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Vos GM, Wu Y, van der Woude R, de Vries RP, Boons GJ. Chemo-Enzymatic Synthesis of Isomeric I-branched Polylactosamines Using Traceless Blocking Groups. Chemistry 2024; 30:e202302877. [PMID: 37909475 DOI: 10.1002/chem.202302877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/03/2023]
Abstract
Poly-N-acetyl lactosamines (polyLacNAc) are common structural motifs of N- and O-linked glycan, glycosphingolipids and human milk oligosaccharides. They can be branched by the addition of β1,6-linked N-acetyl-glucosamine (GlcNAc) moieties to internal galactoside (Gal) residues by the I-branching enzyme beta-1,6-N-acetylglucosaminyltransferase 2 (GCNT2). I-branching has been implicated in many biological processes and is also associated with various diseases such as cancer progression. Currently, there is a lack of methods that can install, in a regioselective manner, I-branches and allows the preparation of isomeric poly-LacNAc derivatives. Here, we described a chemo-enzymatic strategy that addresses this deficiency and is based on the enzymatic assembly of an oligo-LacNAc chain that at specific positions is modified by a GlcNTFA moiety. Replacement of the trifluoroacetyl (TFA) moiety by tert-butyloxycarbonyl (Boc) gives compounds in which the galactoside at the proximal site is blocked from modification by GCNT2. After elaboration of the antennae, the Boc group can be removed, and the resulting amine acetylated to give natural I-branched structures. It is also shown that fucosides can function as a traceless blocking group that can provide complementary I-branched structures from a single precursor. The methodology made it possible to synthesize a library of polyLacNAc chains having various topologies.
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Affiliation(s)
- Gaёl M Vos
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG, Utrecht, Netherlands
| | - Yunfei Wu
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG, Utrecht, Netherlands
| | - Roosmarijn van der Woude
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG, Utrecht, Netherlands
| | - Robert P de Vries
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG, Utrecht, Netherlands
| | - Geert-Jan Boons
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG, Utrecht, Netherlands
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA-30602, USA
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
- Chemistry Department, University of Georgia, Athens, GA-30602, USA
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Türkyılmaz A, Kaplan AT, Öskan Yalçın S, Sağer SG, Şimşek Ş. Identification of novel variants in Turkish families with non-syndromic congenital cataracts using whole-exome sequencing. Int Ophthalmol 2023; 43:4573-4583. [PMID: 37592116 DOI: 10.1007/s10792-023-02857-1] [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: 11/11/2021] [Accepted: 08/05/2023] [Indexed: 08/19/2023]
Abstract
PURPOSE The present study aimed to identify the molecular etiology of non-syndromic congenital cataract (CC) using whole-exome sequencing (WES) analysis. METHODS In the present study, ophthalmologic results and pedigree analysis of the families of 12 patients with non-syndromic CC were evaluated. WES analysis was conducted after DNA was isolated from peripheral blood samples obtained from the patients. RESULTS Twelve non-syndromic probands (10 males and 2 females) with bilateral CC were included in the study. Patient age ranged between 1 and 11 months. WES analysis showed pathogenic/likely pathogenic variant in 7 (58%) of the 12 families and variant of unknown significance (VUS) in 5 (42%) of them. All the 13 different variants detected in 9 different CC-related genes were co-segregated with the disease. Autosomal dominant inheritance was found in 7 (58%) of the families and autosomal recessive inheritance was found in 5 (42%) of them. CONCLUSION To the best of our knowledge, the present research is one of the limited numbers of studies in the Turkish population in which genetically heterogeneous non-syndromic CC was investigated using WES analysis. Novel variants that we identified in DNMBP, LSS, and WFS1 genes, which are rarely associated with the CC phenotype, have contributed to the mutation spectrum of this disease. Identifying the relevant molecular genetic etiology allows accurate genetic counseling to be provided to the families.
