg/ddt015] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Craniofrontonasal syndrome (CFNS), an X-linked disorder caused by loss-of-function mutations of EFNB1, exhibits a paradoxical sex reversal in phenotypic severity: females characteristically have frontonasal dysplasia, craniosynostosis and additional minor malformations, but males are usually more mildly affected with hypertelorism as the only feature. X-inactivation is proposed to explain the more severe outcome in heterozygous females, as this leads to functional mosaicism for cells with differing expression of EPHRIN-B1, generating abnormal tissue boundaries—a process that cannot occur in hemizygous males. Apparently challenging this model, males occasionally present with a more severe female-like CFNS phenotype. We hypothesized that such individuals might be mosaic for EFNB1 mutations and investigated this possibility in multiple tissue samples from six sporadically presenting males. Using denaturing high performance liquid chromatography, massively parallel sequencing and multiplex-ligation-dependent probe amplification (MLPA) to increase sensitivity above standard dideoxy sequencing, we identified mosaic mutations of EFNB1 in all cases, comprising three missense changes, two gene deletions and a novel point mutation within the 5′ untranslated region (UTR). Quantification by Pyrosequencing and MLPA demonstrated levels of mutant cells between 15 and 69%. The 5′ UTR variant mutates the stop codon of a small upstream open reading frame that, using a dual-luciferase reporter construct, was demonstrated to exacerbate interference with translation of the wild-type protein. These results demonstrate a more severe outcome in mosaic than in constitutionally deficient males in an X-linked dominant disorder and provide further support for the cellular interference mechanism, normally related to X-inactivation in females.
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Affiliation(s)
- Stephen R F Twigg
- Clinical Genetics, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
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Senarath-Yapa K, Chung MT, McArdle A, Wong VW, Quarto N, Longaker MT, Wan DC. Craniosynostosis: molecular pathways and future pharmacologic therapy. Organogenesis 2012; 8:103-13. [PMID: 23249483 DOI: 10.4161/org.23307] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Craniosynostosis describes the premature fusion of one or more cranial sutures and can lead to dramatic manifestations in terms of appearance and functional impairment. Contemporary approaches for this condition are primarily surgical and are associated with considerable morbidity and mortality. The additional post-operative problems of suture refusion and bony relapse may also necessitate repeated surgeries with their own attendant risks. Therefore, a need exists to not only optimize current strategies but also to develop novel biological therapies which could obviate the need for surgery and potentially treat or even prevent premature suture fusion. Clinical studies of patients with syndromic craniosynostosis have provided some useful insights into the important signaling pathways and molecular events guiding suture fate. Furthermore, the highly conserved nature of craniofacial development between humans and other species have permitted more focused and step-wise elucidation of the molecular underpinnings of craniosynostosis. This review will describe the clinical manifestations of craniosynostosis, reflect on our understanding of syndromic and non-syndromic craniosynostoses and outline the different approaches that have been adopted in our laboratory and elsewhere to better understand the pathogenesis of premature suture fusion. Finally, we will assess to what extent our improved understanding of the pathogenesis of craniosynostosis, achieved through laboratory-based and clinical studies, have made the possibility of a non-surgical pharmacological approach both realistic and tangible.
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Affiliation(s)
- Kshemendra Senarath-Yapa
- Hagey Laboratory for Pediatric Regenerative Medicine; Department of Surgery; Stanford University School of Medicine; Stanford, CA USA
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Freitas ÉL, Gribble SM, Simioni M, Vieira TP, Prigmore E, Krepischi AC, Rosenberg C, Pearson PL, Melo DG, Gil-da-Silva-Lopes VL. A familial case with interstitial 2q36 deletion: variable phenotypic expression in full and mosaic state. Eur J Med Genet 2012; 55:660-5. [PMID: 22820457 DOI: 10.1016/j.ejmg.2012.06.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 06/09/2012] [Indexed: 11/24/2022]
Abstract
Submicroscopic chromosomal anomalies play an important role in the etiology of craniofacial malformations, including midline facial defects with hypertelorism (MFDH). MFDH is a common feature combination in several conditions, of which Frontonasal Dysplasia is the most frequently encountered manifestation; in most cases the etiology remains unknown. We identified a parent to child transmission of a 6.2 Mb interstitial deletion of chromosome region 2q36.1q36.3 by array-CGH and confirmed by FISH and microsatellite analysis. The patient and her mother both presented an MFDH phenotype although the phenotype in the mother was much milder than her daughter. Inspection of haplotype segregation within the family of 2q36.1 region suggests that the deletion arose on a chromosome derived from the maternal grandfather. Evidences based on FISH, microsatellite and array-CGH analysis point to a high frequency mosaicism for presence of a deleted region 2q36 occurring in blood of the mother. The frequency of mosaicism in other tissues could not be determined. We here suggest that the milder phenotype observed in the proband's mother can be explained by the mosaic state of the deletion. This most likely arose by an early embryonic deletion in the maternal embryo resulting in both gonadal and somatic mosaicism of two cell lines, with and without the deleted chromosome. The occurrence of gonadal mosaicism increases the recurrence risk significantly and is often either underestimated or not even taken into account in genetic counseling where new mutation is suspected.
