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Elert-Dobkowska E, Stepniak I, Radziwonik-Fraczyk W, Jahic A, Beetz C, Sulek A. SPAST Intragenic CNVs Lead to Hereditary Spastic Paraplegia via a Haploinsufficiency Mechanism. Int J Mol Sci 2024; 25:5008. [PMID: 38732227 PMCID: PMC11084448 DOI: 10.3390/ijms25095008] [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: 02/29/2024] [Revised: 04/26/2024] [Accepted: 04/30/2024] [Indexed: 05/13/2024] Open
Abstract
The most common form of hereditary spastic paraplegia (HSP), SPG4 is caused by single nucleotide variants and microrearrangements in the SPAST gene. The high percentage of multi-exonic deletions or duplications observed in SPG4 patients is predisposed by the presence of a high frequency of Alu sequences in the gene sequence. In the present study, we analyzed DNA and RNA samples collected from patients with different microrearrangements in SPAST to map gene breakpoints and evaluate the mutation mechanism. The study group consisted of 69 individuals, including 50 SPG4 patients and 19 healthy relatives from 18 families. Affected family members from 17 families carried varying ranges of microrearrangements in the SPAST gene, while one individual had a single nucleotide variant in the 5'UTR of SPAST. To detect the breakpoints of the SPAST gene, long-range PCR followed by sequencing was performed. The breakpoint sequence was detected for five different intragenic SPAST deletions and one duplication, revealing Alu-mediated microhomology at breakpoint junctions resulting from non-allelic homologous recombination in these patients. Furthermore, SPAST gene expression analysis was performed using patient RNA samples extracted from whole blood. Quantitative real-time PCR tests performed in 14 patients suggest no expression of transcripts with microrearrangements in 5 of them. The obtained data indicate that nonsense-mediated decay degradation is not the only mechanism of hereditary spastic paraplegia in patients with SPAST microrearrangements.
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Affiliation(s)
- Ewelina Elert-Dobkowska
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland; (E.E.-D.); (I.S.); (W.R.-F.)
| | - Iwona Stepniak
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland; (E.E.-D.); (I.S.); (W.R.-F.)
| | - Wiktoria Radziwonik-Fraczyk
- Department of Genetics, Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland; (E.E.-D.); (I.S.); (W.R.-F.)
| | - Amir Jahic
- Institute of Diagnostic Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité–Universitätsmedizin, 10117 Berlin, Germany;
| | - Christian Beetz
- Department of Chemistry and Laboratory Medicine, Jena University Hospital, 07747 Jena, Germany;
- Centogene, 18055 Rostock, Germany
| | - Anna Sulek
- Faculty of Medicine, Lazarski University, 02-662 Warsaw, Poland
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2
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Ghasemi A, Sadr Z, Babanejad M, Rohani M, Alavi A. Copy Number Variations in Hereditary Spastic Paraplegia-Related Genes: Evaluation of an Iranian Hereditary Spastic Paraplegia Cohort and Literature Review. Mol Syndromol 2023; 14:477-484. [PMID: 38058755 PMCID: PMC10697729 DOI: 10.1159/000531507] [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: 05/11/2023] [Accepted: 06/07/2023] [Indexed: 12/08/2023] Open
Abstract
Introduction In human genetic disorders, copy number variations (CNVs) are considered a considerable underlying cause. CNVs are generally detected by array-based methods but can also be discovered by read-depth analysis of whole-exome sequencing (WES) data. We performed WES-based CNV identification in a cohort of 35 Iranian families with hereditary spastic paraplegia (HSP) patients. Methods Thirty-five patients whose routine single-nucleotide variants (SNVs) and insertion/deletion analyses from exome data were unrevealing underwent a pipeline of CNV analysis using the read-depth detection method. Subsequently, a comprehensive search about the existence of CNVs in all 84 known HSP-causing genes was carried out in all reported HSP cases, so far. Results and Discussion CNV analysis of exome data indicated that 1 patient harbored a heterozygous deletion in exon 17 of the SPAST gene. Multiplex ligation-dependent probe amplification analysis confirmed this deletion in the proband and his affected father. Literature review demonstrated that, to date, pathogenic CNVs have been identified in 30 out of 84 HSP-causing genes (∼36%). However, CNVs in only 17 of these genes were specifically associated with the HSP phenotype. Among them, CNVs were more common in L1CAM, PLP1, SPAST, SPG7, SPG11, and REEP1 genes. The identification of the CNV in 1 of our patients suggests that WES allows the detection of both SNVs and CNVs from a single method without additional costs and execution time. However, because of intrinsic issues of WES in the detection of large rearrangements, it may not yet be exploited to replace the CNV detection methods in standard clinical practice.
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Affiliation(s)
- Aida Ghasemi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Zahra Sadr
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mojgan Babanejad
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mohammad Rohani
- Department of Neurology, Iran University of Medical Sciences, Hazrat Rasool Hospital, Tehran, Iran
| | - Afagh Alavi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
- Neuromuscular Research Center, Tehran University of Medical Sciences, Tehran, Iran
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Chen YJ, Wang MW, Qiu YS, Yuan RY, Wang N, Lin X, Chen WJ. Alu Retrotransposition Event in SPAST Gene as a Novel Cause of Hereditary Spastic Paraplegia. Mov Disord 2023; 38:1750-1755. [PMID: 37394769 DOI: 10.1002/mds.29522] [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: 01/31/2023] [Revised: 06/05/2023] [Accepted: 06/12/2023] [Indexed: 07/04/2023] Open
Abstract
OBJECTIVES To diagnose the molecular cause of hereditary spastic paraplegia (HSP) observed in a four-generation family with autosomal dominant inheritance. METHODS Multiplex ligation-dependent probe amplification (MLPA), whole-exome sequencing (WES), and RNA sequencing (RNA-seq) of peripheral blood leukocytes were performed. Reverse transcription polymerase chain reaction (RT-PCR) and Sanger sequencing were used to characterize target regions of SPAST. RESULTS A 121-bp AluYb9 insertion with a 30-bp poly-A tail flanked by 15-bp direct repeats on both sides was identified in the edge of intron 16 in SPAST that segregated with the disease phenotype. CONCLUSIONS We identified an intronic AluYb9 insertion inducing splicing alteration in SPAST causing pure HSP phenotype that was not detected by routine WES analysis. Our findings suggest RNA-seq is a recommended implementation for undiagnosed cases by first-line diagnostic approaches. © 2023 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Yi-Jun Chen
- Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- Department of Geriatrics, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- Department of Geriatrics, National Regional Medical Center, Binhai Campus of the First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Meng-Wen Wang
- Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Yu-Sen Qiu
- Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Ru-Ying Yuan
- Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Ning Wang
- Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, China
| | - Xiang Lin
- Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, China
| | - Wan-Jin Chen
- Department of Neurology and Institute of Neurology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- Fujian Key Laboratory of Molecular Neurology, Fujian Medical University, Fuzhou, China
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4
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Rad52's DNA annealing activity drives template switching associated with restarted DNA replication. Nat Commun 2022; 13:7293. [PMID: 36435847 PMCID: PMC9701231 DOI: 10.1038/s41467-022-35060-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 11/17/2022] [Indexed: 11/28/2022] Open
Abstract
It is thought that many of the simple and complex genomic rearrangements associated with congenital diseases and cancers stem from mistakes made during the restart of collapsed replication forks by recombination enzymes. It is hypothesised that this recombination-mediated restart process transitions from a relatively accurate initiation phase to a less accurate elongation phase characterised by extensive template switching between homologous, homeologous and microhomologous DNA sequences. Using an experimental system in fission yeast, where fork collapse is triggered by a site-specific replication barrier, we show that ectopic recombination, associated with the initiation of recombination-dependent replication (RDR), is driven mainly by the Rad51 recombinase, whereas template switching, during the elongation phase of RDR, relies more on DNA annealing by Rad52. This finding provides both evidence and a mechanistic basis for the transition hypothesis.
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5
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Balachandran P, Walawalkar IA, Flores JI, Dayton JN, Audano PA, Beck CR. Transposable element-mediated rearrangements are prevalent in human genomes. Nat Commun 2022; 13:7115. [PMID: 36402840 PMCID: PMC9675761 DOI: 10.1038/s41467-022-34810-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 11/08/2022] [Indexed: 11/21/2022] Open
Abstract
Transposable elements constitute about half of human genomes, and their role in generating human variation through retrotransposition is broadly studied and appreciated. Structural variants mediated by transposons, which we call transposable element-mediated rearrangements (TEMRs), are less well studied, and the mechanisms leading to their formation as well as their broader impact on human diversity are poorly understood. Here, we identify 493 unique TEMRs across the genomes of three individuals. While homology directed repair is the dominant driver of TEMRs, our sequence-resolved TEMR resource allows us to identify complex inversion breakpoints, triplications or other high copy number polymorphisms, and additional complexities. TEMRs are enriched in genic loci and can create potentially important risk alleles such as a deletion in TRIM65, a known cancer biomarker and therapeutic target. These findings expand our understanding of this important class of structural variation, the mechanisms responsible for their formation, and establish them as an important driver of human diversity.
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Affiliation(s)
| | | | - Jacob I Flores
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA
| | - Jacob N Dayton
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA
| | - Peter A Audano
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA
| | - Christine R Beck
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA.
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, USA.
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA.
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6
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Calame DG, Herman I, Marshall AE, Maroofian R, Donis KC, Fatih JM, Mitani T, Du H, Grochowski CM, Sousa S, Bakhtiari S, Ito YA, Rocca C, Hunter JV, Sutton VR, Emrick LT, Boycott KM, Lossos A, Fellig Y, Prus E, Kalish Y, Meiner V, Suerink M, Ruivenkamp C, Muirhead K, Saadi NW, Zaki MS, Skidmore DL, Osmond M, Silva TO, Houlden H, Murphy D, Ghayoorarimiani E, Jamshidi Y, Jaddoa AG, Tajsharghi H, Jin SC, Coban-Akdemir Z, Travaglini L, Nicita F, Jhangiani SN, Gibbs RA, Posey JE, Kruer MC, Kernohan KD, Morales Saute JA, Vanderver A, Pehlivan D, Marafi D, Lupski JR. Biallelic Variants in the Ectonucleotidase ENTPD1 Cause a Complex Neurodevelopmental Disorder with Intellectual Disability, Distinct White Matter Abnormalities, and Spastic Paraplegia. Ann Neurol 2022; 92:304-321. [PMID: 35471564 PMCID: PMC10054521 DOI: 10.1002/ana.26381] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 04/18/2022] [Accepted: 04/21/2022] [Indexed: 01/17/2023]
Abstract
OBJECTIVE Human genomics established that pathogenic variation in diverse genes can underlie a single disorder. For example, hereditary spastic paraplegia is associated with >80 genes, with frequently only few affected individuals described for each gene. Herein, we characterize a large cohort of individuals with biallelic variation in ENTPD1, a gene previously linked to spastic paraplegia 64 (Mendelian Inheritance in Man # 615683). METHODS Individuals with biallelic ENTPD1 variants were recruited worldwide. Deep phenotyping and molecular characterization were performed. RESULTS A total of 27 individuals from 17 unrelated families were studied; additional phenotypic information was collected from published cases. Twelve novel pathogenic ENTPD1 variants are described (NM 001776.6): c.398_399delinsAA; p.(Gly133Glu), c.540del; p.(Thr181Leufs*18), c.640del; p.(Gly216Glufs*75), c.185 T > G; p.(Leu62*), c.1531 T > C; p.(*511Glnext*100), c.967C > T; p.(Gln323*), c.414-2_414-1del, and c.146 A > G; p.(Tyr49Cys) including 4 recurrent variants c.1109 T > A; p.(Leu370*), c.574-6_574-3del, c.770_771del; p.(Gly257Glufs*18), and c.1041del; p.(Ile348Phefs*19). Shared disease traits include childhood onset, progressive spastic paraplegia, intellectual disability (ID), dysarthria, and white matter abnormalities. In vitro assays demonstrate that ENTPD1 expression and function are impaired and that c.574-6_574-3del causes exon skipping. Global metabolomics demonstrate ENTPD1 deficiency leads to impaired nucleotide, lipid, and energy metabolism. INTERPRETATION The ENTPD1 locus trait consists of childhood disease onset, ID, progressive spastic paraparesis, dysarthria, dysmorphisms, and white matter abnormalities, with some individuals showing neurocognitive regression. Investigation of an allelic series of ENTPD1 (1) expands previously described features of ENTPD1-related neurological disease, (2) highlights the importance of genotype-driven deep phenotyping, (3) documents the need for global collaborative efforts to characterize rare autosomal recessive disease traits, and (4) provides insights into disease trait neurobiology. ANN NEUROL 2022;92:304-321.