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Affiliation(s)
- Ayberk Türkyılmaz
- Department of Medical Genetics, Faculty of Medicine, Karadeniz Technical University, Ortahisar, Trabzon, Turkey.
| | - Ayşin Tuba Kaplan
- Department of Ophthalmology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
| | - Sibel Öskan Yalçın
- Department of Ophthalmology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
| | - Safiye Güneş Sağer
- Department of Pediatric Neurology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
| | - Şaban Şimşek
- Department of Ophthalmology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
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3
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Perez M, Chakraborty A, Lau LS, Mohammed NBB, Dimitroff CJ. Melanoma-associated glycosyltransferase GCNT2 as an emerging biomarker and therapeutic target. Br J Dermatol 2021; 185:294-301. [PMID: 33660254 DOI: 10.1111/bjd.19891] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2021] [Indexed: 12/17/2022]
Abstract
In metastatic melanoma, with a dismal survival rate and propensity for treatment resistance and recurrence, it is critical to establish biomarkers that better predict treatment response and disease severity. The melanoma glycome, composed of complex carbohydrates termed glycans, is an under-investigated area of research, although it is gaining momentum in the cancer biomarker and therapeutics field. Novel findings suggest that glycans play a major role in influencing melanoma progression and could be exploited for prognosticating metastatic activity and/or as therapeutic targets. In this review, we discuss the role of aberrant glycosylation, particularly the specialized function of β1,6 N-acetylglucosaminyltransferase 2 (GCNT2), in melanoma pathogenesis and summarize mechanisms of GCNT2 regulation to illuminate its potential as a predictive marker and therapeutic target.
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Affiliation(s)
- M Perez
- Department of Translational Medicine, Translational Glycobiology Institute at FIU, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - A Chakraborty
- Department of Translational Medicine, Translational Glycobiology Institute at FIU, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - L S Lau
- Department of Translational Medicine, Translational Glycobiology Institute at FIU, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - N B B Mohammed
- Department of Translational Medicine, Translational Glycobiology Institute at FIU, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - C J Dimitroff
- Department of Translational Medicine, Translational Glycobiology Institute at FIU, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
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4
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Molecular genetics of congenital cataracts. Exp Eye Res 2019; 191:107872. [PMID: 31770519 DOI: 10.1016/j.exer.2019.107872] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 12/18/2022]
Abstract
Congenital cataracts, the most common cause of visual impairment and blindness in children worldwide, have diverse etiologies. According to statistics analysis, about one quarter of congenital cataracts caused by genetic defects. Various mutations of more than one hundred genes have been identified in hereditary cataracts so far. In this review, we briefly summarize recent developments about the genetics, molecular mechanisms, and treatments of congenital cataracts. The studies of these pathogenic mutations and molecular genetics is making it possible for us to comprehend the underlying mechanisms of cataractogenesis and providing new insights into the preventive, diagnostic and therapeutic approaches of cataracts.