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Affiliation(s)
- Érika L Freitas
- Department of Medical Genetics, Faculty of Medical Sciences, University of Campinas, Rua Tessália Vieira de Camargo, 126 CEP 13083-887 Campinas, São Paulo, Brazil
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Truitt L, Freywald A. Dancing with the dead: Eph receptors and their kinase-null partners. Biochem Cell Biol 2011; 89:115-29. [PMID: 21455264 DOI: 10.1139/o10-145] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Eph receptor tyrosine kinases and their ligands, ephrins, are membrane proteins coordinating a wide range of biological functions both in developing embryos and in adult multicellular organisms. Numerous studies have implicated Eph receptors in the induction of opposing responses, including cell adhesion or repulsion, support or inhibition of cell proliferation and cell migration, and progression or suppression of multiple malignancies. Similar to other receptor tyrosine kinases, Eph receptors rely on their ability to catalyze tyrosine phosphorylation for signal transduction. Interestingly, however, Eph receptors also actively utilize three kinase-deficient receptor tyrosine kinases, EphB6, EphA10, and Ryk, in their signaling network. The accumulating evidence suggests that the unusual flexibility of the Eph family, allowing it to initiate antagonistic responses, might be partially explained by the influence of the kinase-dead participants and that the exact outcome of an Eph-mediated action is likely to be defined by the balance between the signaling of catalytically potent and catalytically null receptors. We discuss in this minireview the emerging functions of the kinase-dead EphB6, EphA10, and Ryk receptors both in normal biological responses and in malignancy, and analyze currently available information related to the molecular mechanisms of their action in the context of the Eph family.
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Affiliation(s)
- Luke Truitt
- Department of Chemistry and Biochemistry, University of Regina, Sasketchewan, Canada
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Apostolopoulou D, Stratoudakis A, Hatzaki A, Kaxira OS, Panagopoulos KP, Kollia P, Aleporou V. A novel de novo mutation within EFNB1 gene in a young girl with craniofrontonasal syndrome. Cleft Palate Craniofac J 2011; 49:109-13. [PMID: 21385071 DOI: 10.1597/10-247] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Craniofrontonasal syndrome is mainly characterized by frontonasal dysplasia, telorbitism, a broad nasal root, and frequently a bifid nose and coronal craniosynostosis. Craniofrontonasal syndrome is an X-linked disorder with an unusual pattern of inheritance because heterozygous females are more severely affected than hemizygous males. The craniofrontonasal syndrome-causing gene is EFNB1, localized in the border region of chromosome Xq12 and Xq13.1, encoding for protein ephrin-B1. Here we aim to investigate the underlying genetic defect of a young girl with craniofrontonasal syndrome. The patient underwent surgical correction of her craniofacial deformities. Genetic analysis was carried out by polymerase chain reaction. Products of exon 2 of the EFNB1 gene were sequenced as well as digested with BpmI enzyme. A novel de novo missense mutation 373G>A was identified within the EFNB1 gene, leading to the replacement of glutamic acid at amino acid position 125 with lysine. The replacement of Glu125 with Lys, which lies within the G-H loop, part of the dimerization ligand-receptor interface, is expected to disrupt the interaction between the Eph receptor and ephrin B1 ligand, thus leading to craniofrontonasal syndrome.
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Affiliation(s)
- Despina Apostolopoulou
- Department of Genetics and Biotechnology, Faculty of Biology, School of Physical Sciences, National and Kapodistrian University of Athens, Panepistimioupolis, GR-157 01, Athens, Greece.