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Affiliation(s)
- Daniel G. Calame
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Isabella Herman
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Aren E. Marshall
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Reza Maroofian
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Karina Carvalho Donis
- Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Jawid M. Fatih
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Tadahiro Mitani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Haowei Du
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | | | | | - Somayeh Bakhtiari
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ, 85016, USA
- Departments of Child Health, Neurology, and Cellular & Molecular Medicine, and Program in Genetics, University of Arizona College of Medicine–Phoenix, Phoenix, AZ, USA
| | - Yoko A. Ito
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Clarissa Rocca
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Jill V. Hunter
- Texas Children’s Hospital, Houston, Texas, 77030, USA
- Division of Neuroradiology, Edward B. Singleton Department of Radiology, Texas Children’s Hospital, Houston, Texas
| | - V. Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Lisa T. Emrick
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Kym M. Boycott
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Alexander Lossos
- Department of Neurology, Hadassah Medical Organization and Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel
| | - Yakov Fellig
- Department of Pathology, Hadassah Medical Organization and Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel
| | - Eugenia Prus
- Hematology and Bone Marrow Transplantation Division, Hadassah Medical Center and the Hebrew University, POB 12000, 91120, Jerusalem, Israel
| | - Yosef Kalish
- Hematology and Bone Marrow Transplantation Division, Hadassah Medical Center and the Hebrew University, POB 12000, 91120, Jerusalem, Israel
| | - Vardiella Meiner
- Department of Genetics, Hadassah Medical Center and the Hebrew University, POB 12000, 91120, Jerusalem, Israel
| | - Manon Suerink
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Claudia Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Kayla Muirhead
- Division of Neurology, Children’s Hospital of Philadelphia, Abramson Research Center, 3615 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - Nebal W. Saadi
- College of Medicine / University of Baghdad, Children Welfare Teaching Hospital, Medical City Complex, Baghdad 10001, Iraq
| | - Maha S. Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, Centre of Excellence of Human Genetics, National Research Centre, Cairo, Egypt
| | - David L. Skidmore
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Matthew Osmond
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
| | - Thiago Oliveira Silva
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
- Postgraduate Program in Medicine: Medical Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Henry Houlden
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - David Murphy
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, University College London, United Kingdom
| | - Ehsan Ghayoorarimiani
- Genetics Section, Molecular and Clinical Sciences Institute, St. George’s University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Yalda Jamshidi
- Genetics Section, Molecular and Clinical Sciences Institute, St. George’s University of London, Cranmer Terrace, London SW17 0RE, UK
| | | | - Homa Tajsharghi
- School of Health Sciences, Division Biomedicine, University of Skovde, Skovde, Sweden
| | - Sheng Chih Jin
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Human Genetics Center, Department of Epidemiology, Human Genetics, and Environmental Sciences, School of Public Health, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Lorena Travaglini
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Molecular Medicine, Department of Neuroscience, IRCCS Bambino Gesù Children’s Hospital, 00146 Rome, Italy
| | - Francesco Nicita
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
- Laboratory of Molecular Medicine, Department of Neuroscience, IRCCS Bambino Gesù Children’s Hospital, 00146 Rome, Italy
| | - Shalini N. Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Richard A. Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Jennifer E. Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
| | - Michael C. Kruer
- Pediatric Movement Disorders Program, Division of Pediatric Neurology, Barrow Neurological Institute, Phoenix Children’s Hospital, Phoenix, AZ, 85016, USA
- Departments of Child Health, Neurology, and Cellular & Molecular Medicine, and Program in Genetics, University of Arizona College of Medicine–Phoenix, Phoenix, AZ, USA
| | - Kristin D. Kernohan
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, K1H 8L1, Canada
- Newborn Screening Ontario, Ottawa, Canada, K1H 8L1, Canada
| | - Jonas A. Morales Saute
- Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Internal Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Neurology Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Adeline Vanderver
- Division of Neurology, Children’s Hospital of Philadelphia, Abramson Research Center, 3615 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - Davut Pehlivan
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
| | - Dana Marafi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Pediatrics, Faculty of Medicine, Kuwait University, P.O. Box 24923, 13110 Safat, Kuwait
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, 77030, USA
- Texas Children’s Hospital, Houston, Texas, 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
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7
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Penon-Portmann M, Eldomery MK, Potocki L, Marafi D, Posey JE, Coban-Akdemir Z, Harel T, Grochowski CM, Loucks H, Devine WP, Van Ziffle J, Doherty D, Lupski JR, Shieh JT. De novo heterozygous variants in SLC30A7 are a candidate cause for Joubert syndrome. Am J Med Genet A 2022; 188:2360-2366. [PMID: 35751429 PMCID: PMC9756141 DOI: 10.1002/ajmg.a.62872] [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: 04/07/2022] [Accepted: 04/15/2022] [Indexed: 11/08/2022]
Abstract
Joubert syndrome (JS), a well-established ciliopathy, is characterized by the distinctive molar tooth sign on brain MRI, ataxia, and neurodevelopmental features. Other manifestations can include polydactyly, accessory frenula, renal, or liver disease. Here, we report individuals meeting criteria for JS with de novo heterozygous variants in SLC30A7 (Chr1p21.2). The first individual is a female with history of unilateral postaxial polydactyly, classic molar tooth sign on MRI, macrocephaly, ataxia, ocular motor apraxia, neurodevelopmental delay, and precocious puberty. Exome sequencing detected a de novo heterozygous missense variant in SLC30A7: NM_133496.5: c.407 T > C, (p.Val136Ala). The second individual had bilateral postaxial polydactyly, molar tooth sign, macrocephaly, developmental delay, and an extra oral frenulum. A de novo deletion-insertion variant in SLC30A7, c.490_491delinsAG (p.His164Ser) was found. Both de novo variants affect highly conserved residues. Variants were not identified in known Joubert genes for either case. SLC30A7 has not yet been associated with a human phenotype. The SLC30 family of zinc transporters, like SLC30A7, permit cellular efflux of zinc, and although it is expressed in the brain its functions remain unknown. Published data from proteomic studies support SLC30A7 interaction with TCTN3, another protein associated with JS. The potential involvement of such genes in primary cilia suggest a role in Sonic Hedgehog signaling. SLC30A7 is a candidate JS-associated gene. Future work could be directed toward further characterization of SLC30A7 variants and understanding its function.
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Affiliation(s)
- Monica Penon-Portmann
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Mohammad K Eldomery
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Lorraine Potocki
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA
| | - Dana Marafi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Jennifer E Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Human Genetics Center, Department of Epidemiology, Human Genetics, and Environmental Sciences, School of Public Health, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Tamar Harel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | | | - Hailey Loucks
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - Walter Patrick Devine
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Jessica Van Ziffle
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Dan Doherty
- Department of Pediatrics, University of Washington, Seattle, WA, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.,Texas Children's Hospital, Houston, Texas, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Joseph T Shieh
- Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
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8
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Hereditary Spastic Paraplegia: An Update. Int J Mol Sci 2022; 23:ijms23031697. [PMID: 35163618 PMCID: PMC8835766 DOI: 10.3390/ijms23031697] [Citation(s) in RCA: 51] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 12/21/2021] [Accepted: 01/28/2022] [Indexed: 12/12/2022] Open
Abstract
Hereditary spastic paraplegia (HSP) is a rare neurodegenerative disorder with the predominant clinical manifestation of spasticity in the lower extremities. HSP is categorised based on inheritance, the phenotypic characters, and the mode of molecular pathophysiology, with frequent degeneration in the axon of cervical and thoracic spinal cord’s lateral region, comprising the corticospinal routes. The prevalence ranges from 0.1 to 9.6 subjects per 100,000 reported around the globe. Though modern medical interventions help recognize and manage the disorder, the symptomatic measures remain below satisfaction. The present review assimilates the available data on HSP and lists down the chromosomes involved in its pathophysiology and the mutations observed in the respective genes on the chromosomes. It also sheds light on the treatment available along with the oral/intrathecal medications, physical therapies, and surgical interventions. Finally, we have discussed the related diagnostic techniques as well as the linked pharmacogenomics studies under future perspectives.
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Anticipation Can Be More Common in Hereditary Spastic Paraplegia with SPAST Mutations Than It Appears. Can J Neurol Sci 2021; 49:651-661. [PMID: 34353391 DOI: 10.1017/cjn.2021.188] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND OBJECTIVE Hereditary spastic paraplegia (HSP) is a heterogeneous neurodegenerative disorder with lower-limb spasticity and weakness. Different patterns of inheritance have been identified in HSP. Most autosomal-dominant HSPs (AD-HSPs) are associated with mutations of the SPAST gene (SPG4), leading to a pure form of HSP with variable age-at-onset (AAO). Anticipation, an earlier onset of disease, as well as aggravation of symptoms in successive generations, may be correlated to SPG4. Herein, we suggested that anticipation might be a relatively common finding in SPG4 families. METHODS Whole-exome sequencing was done on DNA of 14 unrelated Iranian AD-HSP probands. Data were analyzed, and candidate variants were PCR-amplified and sequenced by the Sanger method, subsequently checked in family members to co-segregation analysis. Multiplex ligation-dependent probe amplification (MLPA) was done for seven probands. Clinical features of the probands were recorded, and the probable anticipation was checked in these families. Other previous reported SPG4 families were investigated to anticipation. RESULTS Our findings showed that SPG4 was the common subtype of HSP; three families carried variants in the KIF5A, ATL1, and MFN2 genes, while five families harbored mutations in the SPAST gene. Clinical features of only SPG4 families indicated decreasing AAO in affected individuals of the successive generations, and this difference was significant (p-value <0.05). CONCLUSION It seems SPAST will be the first candidate gene in families that manifests a pure form of AD-HSP and anticipation. Therefore, it may be a powerful situation of genotype-phenotype correlation. However, the underlying mechanism of anticipation in these families is not clear yet.
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Shi M, Chen X, Zeng L, Li Z, Liang D, Wu L. The rare Alus element-mediated chimerism of multiple de novo complex rearrangement sequences in GAN result in giant axonal neuropathy. Clin Chim Acta 2019; 502:91-98. [PMID: 31877298 DOI: 10.1016/j.cca.2019.12.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 02/02/2023]
Abstract
Giant axonal neuropathy (GAN) is a rare and grievous autosomal recessive neurodegenerative disease due to loss-of-function mutation in GAN. However, the chimerism of complex rearrangement sequences of GAN has not been reported so far, and the mechanism for its complex rearrangements remains to be determined. We identified a family with clinical symptoms of GAN and aimed to reveal a genetic cause underlying this disease. By whole-exome sequencing in the patient we identified a novel homozygous frameshift mutation with 1 bp deletion (c.27delC) in GAN. However, when analyzed the patient's genomic DNA (gDNA) by quantitative real-time PCR and breakpoint DNA sequencing, we found the chimerism of multiple complex rearrangement sequences encompassing exon 1 of GAN in the patient's genome. The microhomology and localization of the breakpoint indicated that they may be caused by Alu repeat elements. We also found that the mRNA expression level of GAN in patient's lymphocyte was decreased, confirming the pathogenicity of these mutations. Our study is the first reported on many complex rearrangement sequences mosaic in GAN mediated by Alu element. The patient here is not a simple homozygous frameshift mutation, but a compound heterozygous paternal c.27delC mutation and the chimerism of multiple de novo complex rearrangement sequences in GAN. Our results may also provide new insights into the formation and pathogenicity of complex rearrangement in GAN, and may be helpful to genetic counseling and genetic testing. It also enriches the Alu-mediated disease-associated database which are important for correct clinical interpretation.
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Affiliation(s)
- Meizhen Shi
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, PR China
| | - Xin Chen
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, PR China
| | - Lanlan Zeng
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, PR China
| | - Zhuo Li
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, PR China
| | - Desheng Liang
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, PR China.
| | - Lingqian Wu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, PR China.
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11
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Distinct patterns of complex rearrangements and a mutational signature of microhomeology are frequently observed in PLP1 copy number gain structural variants. Genome Med 2019; 11:80. [PMID: 31818324 PMCID: PMC6902434 DOI: 10.1186/s13073-019-0676-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/10/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND We investigated the features of the genomic rearrangements in a cohort of 50 male individuals with proteolipid protein 1 (PLP1) copy number gain events who were ascertained with Pelizaeus-Merzbacher disease (PMD; MIM: 312080). We then compared our new data to previous structural variant mutagenesis studies involving the Xq22 region of the human genome. The aggregate data from 159 sequenced join-points (discontinuous sequences in the reference genome that are joined during the rearrangement process) were studied. Analysis of these data from 150 individuals enabled the spectrum and relative distribution of the underlying genomic mutational signatures to be delineated. METHODS Genomic rearrangements in PMD individuals with PLP1 copy number gain events were investigated by high-density customized array or clinical chromosomal microarray analysis and breakpoint junction sequence analysis. RESULTS High-density customized array showed that the majority of cases (33/50; ~ 66%) present with single duplications, although complex genomic rearrangements (CGRs) are also frequent (17/50; ~ 34%). Breakpoint mapping to nucleotide resolution revealed further previously unknown structural and sequence complexities, even in single duplications. Meta-analysis of all studied rearrangements that occur at the PLP1 locus showed that single duplications were found in ~ 54% of individuals and that, among all CGR cases, triplication flanked by duplications is the most frequent CGR array CGH pattern observed. Importantly, in ~ 32% of join-points, there is evidence for a mutational signature of microhomeology (highly similar yet imperfect sequence matches). CONCLUSIONS These data reveal a high frequency of CGRs at the PLP1 locus and support the assertion that replication-based mechanisms are prominent contributors to the formation of CGRs at Xq22. We propose that microhomeology can facilitate template switching, by stabilizing strand annealing of the primer using W-C base complementarity, and is a mutational signature for replicative repair.