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Li J, Leng Y, Han S, Yan L, Lu C, Luo Y, Zhang X, Cao L. Clinical and genetic characteristics of Chinese patients with familial or sporadic pediatric cataract. Orphanet J Rare Dis 2018; 13:94. [PMID: 29914532 PMCID: PMC6006596 DOI: 10.1186/s13023-018-0828-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/18/2018] [Indexed: 12/11/2022] Open
Abstract
Background Pediatric cataract is a clinically and genetically heterogeneous disease which is a significant cause of lifelong visual impairment and treatable blindness. Our study aims to investigate the genotype spectrum in a group of Chinese patients with pediatric cataract. Methods We enrolled 39 families with pediatric cataract from October 2015 to April 2016. DNA samples of the probands were analyzed by target next-generation sequencing. Variants were validated using Sanger sequencing in the probands and available family members. Results In our cohort of 39 cases with different types of pediatric cataract, 23 cases were found to harbor putative pathogenic variants in 15 genes: CRYAA, CRYBA1, CRYBA4, CRYBB1, CRYGC, CRYGD, MIP, GCNT2, IARS2, NHS, BCOR, BFSP2, FYCO1, MAF, and PAX6. The mutation detection rates in the familial and sporadic cases were 75 and 47.8%, respectively. Of the 23 causative variants, over half were novel. Conclusions This is a rare report of systematic mutation screening analysis of pediatric cataract in a comparably large cohort of Chinese patients. Our observations enrich the mutation spectrum of pediatric cataract. Next-generation sequencing provides significant diagnostic information for pediatric cataract cases, especially when considering sporadic and subtle syndromal cases. Electronic supplementary material The online version of this article (10.1186/s13023-018-0828-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jingyan Li
- The Research Center for Medical Genomics, Key Laboratory of Cell Biology, Ministry of Public Health, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China
| | - Yunji Leng
- The Research Center for Medical Genomics, Key Laboratory of Cell Biology, Ministry of Public Health, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China
| | - Shirui Han
- The Research Center for Medical Genomics, Key Laboratory of Cell Biology, Ministry of Public Health, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China
| | - Lulu Yan
- The Research Center for Medical Genomics, Key Laboratory of Cell Biology, Ministry of Public Health, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China
| | - Chaoxia Lu
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100005, China
| | - Yang Luo
- The Research Center for Medical Genomics, Key Laboratory of Cell Biology, Ministry of Public Health, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China
| | - Xue Zhang
- The Research Center for Medical Genomics, Key Laboratory of Cell Biology, Ministry of Public Health, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China. .,McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100005, China.
| | - Lihua Cao
- The Research Center for Medical Genomics, Key Laboratory of Cell Biology, Ministry of Public Health, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, China.
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Magwebu ZE, Abdul-Rasool S, Seier JV, Chauke CG. Autosomal recessive congenital cataract in captive-bred vervet monkeys (Chlorocebus aethiops). J Med Primatol 2018; 47:93-100. [DOI: 10.1111/jmp.12332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/01/2018] [Indexed: 11/29/2022]
Affiliation(s)
- Zandisiwe E. Magwebu
- Primate Unit and Delft Animal Centre (PUDAC); South African Medical Research Council (SAMRC); Tygerberg Cape Town South Africa
- Medical Bioscience Department; University of the Western Cape; Belville South Africa
| | - Sahar Abdul-Rasool
- Medical Bioscience Department; University of the Western Cape; Belville South Africa
| | - Jürgen V. Seier
- Primate Unit and Delft Animal Centre (PUDAC); South African Medical Research Council (SAMRC); Tygerberg Cape Town South Africa
| | - Chesa G. Chauke
- Primate Unit and Delft Animal Centre (PUDAC); South African Medical Research Council (SAMRC); Tygerberg Cape Town South Africa
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Srivastava K, Stiles DA, Wagner FF, Flegel WA. Two large deletions extending beyond either end of the RHD gene and their red cell phenotypes. J Hum Genet 2018; 63:27-35. [PMID: 29215093 PMCID: PMC5764804 DOI: 10.1038/s10038-017-0345-3] [Citation(s) in RCA: 6] [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: 06/09/2017] [Revised: 08/12/2017] [Accepted: 08/14/2017] [Indexed: 01/22/2023]
Abstract
Only two partial deletions longer than 655 nucleotides had been reported for the RHD gene, constrained within the gene and causing DEL phenotypes. Using a combination of quantitative PCR and long-range PCR, we examined three distinct deletions affecting parts of the RHD gene in three blood donors. Their RHD nucleotide sequences and exact boundaries of the breakpoint regions were determined. DEL phenotypes were caused by a novel 18.4 kb deletion and a previously published 5.4 kb deletion of the RHD gene; a D-negative phenotype was caused by a novel 7.6 kb deletion. Examination of the deletion-flanking regions suggested microhomology-mediated end-joining, replication slippage, and non-homologous end-joining, respectively, as the most likely mechanisms for the three distinct deletions. We described two new deletions affecting parts of the RHD gene, much longer than any previously reported partial deletion: one was the first deletion observed at the 5' end of the RHD gene extending into the intergenic region, and the other the second deletion observed at its 3' end. Large deletions present at either end are a mechanism for a much reduced RhD protein expression or its complete loss. Exact molecular characterization of such deletions is instrumental for accurate RHD genotyping.