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Hogue J, Shankar S, Perry H, Patel R, Vargervik K, Slavotinek A. A novel EFNB1 mutation (c.712delG) in a family with craniofrontonasal syndrome and diaphragmatic hernia. Am J Med Genet A 2010; 152A:2574-7. [PMID: 20734337 DOI: 10.1002/ajmg.a.33596] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We report on the occurrence of congenital diaphragmatic hernia in a family with craniofrontonasal syndrome found to have a previously unreported mutation in EFNB1. The female proband presented with hypertelorism, telecanthus, bifid nasal tip, widow's peak, frontal bossing, and a widened metopic suture. Her father was noted to have hypertelorism, telecanthus, widow's peak, and a history of pectus carinatum. He was found to have a previously unreported mutation in exon 5 of EFNB1 predicted to cause premature protein truncation. The parents of the proband previously had a female fetus with congenital diaphragmatic hernia. The occurrence of congenital diaphragmatic hernia, phenotypic differences between males and females, and utility of molecular testing in craniofrontonasal syndrome are demonstrated.
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Affiliation(s)
- Jacob Hogue
- Department of Pediatrics, University of California, San Francisco, California 94143-0706, USA.
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Makarov R, Steiner B, Gucev Z, Tasic V, Wieacker P, Wieland I. The impact of CFNS-causing EFNB1 mutations on ephrin-B1 function. BMC MEDICAL GENETICS 2010; 11:98. [PMID: 20565770 PMCID: PMC2901216 DOI: 10.1186/1471-2350-11-98] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 06/17/2010] [Indexed: 02/02/2023]
Abstract
Background Mutations of EFNB1 cause the X-linked malformation syndrome craniofrontonasal syndrome (CFNS). CFNS is characterized by an unusual phenotypic pattern of inheritance, because it affects heterozygous females more severely than hemizygous males. This sex-dependent inheritance has been explained by random X-inactivation in heterozygous females and the consequences of cellular interference of wild type and mutant EFNB1-expressing cell populations. EFNB1 encodes the transmembrane protein ephrin-B1, that forms bi-directional signalling complexes with Eph receptor tyrosine kinases expressed on complementary cells. Here, we studied the effects of patient-derived EFNB1 mutations predicted to give rise to truncated ephrin-B1 protein or to disturb Eph/ephrin-B1 reverse ephrin-B1 signalling. Five mutations are investigated in this work: nonsense mutation c.196C > T/p.R66X, frameshift mutation c.614_615delCT, splice-site mutation c.406 + 2T > C and two missense mutations p.P54L and p.T111I. Both missense mutations are located in the extracellular ephrin domain involved in Eph-ephrin-B1 recognition and higher order complex formation. Methods Nonsense mutation c.196C > T/p.R66X, frameshift mutation c.614_615delCT and splice-site mutation c.406+2T > C were detected in the primary patient fibroblasts by direct sequencing of the DNA and were further analysed by RT-PCR and Western blot analyses. The impact of missense mutations p.P54L and p.T111I on cell behaviour and reverse ephrin-B1 cell signalling was analysed in a cell culture model using NIH 3T3 fibroblasts. These cells were transfected with the constructs generated by in vitro site-directed mutagenesis. Investigation of missense mutations was performed using the Western blot analysis and time-lapse microscopy. Results and Discussion Nonsense mutation c.196C > T/p.R66X and frameshift mutation c.614_615delCT escape nonsense-mediated RNA decay (NMD), splice-site mutation c.406+2T > C results in either retention of intron 2 or activation of a cryptic splice site in exon 2. However, c.614_615delCT and c.406+2T > C mutations were found to be not compatible with production of a soluble ephrin-B1 protein. Protein expression of the p.R66X mutation was predicted unlikely but has not been investigated. Ectopic expression of p.P54L ephrin-B1 resists Eph-receptor mediated cell cluster formation in tissue culture and intracellular ephrin-B1 Tyr324 and Tyr329 phosphorylation. Cells expressing p.T111I protein show similar responses as wild type expressing cells, however, phosphorylation of Tyr324 and Tyr329 is reduced. Conclusions Pathogenic mechanisms in CFNS manifestation include impaired ephrin-B1 signalling combined with cellular interference.
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Affiliation(s)
- Roman Makarov
- Institut für Humangenetik, Universitätsklinikum, Otto-von-Guericke-Universität, Magdeburg, Germany
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