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12
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Breakpoint junction features of seven DMD deletion mutations. Hum Genome Var 2019; 6:39. [PMID: 31645977 PMCID: PMC6804640 DOI: 10.1038/s41439-019-0070-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 07/22/2019] [Accepted: 07/23/2019] [Indexed: 11/25/2022] Open
Abstract
Duchenne muscular dystrophy is an inherited muscle wasting disease with severe symptoms and onset in early childhood. Duchenne muscular dystrophy is caused by loss-of-function mutations, most commonly deletions, within the DMD gene. Characterizing the junction points of large genomic deletions facilitates a more detailed model of the origins of these mutations and allows for a greater understanding of phenotypic variations associated with particular genotypes, potentially providing insights into the deletion mechanism. Here, we report sequencing of breakpoint junctions for seven patients with intragenic, whole-exon DMD deletions. Of the seven junction sequences identified, we found one instance of a “clean” break, three instances of microhomology (2–5 bp) at the junction site, and three complex rearrangements involving local sequences. Bioinformatics analysis of the upstream and downstream breakpoint regions revealed a possible role of short inverted repeats in the initiation of some of these deletion events. Researchers in Australia have identified new examples of the genomic factors and mechanisms that lead to deletions linked with Duchenne muscular dystrophy (DMD). DMD is an inherited neuromuscular disease which causes progressive deterioration of muscles and, in some cases, intellectual impairment. Using samples from seven DMD patients, Niall Keegan of Murdoch University in Perth and colleagues sequenced the DNA left behind around the deletions in the DMD gene which cause the disease. They found one clean break, three sections with short repeated sequences, and three with more complex rearrangements. The diversity of these findings led them to suggest that the deletions resulted from a diversity of genomic factors and repair mechanisms. Future work could incorporate these findings into a model to predict where deletions will occur, expanding our understanding of DMD and its causes.
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13
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Genetic and Clinical Profile of Chinese Patients with Autosomal Dominant Spastic Paraplegia. Mol Diagn Ther 2019; 23:781-789. [DOI: 10.1007/s40291-019-00426-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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14
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Hereditary spastic paraplegia: from diagnosis to emerging therapeutic approaches. Lancet Neurol 2019; 18:1136-1146. [PMID: 31377012 DOI: 10.1016/s1474-4422(19)30235-2] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/20/2019] [Accepted: 05/29/2019] [Indexed: 12/16/2022]
Abstract
Hereditary spastic paraplegia (HSP) describes a heterogeneous group of genetic neurodegenerative diseases characterised by progressive spasticity of the lower limbs. The pathogenic mechanism, associated clinical features, and imaging abnormalities vary substantially according to the affected gene and differentiating HSP from other genetic diseases associated with spasticity can be challenging. Next generation sequencing-based gene panels are now widely available but have limitations and a molecular diagnosis is not made in most suspected cases. Symptomatic management continues to evolve but with a greater understanding of the pathophysiological basis of individual HSP subtypes there are emerging opportunities to provide targeted molecular therapies and personalised medicine.
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15
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Bodea GO, McKelvey EGZ, Faulkner GJ. Retrotransposon-induced mosaicism in the neural genome. Open Biol 2019; 8:rsob.180074. [PMID: 30021882 PMCID: PMC6070720 DOI: 10.1098/rsob.180074] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 06/21/2018] [Indexed: 12/18/2022] Open
Abstract
Over the past decade, major discoveries in retrotransposon biology have depicted the neural genome as a dynamic structure during life. In particular, the retrotransposon LINE-1 (L1) has been shown to be transcribed and mobilized in the brain. Retrotransposition in the developing brain, as well as during adult neurogenesis, provides a milieu in which neural diversity can arise. Dysregulation of retrotransposon activity may also contribute to neurological disease. Here, we review recent reports of retrotransposon activity in the brain, and discuss the temporal nature of retrotransposition and its regulation in neural cells in response to stimuli. We also put forward hypotheses regarding the significance of retrotransposons for brain development and neurological function, and consider the potential implications of this phenomenon for neuropsychiatric and neurodegenerative conditions.
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Affiliation(s)
- Gabriela O Bodea
- Mater Research Institute-University of Queensland, TRI Building, Brisbane, Queensland 4102, Australia .,Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Eleanor G Z McKelvey
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute-University of Queensland, TRI Building, Brisbane, Queensland 4102, Australia .,Queensland Brain Institute, University of Queensland, Brisbane, Queensland 4072, Australia
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16
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Lupski JR. 2018 Victor A. McKusick Leadership Award: Molecular Mechanisms for Genomic and Chromosomal Rearrangements. Am J Hum Genet 2019; 104:391-406. [PMID: 30849326 PMCID: PMC6407437 DOI: 10.1016/j.ajhg.2018.12.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, and Texas Children's Hospital, Houston, TX 77030, USA.
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17
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Nazaryan-Petersen L, Eisfeldt J, Pettersson M, Lundin J, Nilsson D, Wincent J, Lieden A, Lovmar L, Ottosson J, Gacic J, Mäkitie O, Nordgren A, Vezzi F, Wirta V, Käller M, Hjortshøj TD, Jespersgaard C, Houssari R, Pignata L, Bak M, Tommerup N, Lundberg ES, Tümer Z, Lindstrand A. Replicative and non-replicative mechanisms in the formation of clustered CNVs are indicated by whole genome characterization. PLoS Genet 2018; 14:e1007780. [PMID: 30419018 PMCID: PMC6258378 DOI: 10.1371/journal.pgen.1007780] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 11/26/2018] [Accepted: 10/23/2018] [Indexed: 01/25/2023] Open
Abstract
Clustered copy number variants (CNVs) as detected by chromosomal microarray analysis (CMA) are often reported as germline chromothripsis. However, such cases might need further investigations by massive parallel whole genome sequencing (WGS) in order to accurately define the underlying complex rearrangement, predict the occurrence mechanisms and identify additional complexities. Here, we utilized WGS to delineate the rearrangement structure of 21 clustered CNV carriers first investigated by CMA and identified a total of 83 breakpoint junctions (BPJs). The rearrangements were further sub-classified depending on the patterns observed: I) Cases with only deletions (n = 8) often had additional structural rearrangements, such as insertions and inversions typical to chromothripsis; II) cases with only duplications (n = 7) or III) combinations of deletions and duplications (n = 6) demonstrated mostly interspersed duplications and BPJs enriched with microhomology. In two cases the rearrangement mutational signatures indicated both a breakage-fusion-bridge cycle process and haltered formation of a ring chromosome. Finally, we observed two cases with Alu- and LINE-mediated rearrangements as well as two unrelated individuals with seemingly identical clustered CNVs on 2p25.3, possibly a rare European founder rearrangement. In conclusion, through detailed characterization of the derivative chromosomes we show that multiple mechanisms are likely involved in the formation of clustered CNVs and add further evidence for chromoanagenesis mechanisms in both “simple” and highly complex chromosomal rearrangements. Finally, WGS characterization adds positional information, important for a correct clinical interpretation and deciphering mechanisms involved in the formation of these rearrangements. Clustered copy number variants (CNVs) as detected by chromosomal microarray are often reported as germline chromoanagenesis. However, such cases might need further investigation by whole genome sequencing (WGS) to accurately resolve the complexity of the structural rearrangement and predict underlying mutational mechanisms. Here, we used WGS to characterize 83 breakpoint-junctions (BPJs) from 21 clustered CNVs, and outlined the rearrangement connectivity pictures. Cases with only deletions often had additional structural rearrangements, such as insertions and inversions, which could be a result of multiple double-strand DNA breaks followed by non-homologous repair, typical to chromothripsis. In contrast, cases with only duplications or combinations of deletions and duplications, demonstrated mostly interspersed duplications and BPJs enriched with microhomology, consistent with serial template switching during DNA replication (chromoanasynthesis). Only two rearrangements were repeat mediated. In aggregate, our results suggest that multiple CNVs clustered on a single chromosome may arise through either chromothripsis or chromoanasynthesis.
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Affiliation(s)
- Lusine Nazaryan-Petersen
- Wilhelm Johannsen Center for Functional Genome Research, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Eisfeldt
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Science for Life Laboratory, Karolinska Institutet Science Park, Solna, Sweden
| | - Maria Pettersson
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
| | - Johanna Lundin
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Daniel Nilsson
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Science for Life Laboratory, Karolinska Institutet Science Park, Solna, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Josephine Wincent
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Agne Lieden
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Lovisa Lovmar
- Department of Clinical Genetics, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jesper Ottosson
- Department of Clinical Genetics, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Jelena Gacic
- Department of Clinical Genetics, Linköping University Hospital, Linköping, Sweden
| | - Outi Mäkitie
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
- Children’s Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Ann Nordgren
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Francesco Vezzi
- SciLifeLab, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Valtteri Wirta
- SciLifeLab, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
- SciLifeLab, Department of Microbiology, Tumor and Cell biology, Karolinska Institutet, Stockholm, Sweden
| | - Max Käller
- SciLifeLab, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
- SciLifeLab, Department of Microbiology, Tumor and Cell biology, Karolinska Institutet, Stockholm, Sweden
| | - Tina Duelund Hjortshøj
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Cathrine Jespersgaard
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Rayan Houssari
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Laura Pignata
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Mads Bak
- Wilhelm Johannsen Center for Functional Genome Research, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Niels Tommerup
- Wilhelm Johannsen Center for Functional Genome Research, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Elisabeth Syk Lundberg
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
- * E-mail: (AL); (ZT)
| | - Anna Lindstrand
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
- * E-mail: (AL); (ZT)
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Song X, Beck CR, Du R, Campbell IM, Coban-Akdemir Z, Gu S, Breman AM, Stankiewicz P, Ira G, Shaw CA, Lupski JR. Predicting human genes susceptible to genomic instability associated with Alu/ Alu-mediated rearrangements. Genome Res 2018; 28:1228-1242. [PMID: 29907612 PMCID: PMC6071635 DOI: 10.1101/gr.229401.117] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 06/06/2018] [Indexed: 12/14/2022]
Abstract
Alu elements, the short interspersed element numbering more than 1 million copies per human genome, can mediate the formation of copy number variants (CNVs) between substrate pairs. These Alu/Alu-mediated rearrangements (AAMRs) can result in pathogenic variants that cause diseases. To investigate the impact of AAMR on gene variation and human health, we first characterized Alus that are involved in mediating CNVs (CNV-Alus) and observed that these Alus tend to be evolutionarily younger. We then computationally generated, with the assistance of a supercomputer, a test data set consisting of 78 million Alu pairs and predicted ∼18% of them are potentially susceptible to AAMR. We further determined the relative risk of AAMR in 12,074 OMIM genes using the count of predicted CNV-Alu pairs and experimentally validated the predictions with 89 samples selected by correlating predicted hotspots with a database of CNVs identified by clinical chromosomal microarrays (CMAs) on the genomes of approximately 54,000 subjects. We fine-mapped 47 duplications, 40 deletions, and two complex rearrangements and examined a total of 52 breakpoint junctions of simple CNVs. Overall, 94% of the candidate breakpoints were at least partially Alu mediated. We successfully predicted all (100%) of Alu pairs that mediated deletions (n = 21) and achieved an 87% positive predictive value overall when including AAMR-generated deletions and duplications. We provided a tool, AluAluCNVpredictor, for assessing AAMR hotspots and their role in human disease. These results demonstrate the utility of our predictive model and provide insights into the genomic features and molecular mechanisms underlying AAMR.