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Affiliation(s)
- Kshitij Srivastava
- Department of Transfusion Medicine, Clinical Center, National Institutes of Health, MSC 1184, 10 Center Drive, Bethesda, 20892, MD, USA
| | - David Alan Stiles
- Department of Transfusion Medicine, Clinical Center, National Institutes of Health, MSC 1184, 10 Center Drive, Bethesda, 20892, MD, USA
| | - Franz Friedrich Wagner
- Red Cross Blood Service NSTOB, Institute Springe, Eldagsener Strasse 38, 31830, Springe, Germany
| | - Willy Albert Flegel
- Department of Transfusion Medicine, Clinical Center, National Institutes of Health, MSC 1184, 10 Center Drive, Bethesda, 20892, MD, USA.
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Javadiyan S, Craig JE, Souzeau E, Sharma S, Lower KM, Mackey DA, Staffieri SE, Elder JE, Taranath D, Straga T, Black J, Pater J, Casey T, Hewitt AW, Burdon KP. High-Throughput Genetic Screening of 51 Pediatric Cataract Genes Identifies Causative Mutations in Inherited Pediatric Cataract in South Eastern Australia. G3 (BETHESDA, MD.) 2017; 7:3257-3268. [PMID: 28839118 PMCID: PMC5633377 DOI: 10.1534/g3.117.300109] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 08/15/2017] [Indexed: 01/09/2023]
Abstract
Pediatric cataract is a leading cause of childhood blindness. This study aimed to determine the genetic cause of pediatric cataract in Australian families by screening known disease-associated genes using massively parallel sequencing technology. We sequenced 51 previously reported pediatric cataract genes in 33 affected individuals with a family history (cases with previously known or published mutations were excluded) using the Ion Torrent Personal Genome Machine. Variants were prioritized for validation if they were predicted to alter the protein sequence and were absent or rare with minor allele frequency <1% in public databases. Confirmed mutations were assessed for segregation with the phenotype in all available family members. All identified novel or previously reported cataract-causing mutations were screened in 326 unrelated Australian controls. We detected 11 novel mutations in GJA3, GJA8, CRYAA, CRYBB2, CRYGS, CRYGA, GCNT2, CRYGA, and MIP; and three previously reported cataract-causing mutations in GJA8, CRYAA, and CRYBB2 The most commonly mutated genes were those coding for gap junctions and crystallin proteins. Including previous reports of pediatric cataract-associated mutations in our Australian cohort, known genes account for >60% of familial pediatric cataract in Australia, indicating that still more causative genes remain to be identified.
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Affiliation(s)
- Shari Javadiyan
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Jamie E Craig
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Emmanuelle Souzeau
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Shiwani Sharma
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Karen M Lower
- Department of Haematology and Genetic Pathology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - David A Mackey
- Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, Western Australia 6009, Australia
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria 3002, Australia
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
| | - Sandra E Staffieri
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria 3002, Australia
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
- Department of Ophthalmology, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - James E Elder
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
- Department of Ophthalmology, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - Deepa Taranath
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
| | - Tania Straga
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - Joanna Black
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - John Pater
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - Theresa Casey
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
| | - Alex W Hewitt
- Department of Surgery, University of Melbourne, Victoria 3010, Australia
- Ophthalmology Department, Women's and Children's Hospital, Adelaide, South Australia 5006, Australia
- Department of Paediatrics, University of Melbourne, Victoria 3010, Australia
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Kathryn P Burdon
- Department of Ophthalmology, School of Medicine, Flinders University, Adelaide, South Australia 5042, Australia
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
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Cheong SS, Hull S, Jones B, Chana R, Thornton N, Plagnol V, Moore AT, Hardcastle AJ. Pleiotropic effect of a novel mutation in GCNT2 causing congenital cataract and a rare adult i blood group phenotype. Hum Genome Var 2017; 4:17004. [PMID: 28224043 PMCID: PMC5311056 DOI: 10.1038/hgv.2017.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 11/09/2022] Open
Abstract
Mutations in GCNT2 have been associated with the rare adult i blood group phenotype with or without congenital cataract. We report a novel homozygous frameshift mutation c.1163_1166delATCA, p.(Asn388Argfs*20) as the cause of congenital cataract in two affected siblings. Blood group typing confirmed that both affected males have the rare adult i phenotype, supporting the hypothesis that the partial association of I/i phenotype and congenital cataract is due to the differential expression of GCNT2 isoforms.