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Affiliation(s)
- Xiaofei Song
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Christine R Beck
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Renqian Du
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Ian M Campbell
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Shen Gu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Amy M Breman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Baylor Genetics, Houston, Texas 77021, USA
| | - Pawel Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Baylor Genetics, Houston, Texas 77021, USA
| | - Grzegorz Ira
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Chad A Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Baylor Genetics, Houston, Texas 77021, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
- Texas Children's Hospital, Houston, Texas 77030, USA
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19
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Krestel H, Meier JC. RNA Editing and Retrotransposons in Neurology. Front Mol Neurosci 2018; 11:163. [PMID: 29875629 PMCID: PMC5974252 DOI: 10.3389/fnmol.2018.00163] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 04/30/2018] [Indexed: 12/28/2022] Open
Abstract
Compared to sites in protein-coding sequences many more targets undergoing adenosine to inosine (A-to-I) RNA editing were discovered in non-coding regions of human cerebral transcripts, particularly in genetic transposable elements called retrotransposons. We review here the interaction mechanisms of RNA editing and retrotransposons and their impact on normal function and human neurological diseases. Exemplarily, A-to-I editing of retrotransposons embedded in protein-coding mRNAs can contribute to protein abundance and function via circular RNA formation, alternative splicing, and exonization or silencing of retrotransposons. Interactions leading to disease are not very well understood. We describe human diseases with involvement of the central nervous system including inborn errors of metabolism, neurodevelopmental disorders, neuroinflammatory and neurodegenerative and paroxysmal diseases, in which retrotransposons (Alu and/or L1 elements) appear to be causally involved in genetic rearrangements. Sole binding of single-stranded retrotransposon transcripts by RNA editing enzymes rather than enzymatic deamination may have a homeostatic effect on retrotransposon turnover. We also review evidence in support of the emerging pathophysiological function of A-to-I editing of retrotransposons in inflammation and its implication for different neurological diseases including amyotrophic lateral sclerosis, frontotemporal dementia, Alzheimer's and Parkinson's disease, and epilepsy.
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Affiliation(s)
- Heinz Krestel
- Department of Neurology, Bern University Hospital and University of Bern, Bern, Switzerland.,Department for BioMedical Research, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Jochen C Meier
- Division Cell Physiology, Zoological Institute, Technical University Braunschweig, Braunschweig, Germany
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20
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White JJ, Mazzeu JF, Coban-Akdemir Z, Bayram Y, Bahrambeigi V, Hoischen A, van Bon BWM, Gezdirici A, Gulec EY, Ramond F, Touraine R, Thevenon J, Shinawi M, Beaver E, Heeley J, Hoover-Fong J, Durmaz CD, Karabulut HG, Marzioglu-Ozdemir E, Cayir A, Duz MB, Seven M, Price S, Ferreira BM, Vianna-Morgante AM, Ellard S, Parrish A, Stals K, Flores-Daboub J, Jhangiani SN, Gibbs RA, Brunner HG, Sutton VR, Lupski JR, Carvalho CMB. WNT Signaling Perturbations Underlie the Genetic Heterogeneity of Robinow Syndrome. Am J Hum Genet 2018; 102:27-43. [PMID: 29276006 DOI: 10.1016/j.ajhg.2017.10.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 10/06/2017] [Indexed: 12/12/2022] Open
Abstract
Locus heterogeneity characterizes a variety of skeletal dysplasias often due to interacting or overlapping signaling pathways. Robinow syndrome is a skeletal disorder historically refractory to molecular diagnosis, potentially stemming from substantial genetic heterogeneity. All current known pathogenic variants reside in genes within the noncanonical Wnt signaling pathway including ROR2, WNT5A, and more recently, DVL1 and DVL3. However, ∼70% of autosomal-dominant Robinow syndrome cases remain molecularly unsolved. To investigate this missing heritability, we recruited 21 families with at least one family member clinically diagnosed with Robinow or Robinow-like phenotypes and performed genetic and genomic studies. In total, four families with variants in FZD2 were identified as well as three individuals from two families with biallelic variants in NXN that co-segregate with the phenotype. Importantly, both FZD2 and NXN are relevant protein partners in the WNT5A interactome, supporting their role in skeletal development. In addition to confirming that clustered -1 frameshifting variants in DVL1 and DVL3 are the main contributors to dominant Robinow syndrome, we also found likely pathogenic variants in candidate genes GPC4 and RAC3, both linked to the Wnt signaling pathway. These data support an initial hypothesis that Robinow syndrome results from perturbation of the Wnt/PCP pathway, suggest specific relevant domains of the proteins involved, and reveal key contributors in this signaling cascade during human embryonic development. Contrary to the view that non-allelic genetic heterogeneity hampers gene discovery, this study demonstrates the utility of rare disease genomic studies to parse gene function in human developmental pathways.
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Affiliation(s)
- Janson J White
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA
| | - Juliana F Mazzeu
- University of Brasilia, Brasilia 70910, Brazil; Robinow Syndrome Foundation, Anoka, MN 55303, USA
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA
| | - Yavuz Bayram
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA
| | - Vahid Bahrambeigi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA; Graduate Program in Diagnostic Genetics, School of Health Professions, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Alexander Hoischen
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Department of Internal Medicine and Radboud Center for Infectious Diseases (RCI), Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Bregje W M van Bon
- Department of Human Genetics, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Alper Gezdirici
- Department of Medical Genetics, Kanuni Sultan Suleyman Training and Research Hospital, Istanbul 34303, Turkey
| | - Elif Yilmaz Gulec
- Department of Medical Genetics, Kanuni Sultan Suleyman Training and Research Hospital, Istanbul 34303, Turkey
| | - Francis Ramond
- Service de Génétique, CHU-Hôpital Nord, 42000 Saint-Etienne, France
| | - Renaud Touraine
- Service de Génétique, CHU-Hôpital Nord, 42000 Saint-Etienne, France
| | - Julien Thevenon
- Inserm UMR 1231 GAD team, Genetics of Developmental Anomalies, Université de Bourgogne-Franche Comté, 21000 Dijon, France; FHU-TRANSLAD, Université de Bourgogne, 21000 CHU Dijon, France; Centre de génétique, Hôpital Couple-Enfant, CHU de Grenoble-Alpes, 38700 La Tronche, France
| | - Marwan Shinawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Erin Beaver
- Mercy Clinic-Kids Genetics, Mercy Children's Hospital St. Louis, St. Louis, MO 63141, USA
| | - Jennifer Heeley
- Mercy Clinic-Kids Genetics, Mercy Children's Hospital St. Louis, St. Louis, MO 63141, USA
| | - Julie Hoover-Fong
- Greenberg Center for Skeletal Dysplasias, McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University, Baltimore, MD 21287, USA
| | - Ceren D Durmaz
- Department of Medical Genetics, Ankara University School of Medicine, 06100 Ankara, Turkey
| | - Halil Gurhan Karabulut
- Department of Medical Genetics, Ankara University School of Medicine, 06100 Ankara, Turkey
| | - Ebru Marzioglu-Ozdemir
- Department of Medical Genetics, Erzurum Regional and Training Hospital, 25070 Erzurum, Turkey
| | - Atilla Cayir
- Erzurum Training and Research Hospital, Department of Pediatric Endocrinology, 25070 Erzurum, Turkey
| | - Mehmet B Duz
- Department of Medical Genetics, Cerrahpasa Medical School, Istanbul University, 34452 Istanbul, Turkey
| | - Mehmet Seven
- Department of Medical Genetics, Cerrahpasa Medical School, Istanbul University, 34452 Istanbul, Turkey
| | - Susan Price
- Oxford Centre for Genomic Medicine, Nuffield Orthopaedic Centre, Oxford OX3 7LD, UK
| | | | - Angela M Vianna-Morgante
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, Sao Paulo - SP 05508-090, Brazil
| | - Sian Ellard
- Department of Molecular Genetics, Royal Devon and Exeter NHS Foundation Trust, Exeter EX2 5DW, UK; Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter EX1 2LU, UK
| | - Andrew Parrish
- Department of Molecular Genetics, Royal Devon and Exeter NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Karen Stals
- Department of Molecular Genetics, Royal Devon and Exeter NHS Foundation Trust, Exeter EX2 5DW, UK
| | - Josue Flores-Daboub
- Department of Pediatric Genetics, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - Shalini N Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Han G Brunner
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands; Department of Clinical Genetics, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, 6202 AZ Maastricht, the Netherlands
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston TX 77030, USA.
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21
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Gambin T, Akdemir ZC, Yuan B, Gu S, Chiang T, Carvalho CMB, Shaw C, Jhangiani S, Boone PM, Eldomery MK, Karaca E, Bayram Y, Stray-Pedersen A, Muzny D, Charng WL, Bahrambeigi V, Belmont JW, Boerwinkle E, Beaudet AL, Gibbs RA, Lupski JR. Homozygous and hemizygous CNV detection from exome sequencing data in a Mendelian disease cohort. Nucleic Acids Res 2017; 45:1633-1648. [PMID: 27980096 PMCID: PMC5389578 DOI: 10.1093/nar/gkw1237] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 11/29/2016] [Indexed: 11/14/2022] Open
Abstract
We developed an algorithm, HMZDelFinder, that uses whole exome sequencing (WES) data to identify rare and intragenic homozygous and hemizygous (HMZ) deletions that may represent complete loss-of-function of the indicated gene. HMZDelFinder was applied to 4866 samples in the Baylor–Hopkins Center for Mendelian Genomics (BHCMG) cohort and detected 773 HMZ deletion calls (567 homozygous or 206 hemizygous) with an estimated sensitivity of 86.5% (82% for single-exonic and 88% for multi-exonic calls) and precision of 78% (53% single-exonic and 96% for multi-exonic calls). Out of 773 HMZDelFinder-detected deletion calls, 82 were subjected to array comparative genomic hybridization (aCGH) and/or breakpoint PCR and 64 were confirmed. These include 18 single-exon deletions out of which 8 were exclusively detected by HMZDelFinder and not by any of seven other CNV detection tools examined. Further investigation of the 64 validated deletion calls revealed at least 15 pathogenic HMZ deletions. Of those, 7 accounted for 17–50% of pathogenic CNVs in different disease cohorts where 7.1–11% of the molecular diagnosis solved rate was attributed to CNVs. In summary, we present an algorithm to detect rare, intragenic, single-exon deletion CNVs using WES data; this tool can be useful for disease gene discovery efforts and clinical WES analyses.
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Affiliation(s)
- Tomasz Gambin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Institute of Computer Science, Warsaw University of Technology, Warsaw, 00-665 Warsaw, Poland
| | - Zeynep C Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Bo Yuan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shen Gu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Theodore Chiang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chad Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shalini Jhangiani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Philip M Boone
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mohammad K Eldomery
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ender Karaca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yavuz Bayram
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Asbjørg Stray-Pedersen
- Norwegian National Unit for Newborn Screening, Division for Pediatric and Adolescent Medicine, Oslo University Hospital, N-0424 Oslo, Norway
| | - Donna Muzny
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Wu-Lin Charng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Vahid Bahrambeigi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Graduate Program in Diagnostic Genetics, School of Health Professions, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - John W Belmont
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Eric Boerwinkle
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA.,Human Genetics Center, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Arthur L Beaudet
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.,Texas Children's Hospital, Houston, TX 77030, USA
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22
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Matthews AM, Tarailo-Graovac M, Price EM, Blydt-Hansen I, Ghani A, Drögemöller BI, Robinson WP, Ross CJ, Wasserman WW, Siden H, van Karnebeek CD. A de novo mosaic mutation in SPAST with two novel alternative alleles and chromosomal copy number variant in a boy with spastic paraplegia and autism spectrum disorder. Eur J Med Genet 2017; 60:548-552. [PMID: 28778789 DOI: 10.1016/j.ejmg.2017.07.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 07/30/2017] [Accepted: 07/30/2017] [Indexed: 11/30/2022]
Abstract
Here we report a 12 year old male with an extreme presentation of spastic paraplegia along with autism and dysmorphisms. Whole exome sequencing identified a predicted pathogenic pair of missense variants in SPAST at the same chromosomal location, each with a different alternative allele, while a chromosome microarray identified a 1.73 Mb paternally inherited copy gain of 1q21.1q21.2 resulting in a blended phenotype of both Spastic paraplegia 4 and 1q21.1 microduplication syndrome. We believe that the extreme phenotype observed is likely caused by the presence of cells which contain only mutant SPAST, but that the viability of the patient is possible due mosaicism of mutant alleles observed in different proportions across tissues.
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Affiliation(s)
- A M Matthews
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - M Tarailo-Graovac
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - E M Price
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - I Blydt-Hansen
- BC Children's Hospital Research Institute, Vancouver, BC, Canada; Department of Pediatrics, BC Children's Hospital, Vancouver, BC, Canada
| | - A Ghani
- Department of Pediatrics, BC Children's Hospital, Vancouver, BC, Canada
| | - B I Drögemöller
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada; Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - W P Robinson
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - C J Ross
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada; Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - W W Wasserman
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada
| | - H Siden
- BC Children's Hospital Research Institute, Vancouver, BC, Canada; Department of Pediatrics, BC Children's Hospital, Vancouver, BC, Canada; Canuck Place Children's Hospice, Vancouver, BC, Canada
| | - C D van Karnebeek
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada; BC Children's Hospital Research Institute, Vancouver, BC, Canada; Department of Pediatrics, BC Children's Hospital, Vancouver, BC, Canada; Departments of Pediatrics and Clinical Genetics, Academic Medical Centre, University of Amsterdam, The Netherlands.
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23
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Van Schil K, Naessens S, Van de Sompele S, Carron M, Aslanidis A, Van Cauwenbergh C, Kathrin Mayer A, Van Heetvelde M, Bauwens M, Verdin H, Coppieters F, Greenberg ME, Yang MG, Karlstetter M, Langmann T, De Preter K, Kohl S, Cherry TJ, Leroy BP, De Baere E. Mapping the genomic landscape of inherited retinal disease genes prioritizes genes prone to coding and noncoding copy-number variations. Genet Med 2017; 20:202-213. [PMID: 28749477 PMCID: PMC5787040 DOI: 10.1038/gim.2017.97] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/19/2017] [Indexed: 01/08/2023] Open
Abstract
PurposePart of the hidden genetic variation in heterogeneous genetic conditions such as inherited retinal diseases (IRDs) can be explained by copy-number variations (CNVs). Here, we explored the genomic landscape of IRD genes listed in RetNet to identify and prioritize those genes susceptible to CNV formation.MethodsRetNet genes underwent an assessment of genomic features and of CNV occurrence in the Database of Genomic Variants and literature. CNVs identified in an IRD cohort were characterized using targeted locus amplification (TLA) on extracted genomic DNA.ResultsExhaustive literature mining revealed 1,345 reported CNVs in 81 different IRD genes. Correlation analysis between rankings of genomic features and CNV occurrence demonstrated the strongest correlation between gene size and CNV occurrence of IRD genes. Moreover, we identified and delineated 30 new CNVs in IRD cases, 13 of which are novel and three of which affect noncoding, putative cis-regulatory regions. Finally, the breakpoints of six complex CNVs were determined using TLA in a hypothesis-neutral manner.ConclusionWe propose a ranking of CNV-prone IRD genes and demonstrate the efficacy of TLA for the characterization of CNVs on extracted DNA. Finally, this IRD-oriented CNV study can serve as a paradigm for other genetically heterogeneous Mendelian diseases with hidden genetic variation.
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Affiliation(s)
- Kristof Van Schil
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Sarah Naessens
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Stijn Van de Sompele
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Marjolein Carron
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Alexander Aslanidis
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | | | - Anja Kathrin Mayer
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Mattias Van Heetvelde
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Miriam Bauwens
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Hannah Verdin
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Frauke Coppieters
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Michael E Greenberg
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Marty G Yang
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Marcus Karlstetter
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Katleen De Preter
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany
| | - Timothy J Cherry
- Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA.,Center for Developmental Biology and Regenerative Medicine, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Bart P Leroy
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium.,Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium.,Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | - Elfride De Baere
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
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24
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Liu P, Yuan B, Carvalho CMB, Wuster A, Walter K, Zhang L, Gambin T, Chong Z, Campbell IM, Coban Akdemir Z, Gelowani V, Writzl K, Bacino CA, Lindsay SJ, Withers M, Gonzaga-Jauregui C, Wiszniewska J, Scull J, Stankiewicz P, Jhangiani SN, Muzny DM, Zhang F, Chen K, Gibbs RA, Rautenstrauss B, Cheung SW, Smith J, Breman A, Shaw CA, Patel A, Hurles ME, Lupski JR. An Organismal CNV Mutator Phenotype Restricted to Early Human Development. Cell 2017; 168:830-842.e7. [PMID: 28235197 DOI: 10.1016/j.cell.2017.01.037] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 10/13/2016] [Accepted: 01/27/2017] [Indexed: 01/07/2023]
Abstract
De novo copy number variants (dnCNVs) arising at multiple loci in a personal genome have usually been considered to reflect cancer somatic genomic instabilities. We describe a multiple dnCNV (MdnCNV) phenomenon in which individuals with genomic disorders carry five to ten constitutional dnCNVs. These CNVs originate from independent formation incidences, are predominantly tandem duplications or complex gains, exhibit breakpoint junction features reminiscent of replicative repair, and show increased de novo point mutations flanking the rearrangement junctions. The active CNV mutation shower appears to be restricted to a transient perizygotic period. We propose that a defect in the CNV formation process is responsible for the "CNV-mutator state," and this state is dampened after early embryogenesis. The constitutional MdnCNV phenomenon resembles chromosomal instability in various cancers. Investigations of this phenomenon may provide unique access to understanding genomic disorders, structural variant mutagenesis, human evolution, and cancer biology.
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Affiliation(s)
- Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA.
| | - Bo Yuan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Arthur Wuster
- Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK
| | | | - Ling Zhang
- Collaborative Innovation Center of Genetics and Development, Institute of Reproduction and Development, Obstetrics and Gynecology Hospital of Fudan University, Shanghai 200011, China
| | - Tomasz Gambin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zechen Chong
- Department of Bioinformatics and Computational Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Ian M Campbell
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zeynep Coban Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Violet Gelowani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Karin Writzl
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, 1000 Ljubljana, Slovenia
| | - Carlos A Bacino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | | | - Marjorie Withers
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Joanna Wiszniewska
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jennifer Scull
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA
| | - Paweł Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA
| | - Shalini N Jhangiani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Donna M Muzny
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Feng Zhang
- Collaborative Innovation Center of Genetics and Development, Institute of Reproduction and Development, Obstetrics and Gynecology Hospital of Fudan University, Shanghai 200011, China
| | - Ken Chen
- Department of Bioinformatics and Computational Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Richard A Gibbs
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Sau Wai Cheung
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA
| | - Janice Smith
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA
| | - Amy Breman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA
| | - Chad A Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA
| | - Ankita Patel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics, Houston, TX 77021, USA
| | | | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA.
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25
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Nilsson D, Pettersson M, Gustavsson P, Förster A, Hofmeister W, Wincent J, Zachariadis V, Anderlid BM, Nordgren A, Mäkitie O, Wirta V, Käller M, Vezzi F, Lupski JR, Nordenskjöld M, Lundberg ES, Carvalho CMB, Lindstrand A. Whole-Genome Sequencing of Cytogenetically Balanced Chromosome Translocations Identifies Potentially Pathological Gene Disruptions and Highlights the Importance of Microhomology in the Mechanism of Formation. Hum Mutat 2017; 38:180-192. [PMID: 27862604 PMCID: PMC5225243 DOI: 10.1002/humu.23146] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 11/01/2016] [Indexed: 11/07/2022]
Abstract
Most balanced translocations are thought to result mechanistically from nonhomologous end joining or, in rare cases of recurrent events, by nonallelic homologous recombination. Here, we use low-coverage mate pair whole-genome sequencing to fine map rearrangement breakpoint junctions in both phenotypically normal and affected translocation carriers. In total, 46 junctions from 22 carriers of balanced translocations were characterized. Genes were disrupted in 48% of the breakpoints; recessive genes in four normal carriers and known dominant intellectual disability genes in three affected carriers. Finally, seven candidate disease genes were disrupted in five carriers with neurocognitive disabilities (SVOPL, SUSD1, TOX, NCALD, SLC4A10) and one XX-male carrier with Tourette syndrome (LYPD6, GPC5). Breakpoint junction analyses revealed microhomology and small templated insertions in a substantive fraction of the analyzed translocations (17.4%; n = 4); an observation that was substantiated by reanalysis of 37 previously published translocation junctions. Microhomology associated with templated insertions is a characteristic seen in the breakpoint junctions of rearrangements mediated by error-prone replication-based repair mechanisms. Our data implicate that a mechanism involving template switching might contribute to the formation of at least 15% of the interchromosomal translocation events.
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Affiliation(s)
- Daniel Nilsson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
- Science for Life Laboratory, Karolinska Institutet Science Park, 171 21 Solna, Sweden
| | - Maria Pettersson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Peter Gustavsson
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Alisa Förster
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Wolfgang Hofmeister
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Josephine Wincent
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Vasilios Zachariadis
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Britt-Marie Anderlid
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Ann Nordgren
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Outi Mäkitie
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
- Children's Hospital, Helsinki University Central Hospital and University of Helsinki, 00290 Helsinki, Finland
- Folkhälsan Institute of Genetics, 00290 Helsinki, Finland
| | - Valtteri Wirta
- SciLifeLab, School of Biotechnology, KTH Royal Institute of Technology, 171 71 Stockholm, Sweden
| | - Max Käller
- SciLifeLab, School of Biotechnology, KTH Royal Institute of Technology, 171 71 Stockholm, Sweden
| | - Francesco Vezzi
- SciLifeLab, Department of Biochemistry and Biophysics, Stockholm University, 171 21 Stockholm, Sweden
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, 77030 Houston TX, USA
- Texas Children’s Hospital, 77030 Houston TX, USA
| | - Magnus Nordenskjöld
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Elisabeth Syk Lundberg
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Claudia M. B. Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, 77030 Houston TX, USA
| | - Anna Lindstrand
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden
- Center for Molecular Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 76 Stockholm, Sweden
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26
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Jahic A, Hinreiner S, Emberger W, Hehr U, Zuchner S, Beetz C. Doublet-Mediated DNA Rearrangement-A Novel and Potentially Underestimated Mechanism for the Formation of Recurrent Pathogenic Deletions. Hum Mutat 2016; 38:275-278. [PMID: 28008689 DOI: 10.1002/humu.23162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/02/2016] [Accepted: 12/14/2016] [Indexed: 11/09/2022]
Abstract
Deletions and duplications of genomic DNA contribute to evolution, phenotypic diversity, and human disease. The underlying mechanisms are incompletely understood. We identified deletions of exon 10 of the SPAST gene in two unrelated families with hereditary spastic paraplegia. We excluded a founder event, but observed that the breakpoints map to identical repeat regions. These regions likely represent an intragenic "doublet," that is, an enigmatic class of local duplications. The fusion sequences for both deletions are compatible with recombination-based as well as with replication-based mechanisms. Searching the literature, we identified a partial SLC24A4 deletion that involved two copies of another doublet, and was likely formed in an analogous way. Comparing the SPAST and the SLC24A4 doublets with doublets identified previously suggested that many additional doublets have a high potential for triggering rearrangements. Considering that doublets are still being formed in the human genome, and that they likely create high local instability, we suggest that a two-step mechanism consisting of doublet generation and subsequent doublet-mediated deletion/duplication may underlie certain copy-number changes for which other mechanisms are currently assumed. Further studies are necessary to delineate the significance of the thus-far understudied doublets for the formation of copy-number variation.
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Affiliation(s)
- Amir Jahic
- Department of Clinical Chemistry and Laboratory Medicine, Jena University Hospital, Jena, Germany
| | - Sophie Hinreiner
- Department of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Werner Emberger
- Department of Human Genetics, Graz Medical University, Graz, Austria
| | - Ute Hehr
- Department of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Stephan Zuchner
- John T. Macdonald Department of Human Genetics and John P. Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, Florida
| | - Christian Beetz
- Department of Clinical Chemistry and Laboratory Medicine, Jena University Hospital, Jena, Germany
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27
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Kim S, Cho CS, Han K, Lee J. Structural Variation of Alu Element and Human Disease. Genomics Inform 2016; 14:70-77. [PMID: 27729835 PMCID: PMC5056899 DOI: 10.5808/gi.2016.14.3.70] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 01/04/2023] Open
Abstract
Transposable elements are one of major sources to cause genomic instability through various mechanisms including de novo insertion, insertion-mediated genomic deletion, and recombination-associated genomic deletion. Among them is Alu element which is the most abundant element, composing ~10% of the human genome. The element emerged in the primate genome 65 million years ago and has since propagated successfully in the human and non-human primate genomes. Alu element is a non-autonomous retrotransposon and therefore retrotransposed using L1-enzyme machinery. The 'master gene' model has been generally accepted to explain Alu element amplification in primate genomes. According to the model, different subfamilies of Alu elements are created by mutations on the master gene and most Alu elements are amplified from the hyperactive master genes. Alu element is frequently involved in genomic rearrangements in the human genome due to its abundance and sequence identity between them. The genomic rearrangements caused by Alu elements could lead to genetic disorders such as hereditary disease, blood disorder, and neurological disorder. In fact, Alu elements are associated with approximately 0.1% of human genetic disorders. The first part of this review discusses mechanisms of Alu amplification and diversity among different Alu subfamilies. The second part discusses the particular role of Alu elements in generating genomic rearrangements as well as human genetic disorders.