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Affiliation(s)
| | | | - Benjamin Jones
- IBGRL Red Cell Reference Laboratory, NHS Blood and Transplant , Bristol, UK
| | | | - Nicole Thornton
- IBGRL Red Cell Reference Laboratory, NHS Blood and Transplant , Bristol, UK
| | | | - Anthony T Moore
- UCL Institute of Ophthalmology, London, UK; Moorfields Eye Hospital, London, UK; Ophthalmology Department, UCSF School of Medicine, San Francisco, CA, USA
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Messina-Baas O, Cuevas-Covarrubias SA. Inherited Congenital Cataract: A Guide to Suspect the Genetic Etiology in the Cataract Genesis. Mol Syndromol 2017; 8:58-78. [PMID: 28611546 DOI: 10.1159/000455752] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2016] [Indexed: 01/23/2023] Open
Abstract
Cataracts are the principal cause of treatable blindness worldwide. Inherited congenital cataract (CC) shows all types of inheritance patterns in a syndromic and nonsyndromic form. There are more than 100 genes associated with cataract with a predominance of autosomal dominant inheritance. A cataract is defined as an opacity of the lens producing a variation of the refractive index of the lens. This variation derives from modifications in the lens structure resulting in light scattering, frequently a consequence of a significant concentration of high-molecular-weight protein aggregates. The aim of this review is to introduce a guide to identify the gene involved in inherited CC. Due to the manifold clinical and genetic heterogeneity, we discarded the cataract phenotype as a cardinal sign; a 4-group classification with the genes implicated in inherited CC is proposed. We consider that this classification will assist in identifying the probable gene involved in inherited CC.
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Irum B, Khan SY, Ali M, Daud M, Kabir F, Rauf B, Fatima F, Iqbal H, Khan AO, Al Obaisi S, Naeem MA, Nasir IA, Khan SN, Husnain T, Riazuddin S, Akram J, Eghrari AO, Riazuddin SA. Deletion at the GCNT2 Locus Causes Autosomal Recessive Congenital Cataracts. PLoS One 2016; 11:e0167562. [PMID: 27936067 PMCID: PMC5147899 DOI: 10.1371/journal.pone.0167562] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 11/16/2016] [Indexed: 11/25/2022] Open
Abstract
PURPOSE The aim of this study is to identify the molecular basis of autosomal recessive congenital cataracts (arCC) in a large consanguineous pedigree. METHODS All participating individuals underwent a detailed ophthalmic examination. Each patient's medical history, particularly of cataracts and other ocular abnormalities, was compiled from available medical records and interviews with family elders. Blood samples were donated by all participating family members and used to extract genomic DNA. Genetic analysis was performed to rule out linkage to known arCC loci and genes. Whole-exome sequencing libraries were prepared and paired-end sequenced. A large deletion was found that segregated with arCC in the family, and chromosome walking was conducted to estimate the proximal and distal boundaries of the deletion mutation. RESULTS Exclusion and linkage analysis suggested linkage to a region of chromosome 6p24 harboring GCNT2 (glucosaminyl (N-acetyl) transferase 2) with a two-point logarithm of odds score of 5.78. PCR amplifications of the coding exons of GCNT2 failed in individuals with arCC, and whole-exome data analysis revealed a large deletion on chromosome 6p in the region harboring GCNT2. Chromosomal walking using multiple primer pairs delineated the extent of the deletion to approximately 190 kb. Interestingly, a failure to amplify a junctional fragment of the deletion break strongly suggests an insertion in addition to the large deletion. CONCLUSION Here, we report a novel insertion/deletion mutation at the GCNT2 locus that is responsible for congenital cataracts in a large consanguineous family.