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Affiliation(s)
- Songmi Kim
- Department of Nanobiomedical Science, Dankook University, Cheonan 31116, Korea.; BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 31116, Korea
| | - Chun-Sung Cho
- Department of Neurosurgery, Dankook University College of Medicine, Cheonan 31116, Korea
| | - Kyudong Han
- Department of Nanobiomedical Science, Dankook University, Cheonan 31116, Korea.; BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 31116, Korea
| | - Jungnam Lee
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Florida, Gainesville, FL 32610, USA
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28
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Lindstrand A, Frangakis S, Carvalho C, Richardson E, McFadden K, Willer J, Pehlivan D, Liu P, Pediaditakis I, Sabo A, Lewis R, Banin E, Lupski J, Davis E, Katsanis N. Copy-Number Variation Contributes to the Mutational Load of Bardet-Biedl Syndrome. Am J Hum Genet 2016; 99:318-36. [PMID: 27486776 DOI: 10.1016/j.ajhg.2015.04.023] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 06/13/2016] [Indexed: 12/15/2022] Open
Abstract
Bardet-Biedl syndrome (BBS) is a defining ciliopathy, notable for extensive allelic and genetic heterogeneity, almost all of which has been identified through sequencing. Recent data have suggested that copy-number variants (CNVs) also contribute to BBS. We used a custom oligonucleotide array comparative genomic hybridization (aCGH) covering 20 genes that encode intraflagellar transport (IFT) components and 74 ciliopathy loci to screen 92 unrelated individuals with BBS, irrespective of their known mutational burden. We identified 17 individuals with exon-disruptive CNVs (18.5%), including 13 different deletions in eight BBS genes (BBS1, BBS2, ARL6/BBS3, BBS4, BBS5, BBS7, BBS9, and NPHP1) and a deletion and a duplication in other ciliopathy-associated genes (ALMS1 and NPHP4, respectively). By contrast, we found a single heterozygous exon-disruptive event in a BBS-associated gene (BBS9) in 229 control subjects. Superimposing these data with resequencing revealed CNVs to (1) be sufficient to cause disease, (2) Mendelize heterozygous deleterious alleles, and (3) contribute oligogenic alleles by combining point mutations and exonic CNVs in multiple genes. Finally, we report a deletion and a splice site mutation in IFT74, inherited under a recessive paradigm, defining a candidate BBS locus. Our data suggest that CNVs contribute pathogenic alleles to a substantial fraction of BBS-affected individuals and highlight how either deletions or point mutations in discrete splice isoforms can induce hypomorphic mutations in genes otherwise intolerant to deleterious variation. Our data also suggest that CNV analyses and resequencing studies unbiased for previous mutational burden is necessary to delineate the complexity of disease architecture.
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29
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Yuan B, Neira J, Gu S, Harel T, Liu P, Briceño I, Elsea SH, Gómez A, Potocki L, Lupski JR. Nonrecurrent PMP22-RAI1 contiguous gene deletions arise from replication-based mechanisms and result in Smith-Magenis syndrome with evident peripheral neuropathy. Hum Genet 2016; 135:1161-74. [PMID: 27386852 DOI: 10.1007/s00439-016-1703-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/21/2016] [Indexed: 11/29/2022]
Abstract
Hereditary neuropathy with liability to pressure palsies (HNPP) and Smith-Magenis syndrome (SMS) are genomic disorders associated with deletion copy number variants involving chromosome 17p12 and 17p11.2, respectively. Nonallelic homologous recombination (NAHR)-mediated recurrent deletions are responsible for the majority of HNPP and SMS cases; the rearrangement products encompass the key dosage-sensitive genes PMP22 and RAI1, respectively, and result in haploinsufficiency for these genes. Less frequently, nonrecurrent genomic rearrangements occur at this locus. Contiguous gene duplications encompassing both PMP22 and RAI1, i.e., PMP22-RAI1 duplications, have been investigated, and replication-based mechanisms rather than NAHR have been proposed for these rearrangements. In the current study, we report molecular and clinical characterizations of six subjects with the reciprocal phenomenon of deletions spanning both genes, i.e., PMP22-RAI1 deletions. Molecular studies utilizing high-resolution array comparative genomic hybridization and breakpoint junction sequencing identified mutational signatures that were suggestive of replication-based mechanisms. Systematic clinical studies revealed features consistent with SMS, including features of intellectual disability, speech and gross motor delays, behavioral problems and ocular abnormalities. Five out of six subjects presented clinical signs and/or objective electrophysiologic studies of peripheral neuropathy. Clinical profiling may improve the clinical management of this unique group of subjects, as the peripheral neuropathy can be more severe or of earlier onset as compared to SMS patients having the common recurrent deletion. Moreover, the current study, in combination with the previous report of PMP22-RAI1 duplications, contributes to the understanding of rare complex phenotypes involving multiple dosage-sensitive genes from a genetic mechanistic standpoint.
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Affiliation(s)
- Bo Yuan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Juanita Neira
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Shen Gu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Tamar Harel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Ignacio Briceño
- Instituto de Genética Humana, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá, Colombia
- Instituto de Referencia Andino, Bogotá, Colombia
- Facultad de Medicina, Universidad de La Sabana, Chía, Colombia
| | - Sarah H Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Alberto Gómez
- Instituto de Genética Humana, Facultad de Medicina, Pontificia Universidad Javeriana, Bogotá, Colombia
- Instituto de Referencia Andino, Bogotá, Colombia
| | - Lorraine Potocki
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Texas Children's Hospital, Houston, TX, 77030, USA
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, 77030, USA.
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA.
- Texas Children's Hospital, Houston, TX, 77030, USA.
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30
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Carvalho CMB, Lupski JR. Mechanisms underlying structural variant formation in genomic disorders. Nat Rev Genet 2016; 17:224-38. [PMID: 26924765 DOI: 10.1038/nrg.2015.25] [Citation(s) in RCA: 414] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
With the recent burst of technological developments in genomics, and the clinical implementation of genome-wide assays, our understanding of the molecular basis of genomic disorders, specifically the contribution of structural variation to disease burden, is evolving quickly. Ongoing studies have revealed a ubiquitous role for genome architecture in the formation of structural variants at a given locus, both in DNA recombination-based processes and in replication-based processes. These reports showcase the influence of repeat sequences on genomic stability and structural variant complexity and also highlight the tremendous plasticity and dynamic nature of our genome in evolution, health and disease susceptibility.
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Affiliation(s)
- Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.,Centro de Pesquisas René Rachou - FIOCRUZ, Belo Horizonte, MG 30190-002, Brazil
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA.,Texas Children's Hospital, Houston, Texas 77030, USA
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31
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Mutational spectrum of the SPAST and ATL1 genes in Korean patients with hereditary spastic paraplegia. J Neurol Sci 2015. [DOI: 10.1016/j.jns.2015.07.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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32
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Virts EL, Jankowska A, Mackay C, Glaas MF, Wiek C, Kelich SL, Lottmann N, Kennedy FM, Marchal C, Lehnert E, Scharf RE, Dufour C, Lanciotti M, Farruggia P, Santoro A, Savasan S, Scheckenbach K, Schipper J, Wagenmann M, Lewis T, Leffak M, Farlow JL, Foroud TM, Honisch E, Niederacher D, Chakraborty SC, Vance GH, Pruss D, Timms KM, Lanchbury JS, Alpi AF, Hanenberg H. AluY-mediated germline deletion, duplication and somatic stem cell reversion in UBE2T defines a new subtype of Fanconi anemia. Hum Mol Genet 2015; 24:5093-108. [PMID: 26085575 PMCID: PMC4550815 DOI: 10.1093/hmg/ddv227] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/12/2015] [Indexed: 01/09/2023] Open
Abstract
Fanconi anemia (FA) is a rare inherited disorder clinically characterized by congenital malformations, progressive bone marrow failure and cancer susceptibility. At the cellular level, FA is associated with hypersensitivity to DNA-crosslinking genotoxins. Eight of 17 known FA genes assemble the FA E3 ligase complex, which catalyzes monoubiquitination of FANCD2 and is essential for replicative DNA crosslink repair. Here, we identify the first FA patient with biallelic germline mutations in the ubiquitin E2 conjugase UBE2T. Both mutations were aluY-mediated: a paternal deletion and maternal duplication of exons 2-6. These loss-of-function mutations in UBE2T induced a cellular phenotype similar to biallelic defects in early FA genes with the absence of FANCD2 monoubiquitination. The maternal duplication produced a mutant mRNA that could encode a functional protein but was degraded by nonsense-mediated mRNA decay. In the patient's hematopoietic stem cells, the maternal allele with the duplication of exons 2-6 spontaneously reverted to a wild-type allele by monoallelic recombination at the duplicated aluY repeat, thereby preventing bone marrow failure. Analysis of germline DNA of 814 normal individuals and 850 breast cancer patients for deletion or duplication of UBE2T exons 2-6 identified the deletion in only two controls, suggesting aluY-mediated recombinations within the UBE2T locus are rare and not associated with an increased breast cancer risk. Finally, a loss-of-function germline mutation in UBE2T was detected in a high-risk breast cancer patient with wild-type BRCA1/2. Cumulatively, we identified UBE2T as a bona fide FA gene (FANCT) that also may be a rare cancer susceptibility gene.
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Affiliation(s)
| | | | - Craig Mackay
- Department of MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee, UK
| | - Marcel F Glaas
- Department of Otorhinolaryngology and Head/Neck Surgery (ENT) and
| | - Constanze Wiek
- Department of Otorhinolaryngology and Head/Neck Surgery (ENT) and
| | | | - Nadine Lottmann
- Department of Otorhinolaryngology and Head/Neck Surgery (ENT) and
| | | | | | - Erik Lehnert
- Department of Experimental and Clinical Hemostasis, Hemotherapy and Transfusion Medicine, Heinrich Heine University, Düsseldorf, Germany
| | - Rüdiger E Scharf
- Department of Experimental and Clinical Hemostasis, Hemotherapy and Transfusion Medicine, Heinrich Heine University, Düsseldorf, Germany
| | - Carlo Dufour
- Hematology Unit, G. Gaslini Children's Hospital, Genoa, Italy
| | | | - Piero Farruggia
- Pediatric Hematology and Oncology Unit, A.R.N.A.S. Ospedale Civico, Palermo, Italy
| | | | - Süreyya Savasan
- Department of Pediatrics, Children's Hospital of Michigan, Wayne State University School of Medicine, Detroit, MI, USA
| | | | - Jörg Schipper
- Department of Otorhinolaryngology and Head/Neck Surgery (ENT) and
| | - Martin Wagenmann
- Department of Otorhinolaryngology and Head/Neck Surgery (ENT) and
| | - Todd Lewis
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Michael Leffak
- Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, OH 45435, USA
| | - Janice L Farlow
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Tatiana M Foroud
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Ellen Honisch
- Department of Gynecology, Heinrich Heine University, Düsseldorf, Germany and
| | - Dieter Niederacher
- Department of Gynecology, Heinrich Heine University, Düsseldorf, Germany and
| | - Sujata C Chakraborty
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Gail H Vance
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | | | | | - Arno F Alpi
- Department of MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, University of Dundee, Dundee, UK,
| | - Helmut Hanenberg
- Department of Pediatrics and Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Department of Otorhinolaryngology and Head/Neck Surgery (ENT) and
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33
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Gu S, Yuan B, Campbell IM, Beck CR, Carvalho CMB, Nagamani SCS, Erez A, Patel A, Bacino CA, Shaw CA, Stankiewicz P, Cheung SW, Bi W, Lupski JR. Alu-mediated diverse and complex pathogenic copy-number variants within human chromosome 17 at p13.3. Hum Mol Genet 2015; 24:4061-77. [PMID: 25908615 DOI: 10.1093/hmg/ddv146] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 04/20/2015] [Indexed: 01/05/2023] Open
Abstract
Alu repetitive elements are known to be major contributors to genome instability by generating Alu-mediated copy-number variants (CNVs). Most of the reported Alu-mediated CNVs are simple deletions and duplications, and the mechanism underlying Alu-Alu-mediated rearrangement has been attributed to non-allelic homologous recombination (NAHR). Chromosome 17 at the p13.3 genomic region lacks extensive low-copy repeat architecture; however, it is highly enriched for Alu repetitive elements, with a fraction of 30% of total sequence annotated in the human reference genome, compared with the 10% genome-wide and 18% on chromosome 17. We conducted mechanistic studies of the 17p13.3 CNVs by performing high-density oligonucleotide array comparative genomic hybridization, specifically interrogating the 17p13.3 region with ∼150 bp per probe density; CNV breakpoint junctions were mapped to nucleotide resolution by polymerase chain reaction and Sanger sequencing. Studied rearrangements include 5 interstitial deletions, 14 tandem duplications, 7 terminal deletions and 13 complex genomic rearrangements (CGRs). Within the 17p13.3 region, Alu-Alu-mediated rearrangements were identified in 80% of the interstitial deletions, 46% of the tandem duplications and 50% of the CGRs, indicating that this mechanism was a major contributor for formation of breakpoint junctions. Our studies suggest that Alu repetitive elements facilitate formation of non-recurrent CNVs, CGRs and other structural aberrations of chromosome 17 at p13.3. The common observation of Alu-mediated rearrangement in CGRs and breakpoint junction sequences analysis further demonstrates that this type of mechanism is unlikely attributed to NAHR, but rather may be due to a recombination-coupled DNA replicative repair process.
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Affiliation(s)
- Shen Gu
- Department of Molecular & Human Genetics
| | - Bo Yuan
- Department of Molecular & Human Genetics
| | | | | | | | - Sandesh C S Nagamani
- Department of Molecular & Human Genetics, Texas Children's Hospital, Houston, TX 77030, USA and
| | - Ayelet Erez
- Department of Molecular & Human Genetics, Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | | | - Carlos A Bacino
- Department of Molecular & Human Genetics, Texas Children's Hospital, Houston, TX 77030, USA and
| | | | | | | | - Weimin Bi
- Department of Molecular & Human Genetics
| | - James R Lupski
- Department of Molecular & Human Genetics, Department of Pediatrics and Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA, Texas Children's Hospital, Houston, TX 77030, USA and
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The Alu-rich genomic architecture of SPAST predisposes to diverse and functionally distinct disease-associated CNV alleles. Am J Hum Genet 2014; 95:143-61. [PMID: 25065914 DOI: 10.1016/j.ajhg.2014.06.014] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 06/30/2014] [Indexed: 01/27/2023] Open
Abstract
Intragenic copy-number variants (CNVs) contribute to the allelic spectrum of both Mendelian and complex disorders. Although pathogenic deletions and duplications in SPAST (mutations in which cause autosomal-dominant spastic paraplegia 4 [SPG4]) have been described, their origins and molecular consequences remain obscure. We mapped breakpoint junctions of 54 SPAST CNVs at nucleotide resolution. Diverse combinations of exons are deleted or duplicated, highlighting the importance of particular exons for spastin function. Of the 54 CNVs, 38 (70%) appear to be mediated by an Alu-based mechanism, suggesting that the Alu-rich genomic architecture of SPAST renders this locus susceptible to various genome rearrangements. Analysis of breakpoint Alus further informs a model of Alu-mediated CNV formation characterized by small CNV size and potential involvement of mechanisms other than homologous recombination. Twelve deletions (22%) overlap part of SPAST and a portion of a nearby, directly oriented gene, predicting novel chimeric genes in these subjects' genomes. cDNA from a subject with a SPAST final exon deletion contained multiple SPAST:SLC30A6 fusion transcripts, indicating that SPAST CNVs can have transcriptional effects beyond the gene itself. SLC30A6 has been implicated in Alzheimer disease, so these fusion gene data could explain a report of spastic paraplegia and dementia cosegregating in a family with deletion of the final exon of SPAST. Our findings provide evidence that the Alu genomic architecture of SPAST predisposes to diverse CNV alleles with distinct transcriptional--and possibly phenotypic--consequences. Moreover, we provide further mechanistic insights into Alu-mediated copy-number change that are extendable to other loci.
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35
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Schanze D, Neubauer D, Cormier-Daire V, Delrue MA, Dieux-Coeslier A, Hasegawa T, Holmberg EE, Koenig R, Krueger G, Schanze I, Seemanova E, Shaw AC, Vogt J, Volleth M, Reis A, Meinecke P, Hennekam RCM, Zenker M. Deletions in the 3' part of the NFIX gene including a recurrent Alu-mediated deletion of exon 6 and 7 account for previously unexplained cases of Marshall-Smith syndrome. Hum Mutat 2014; 35:1092-100. [PMID: 24924640 DOI: 10.1002/humu.22603] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 06/03/2014] [Indexed: 01/30/2023]
Abstract
Marshall-Smith syndrome (MSS) is a very rare malformation syndrome characterized by typical craniofacial anomalies, abnormal osseous maturation, developmental delay, failure to thrive, and respiratory difficulties. Mutations in the nuclear factor 1/X gene (NFIX) were recently identified as the cause of MSS. In our study cohort of 17 patients with a clinical diagnosis of MSS, conventional sequencing of NFIX revealed frameshift and splice-site mutations in 10 individuals. Using multiplex ligation-dependent probe amplification analysis, we identified a recurrent deletion of NFIX exon 6 and 7 in five individuals. We demonstrate this recurrent deletion is the product of a recombination between AluY elements located in intron 5 and 7. Two other patients had smaller deletions affecting exon 6. These findings show that MSS is a genetically homogeneous Mendelian disorder. RT-PCR experiments with newly identified NFIX mutations including the recurrent exon 6 and 7 deletion confirmed previous findings indicating that MSS-associated mutant mRNAs are not cleared by nonsense-mediated mRNA decay. Predicted MSS-associated mutant NFIX proteins consistently have a preserved DNA binding and dimerization domain, whereas they grossly vary in their C-terminal portion. This is in line with the hypothesis that MSS-associated mutations encode dysfunctional proteins that act in a dominant negative manner.
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Affiliation(s)
- Denny Schanze
- Institute of Human Genetics, University Hospital Magdeburg, Magdeburg, Germany
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36
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Suzuki J, Azuma N, Dateki S, Soneda S, Muroya K, Yamamoto Y, Saito R, Sano S, Nagai T, Wada H, Endo A, Urakami T, Ogata T, Fukami M. Mutation spectrum and phenotypic variation in nine patients with SOX2 abnormalities. J Hum Genet 2014; 59:353-6. [PMID: 24804704 DOI: 10.1038/jhg.2014.34] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 04/09/2014] [Accepted: 04/10/2014] [Indexed: 01/14/2023]
Abstract
Multiple mutations in SOX2 have been identified in patients with ocular anomalies and/or pituitary dysfunction. Here, we identified SOX2 abnormalities in nine patients. The molecular defects included one missense, one nonsense and four frameshift mutations, and three submicroscopic deletions involving SOX2. Three of the six mutations and all deletions were hitherto unreported. The breakpoints determined in one deletion were located within Alu repeats and accompanied by an overlap of 11 bp. Three of the six mutations encoded SOX2 proteins that lacked in vitro transactivation activity for the HESX1 promoter, whereas the remaining three generated proteins with ∼15-∼20% of transactivation activity. All cases manifested ocular anomalies of various severities, together with several complications including arachnoid cyst and hamartoma. There was no apparent correlation between the residual activity and clinical severity. The results indicate that molecular defects in SOX2 are highly variable and include Alu repeat-mediated genomic rearrangements. Our data provide further evidence for wide phenotypic variation of SOX2 abnormalities and the lack of genotype-phenotype correlation in patients carrying SOX2 lesions.
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Affiliation(s)
- Junichi Suzuki
- 1] National Research Institute for Child Health and Development, Department of Molecular Endocrinology, Tokyo, Japan [2] Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Noriyuki Azuma
- National Center for Child Health and Development, Department of Ophthalmology and Laboratory of Cell Biology, Tokyo, Japan
| | - Sumito Dateki
- 1] National Research Institute for Child Health and Development, Department of Molecular Endocrinology, Tokyo, Japan [2] Department of Pediatrics, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Shun Soneda
- National Research Institute for Child Health and Development, Department of Molecular Endocrinology, Tokyo, Japan
| | - Koji Muroya
- Kanagawa Children's Medical Center, Department of Endocrinology and Metabolism, Yokohama, Japan
| | - Yukiyo Yamamoto
- Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan
| | - Reiko Saito
- Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Fukuoka, Japan
| | - Shinichiro Sano
- National Research Institute for Child Health and Development, Department of Molecular Endocrinology, Tokyo, Japan
| | - Toshiro Nagai
- Department of Pediatrics, Koshigaya Hospital, Dokkyo Medical University, Koshigaya, Japan
| | - Hiroshi Wada
- Department of Pediatrics, Yodogawa Christian Hospital, Osaka, Japan
| | - Akira Endo
- Department of Pediatrics, Iwata City Hospital, Iwata, Japan
| | - Tatsuhiko Urakami
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Tsutomu Ogata
- 1] National Research Institute for Child Health and Development, Department of Molecular Endocrinology, Tokyo, Japan [2] Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Maki Fukami
- National Research Institute for Child Health and Development, Department of Molecular Endocrinology, Tokyo, Japan
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37
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Fukami M, Tsuchiya T, Vollbach H, Brown KA, Abe S, Ohtsu S, Wabitsch M, Burger H, Simpson ER, Umezawa A, Shihara D, Nakabayashi K, Bulun SE, Shozu M, Ogata T. Genomic basis of aromatase excess syndrome: recombination- and replication-mediated rearrangements leading to CYP19A1 overexpression. J Clin Endocrinol Metab 2013; 98:E2013-21. [PMID: 24064691 PMCID: PMC5399493 DOI: 10.1210/jc.2013-2520] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Genomic rearrangements at 15q21 have been shown to cause overexpression of CYP19A1 and resultant aromatase excess syndrome (AEXS). However, mutation spectrum, clinical consequences, and underlying mechanisms of these rearrangements remain to be elucidated. OBJECTIVE The aim of the study was to clarify such unsolved matters. DESIGN, SETTING, AND METHODS We characterized six new rearrangements and investigated clinical outcome and local genomic environments of these rearrangements and of three previously reported duplications/deletions. RESULTS Novel rearrangements included simple duplication involving exons 1-10 of CYP19A1 and simple and complex rearrangements that presumably generated chimeric genes consisting of the coding region of CYP19A1 and promoter-associated exons of neighboring genes. Clinical severities were primarily determined by the copy number of CYP19A1 and the property of the fused promoters. Sequences at the fusion junctions suggested nonallelic homologous recombination, nonhomologous end-joining, and replication-based errors as the underlying mechanisms. The breakpoint-flanking regions were not enriched with GC content, palindromes, noncanonical DNA structures, or known rearrangement-associated motifs. The rearrangements resided in early-replicating segments. CONCLUSIONS These results indicate that AEXS is caused by duplications involving CYP19A1 and simple and complex rearrangements that presumably lead to the usage of cryptic promoters of several neighboring genes. Our data support the notion that phenotypes depend on the dosage of CYP19A1 and the characteristics of the fused promoters. Furthermore, we show that the rearrangements in AEXS are generated by both recombination- and replication-mediated mechanisms, independent of the known rearrangement-inducing DNA features or late-replication timing. Thus, AEXS represents a unique model for human genomic disorders.
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MESH Headings
- 46, XX Disorders of Sex Development/genetics
- 46, XX Disorders of Sex Development/metabolism
- 46, XX Disorders of Sex Development/physiopathology
- Adolescent
- Adult
- Aromatase/biosynthesis
- Aromatase/deficiency
- Aromatase/genetics
- Aromatase/metabolism
- Child
- DNA Replication
- Gene Deletion
- Gene Dosage
- Gene Duplication
- Gene Fusion
- Gene Rearrangement
- Gynecomastia/genetics
- Gynecomastia/metabolism
- Gynecomastia/physiopathology
- Humans
- Infertility, Male/genetics
- Infertility, Male/metabolism
- Infertility, Male/physiopathology
- Male
- Metabolism, Inborn Errors/genetics
- Metabolism, Inborn Errors/metabolism
- Metabolism, Inborn Errors/physiopathology
- Promoter Regions, Genetic
- Recombination, Genetic
- Severity of Illness Index
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Affiliation(s)
- Maki Fukami
- MD, Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Ohkura, Setagaya, Tokyo 157-8535, Japan.
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38
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Euteneuer J, Carvalho CMB, Kulkarni S, Vineyard M, Grady RM, Lupski JR, Shinawi M. Molecular and phenotypic characterization of atypical Williams-Beuren syndrome. Clin Genet 2013; 86:487-91. [PMID: 24246242 DOI: 10.1111/cge.12305] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 10/08/2013] [Accepted: 10/16/2013] [Indexed: 11/29/2022]
Abstract
Williams-Beuren syndrome (WBS) is a multisystemic genomic disorder typically caused by a recurrent ˜1.5-1.8 Mb deletion on 7q11.23. Atypical deletions can provide important insight into the genotype-phenotype correlations. Here, we report the phenotypic and molecular characterization of a girl with a de novo 81.8 kb deletion in the WBS critical region, which involves the ELN and LIMK1 genes only. The patient presented at 2 months of age with extensive vascular abnormalities, mild facial dysmorphism and delays in her fine motor skills. We discuss potential molecular mechanisms and the role of ELN and LIMK1 in the different phenotypic features. We compare the findings in our patient with previously reported overlapping deletions. The phenotypic variability among these patients suggests that other factors are important in the phenotype and possibly include: position effects related to copy number variation size, variations in the non-deleted alleles, genetic modifiers elsewhere in the genome, or reduced penetrance for specific phenotypes.