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Affiliation(s)
- Bushra Irum
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shahid Y. Khan
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Muhammad Ali
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Muhammad Daud
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Bushra Rauf
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Fareeha Fatima
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Hira Iqbal
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Arif O. Khan
- King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Saif Al Obaisi
- King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Idrees A. Nasir
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Tayyab Husnain
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
- National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
- National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Allen O. Eghrari
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
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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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Kitada K, Aikawa S, Aida S. Alu-Alu fusion sequences identified at junction sites of copy number amplified regions in cancer cell lines. Cytogenet Genome Res 2012; 139:1-8. [PMID: 22986581 DOI: 10.1159/000342885] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2012] [Indexed: 12/13/2022] Open
Abstract
Alu elements are short, ∼300-bp stretches of DNA and are the most abundant repetitive elements in the human genome. A large number of chromosomal rearrangements mediated by Alu-Alu recombination have been reported in germline cells, but only a few in somatic cells. Cancer development is frequently accompanied by various chromosomal rearrangements including gene amplification. To explore an involvement of Alu-Alu fusion in gene amplification events, we determined 20 junction site sequences of 5 highly amplified regions in 4 cancer cell lines. The amplified regions exhibited a common copy number profile: a stair-like increase with multiple segments, which is implicated in the breakage-fusion-bridge (BFB) cycle-mediated amplification. All of the sequences determined were characterized as head-to-head or tail-to-tail fusion of sequences separated by 1-5 kb in the genome sequence. Of these, 4 junction site sequences were identified as Alu-Alu fusions between inverted, paired Alu elements with relatively long overlapping sequences of 17, 21, 22, and 24 bp. Together with genome mapping data of Alu elements, these findings suggest that when breakages occur at or near inverted, paired Alu elements in the process of BFB cycle-mediated amplification, sequence homology of Alu elements is frequently used to repair the broken ends.
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Affiliation(s)
- K Kitada
- Kamakura Research Laboratories, Chugai Pharmaceutical Co. Ltd., Kamakura, Japan.
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Aldahmesh MA, Khan AO, Mohamed JY, Hijazi H, Al-Owain M, Alswaid A, Alkuraya FS. Genomic analysis of pediatric cataract in Saudi Arabia reveals novel candidate disease genes. Genet Med 2012; 14:955-62. [PMID: 22935719 DOI: 10.1038/gim.2012.86] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Pediatric cataract is an important preventable blinding disease. Previous studies have estimated 10-25% of cases to be genetic in etiology. METHODS In an effort to characterize the genetics of cataract in our population, we have conducted a comprehensive clinical and genomic analysis (including autozygome and exome analysis) on a series of 38 index patients. RESULTS Pediatric cataract is genetic in at least 79% of the study families. Although crystallins accounted for most of the mutant alleles, mutations in other genes were encountered, including recessive mutations in genes that usually cause the disease in a dominant manner. In addition, several novel candidate genes (MFSD6L, AKR1E2, RNLS, and CYP51A1) were identified. CONCLUSION Pediatric cataract is typically a genetic disease, usually autosomal recessive, in Saudi Arabia. Although defining a specific cataract phenotype can sometimes predict the genetic cause, genomic analysis is often required to unravel the causative mutation given the marked genetic heterogeneity. The identified novel candidate genes require independent confirmation in future studies.
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Affiliation(s)
- Mohammed A Aldahmesh
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
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