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Affiliation(s)
- J Euteneuer
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
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39
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Sen P, Yang Y, Navarro C, Silva I, Szafranski P, Kolodziejska KE, Dharmadhikari AV, Mostafa H, Kozakewich H, Kearney D, Cahill JB, Whitt M, Bilic M, Margraf L, Charles A, Goldblatt J, Gibson K, Lantz PE, Garvin AJ, Petty J, Kiblawi Z, Zuppan C, McConkie-Rosell A, McDonald MT, Peterson-Carmichael SL, Gaede JT, Shivanna B, Schady D, Friedlich PS, Hays SR, Palafoll IV, Siebers-Renelt U, Bohring A, Finn LS, Siebert JR, Galambos C, Nguyen L, Riley M, Chassaing N, Vigouroux A, Rocha G, Fernandes S, Brumbaugh J, Roberts K, Ho-Ming L, Lo IFM, Lam S, Gerychova R, Jezova M, Valaskova I, Fellmann F, Afshar K, Giannoni E, Muhlethaler V, Liang J, Beckmann JS, Lioy J, Deshmukh H, Srinivasan L, Swarr DT, Sloman M, Shaw-Smith C, van Loon RL, Hagman C, Sznajer Y, Barrea C, Galant C, Detaille T, Wambach JA, Cole FS, Hamvas A, Prince LS, Diderich KEM, Brooks AS, Verdijk RM, Ravindranathan H, Sugo E, Mowat D, Baker ML, Langston C, Welty S, Stankiewicz P. Novel FOXF1 mutations in sporadic and familial cases of alveolar capillary dysplasia with misaligned pulmonary veins imply a role for its DNA binding domain. Hum Mutat 2013; 34:801-11. [PMID: 23505205 PMCID: PMC3663886 DOI: 10.1002/humu.22313] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 02/22/2013] [Indexed: 11/11/2022]
Abstract
Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare and lethal developmental disorder of the lung defined by a constellation of characteristic histopathological features. Nonpulmonary anomalies involving organs of gastrointestinal, cardiovascular, and genitourinary systems have been identified in approximately 80% of patients with ACD/MPV. We have collected DNA and pathological samples from more than 90 infants with ACD/MPV and their family members. Since the publication of our initial report of four point mutations and 10 deletions, we have identified an additional 38 novel nonsynonymous mutations of FOXF1 (nine nonsense, seven frameshift, one inframe deletion, 20 missense, and one no stop). This report represents an up to date list of all known FOXF1 mutations to the best of our knowledge. Majority of the cases are sporadic. We report four familial cases of which three show maternal inheritance, consistent with paternal imprinting of the gene. Twenty five mutations (60%) are located within the putative DNA-binding domain, indicating its plausible role in FOXF1 function. Five mutations map to the second exon. We identified two additional genic and eight genomic deletions upstream to FOXF1. These results corroborate and extend our previous observations and further establish involvement of FOXF1 in ACD/MPV and lung organogenesis.
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Affiliation(s)
- Partha Sen
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
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40
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Wiszniewska J, Bi W, Shaw C, Stankiewicz P, Kang SHL, Pursley AN, Lalani S, Hixson P, Gambin T, Tsai CH, Bock HG, Descartes M, Probst FJ, Scaglia F, Beaudet AL, Lupski JR, Eng C, Cheung SW, Bacino C, Patel A. Combined array CGH plus SNP genome analyses in a single assay for optimized clinical testing. Eur J Hum Genet 2013; 22:79-87. [PMID: 23695279 PMCID: PMC3865406 DOI: 10.1038/ejhg.2013.77] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 01/28/2013] [Accepted: 03/12/2013] [Indexed: 02/06/2023] Open
Abstract
In clinical diagnostics, both array comparative genomic hybridization (array CGH) and single nucleotide polymorphism (SNP) genotyping have proven to be powerful genomic technologies utilized for the evaluation of developmental delay, multiple congenital anomalies, and neuropsychiatric disorders. Differences in the ability to resolve genomic changes between these arrays may constitute an implementation challenge for clinicians: which platform (SNP vs array CGH) might best detect the underlying genetic cause for the disease in the patient? While only SNP arrays enable the detection of copy number neutral regions of absence of heterozygosity (AOH), they have limited ability to detect single-exon copy number variants (CNVs) due to the distribution of SNPs across the genome. To provide comprehensive clinical testing for both CNVs and copy-neutral AOH, we enhanced our custom-designed high-resolution oligonucleotide array that has exon-targeted coverage of 1860 genes with 60 000 SNP probes, referred to as Chromosomal Microarray Analysis – Comprehensive (CMA-COMP). Of the 3240 cases evaluated by this array, clinically significant CNVs were detected in 445 cases including 21 cases with exonic events. In addition, 162 cases (5.0%) showed at least one AOH region >10 Mb. We demonstrate that even though this array has a lower density of SNP probes than other commercially available SNP arrays, it reliably detected AOH events >10 Mb as well as exonic CNVs beyond the detection limitations of SNP genotyping. Thus, combining SNP probes and exon-targeted array CGH into one platform provides clinically useful genetic screening in an efficient manner.
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Affiliation(s)
- Joanna Wiszniewska
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Weimin Bi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Chad Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Pawel Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Sung-Hae L Kang
- Allina Cytogenetics Laboratory, Abbott Northwestern Hospital, Minneapolis, MN, USA
| | - Amber N Pursley
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Seema Lalani
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Patricia Hixson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Tomasz Gambin
- Institute of Computer Science, Warsaw University of Technology, Warsaw, Poland
| | - Chun-hui Tsai
- 1] Department of Molecular and Medical Genetics, Oregon Health and Sciences University-OHSU, Portland, OR, USA [2] Department of Pediatrics, The Children's Hospital, University of Colorado School of Medicine, Aurora, CO, USA
| | - Hans-Georg Bock
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS, USA
| | - Maria Descartes
- Department of Genetics, University of Alabama, Birmingham, AL, USA
| | - Frank J Probst
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Arthur L Beaudet
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - James R Lupski
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Christine Eng
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Sau Wai Cheung
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Carlos Bacino
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Ankita Patel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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Hellen EH, Brookfield JF. Alu elements in primates are preferentially lost from areas of high GC content. PeerJ 2013; 1:e78. [PMID: 23717800 PMCID: PMC3661076 DOI: 10.7717/peerj.78] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 05/02/2013] [Indexed: 11/20/2022] Open
Abstract
The currently-accepted dogma when analysing human Alu transposable elements is that ‘young’ Alu elements are found in low GC regions and ‘old’ Alus in high GC regions. The correlation between high GC regions and high gene frequency regions make this observation particularly difficult to explain. Although a number of studies have tackled the problem, no analysis has definitively explained the reason for this trend. These observations have been made by relying on the subfamily as a proxy for age of an element. In this study, we suggest that this is a misleading assumption and instead analyse the relationship between the taxonomic distribution of an individual element and its surrounding GC environment. An analysis of 103906 Alu elements across 6 human chromosomes was carried out, using the presence of orthologous Alu elements in other primate species as a proxy for age. We show that the previously-reported effect of GC content correlating with subfamily age is not reflected by the ages of the individual elements. Instead, elements are preferentially lost from areas of high GC content over time. The correlation between GC content and subfamily may be due to a change in insertion bias in the young subfamilies. The link between Alu subfamily age and GC region was made due to an over-simplification of the data and is incorrect. We suggest that use of subfamilies as a proxy for age is inappropriate and that the analysis of ortholog presence in other primate species provides a deeper insight into the data.
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Affiliation(s)
- Elizabeth Hb Hellen
- Centre for Genetics and Genomics, School of Biology, University of Nottingham , University Park, Nottingham , UK
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42
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Boone PM, Campbell IM, Baggett BC, Soens ZT, Rao MM, Hixson PM, Patel A, Bi W, Cheung SW, Lalani SR, Beaudet AL, Stankiewicz P, Shaw CA, Lupski JR. Deletions of recessive disease genes: CNV contribution to carrier states and disease-causing alleles. Genome Res 2013; 23:1383-94. [PMID: 23685542 PMCID: PMC3759716 DOI: 10.1101/gr.156075.113] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Over 1200 recessive disease genes have been described in humans. The prevalence, allelic architecture, and per-genome load of pathogenic alleles in these genes remain to be fully elucidated, as does the contribution of DNA copy-number variants (CNVs) to carrier status and recessive disease. We mined CNV data from 21,470 individuals obtained by array-comparative genomic hybridization in a clinical diagnostic setting to identify deletions encompassing or disrupting recessive disease genes. We identified 3212 heterozygous potential carrier deletions affecting 419 unique recessive disease genes. Deletion frequency of these genes ranged from one occurrence to 1.5%. When compared with recessive disease genes never deleted in our cohort, the 419 recessive disease genes affected by at least one carrier deletion were longer and located farther from known dominant disease genes, suggesting that the formation and/or prevalence of carrier CNVs may be affected by both local and adjacent genomic features and by selection. Some subjects had multiple carrier CNVs (307 subjects) and/or carrier deletions encompassing more than one recessive disease gene (206 deletions). Heterozygous deletions spanning multiple recessive disease genes may confer carrier status for multiple single-gene disorders, for complex syndromes resulting from the combination of two or more recessive conditions, or may potentially cause clinical phenotypes due to a multiply heterozygous state. In addition to carrier mutations, we identified homozygous and hemizygous deletions potentially causative for recessive disease. We provide further evidence that CNVs contribute to the allelic architecture of both carrier and recessive disease-causing mutations. Thus, a complete recessive carrier screening method or diagnostic test should detect CNV alleles.
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Affiliation(s)
- Philip M Boone
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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43
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Verdin H, D'haene B, Beysen D, Novikova Y, Menten B, Sante T, Lapunzina P, Nevado J, Carvalho CMB, Lupski JR, De Baere E. Microhomology-mediated mechanisms underlie non-recurrent disease-causing microdeletions of the FOXL2 gene or its regulatory domain. PLoS Genet 2013; 9:e1003358. [PMID: 23516377 PMCID: PMC3597517 DOI: 10.1371/journal.pgen.1003358] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 01/18/2013] [Indexed: 11/17/2022] Open
Abstract
Genomic disorders are often caused by recurrent copy number variations (CNVs), with nonallelic homologous recombination (NAHR) as the underlying mechanism. Recently, several microhomology-mediated repair mechanisms—such as microhomology-mediated end-joining (MMEJ), fork stalling and template switching (FoSTeS), microhomology-mediated break-induced replication (MMBIR), serial replication slippage (SRS), and break-induced SRS (BISRS)—were described in the etiology of non-recurrent CNVs in human disease. In addition, their formation may be stimulated by genomic architectural features. It is, however, largely unexplored to what extent these mechanisms contribute to rare, locus-specific pathogenic CNVs. Here, fine-mapping of 42 microdeletions of the FOXL2 locus, encompassing FOXL2 (32) or its regulatory domain (10), serves as a model for rare, locus-specific CNVs implicated in genetic disease. These deletions lead to blepharophimosis syndrome (BPES), a developmental condition affecting the eyelids and the ovary. For breakpoint mapping we used targeted array-based comparative genomic hybridization (aCGH), quantitative PCR (qPCR), long-range PCR, and Sanger sequencing of the junction products. Microhomology, ranging from 1 bp to 66 bp, was found in 91.7% of 24 characterized breakpoint junctions, being significantly enriched in comparison with a random control sample. Our results show that microhomology-mediated repair mechanisms underlie at least 50% of these microdeletions. Moreover, genomic architectural features, like sequence motifs, non-B DNA conformations, and repetitive elements, were found in all breakpoint regions. In conclusion, the majority of these microdeletions result from microhomology-mediated mechanisms like MMEJ, FoSTeS, MMBIR, SRS, or BISRS. Moreover, we hypothesize that the genomic architecture might drive their formation by increasing the susceptibility for DNA breakage or promote replication fork stalling. Finally, our locus-centered study, elucidating the etiology of a large set of rare microdeletions involved in a monogenic disorder, can serve as a model for other clustered, non-recurrent microdeletions in genetic disease. Genomic disorder is a general term describing conditions caused by genomic aberrations leading to a copy number change of one or more genes. Copy number changes with the same length and clustered breakpoints for a group of patients with the same disorder are named recurrent rearrangements. These originate mostly from a well-studied mechanism, namely nonallelic homologous recombination (NAHR). In contrast, non-recurrent rearrangements vary in size, have scattered breakpoints, and can originate from several different mechanisms that are not fully understood. Here we tried to gain further insight into the extent to which these mechanisms contribute to non-recurrent rearrangements and into the possible role of the surrounding genomic architecture. To this end, we investigated a unique group of patients with non-recurrent deletions of the FOXL2 region causing blepharophimosis syndrome. We observed that the majority of these deletions can result from several mechanisms mediated by microhomology. Furthermore, our data suggest that rare pathogenic microdeletions do not occur at random genome sequences, but are possibly guided by the surrounding genomic architecture. Finally, our study, elucidating the etiology of a unique cohort of locus-specific microdeletions implicated in genetic disease, can serve as a model for the formation of genomic aberrations in other genetic disorders.
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Affiliation(s)
- Hannah Verdin
- Center for Medical Genetics, Ghent University, Ghent, Belgium
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44
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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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Human subtelomeric copy number gains suggest a DNA replication mechanism for formation: beyond breakage-fusion-bridge for telomere stabilization. Hum Genet 2012; 131:1895-910. [PMID: 22890305 DOI: 10.1007/s00439-012-1216-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 08/01/2012] [Indexed: 12/19/2022]
Abstract
Constitutional deletions of distal 9q34 encompassing the EHMT1 (euchromatic histone methyltransferase 1) gene, or loss-of-function point mutations in EHMT1, are associated with the 9q34.3 microdeletion syndrome, also known as Kleefstra syndrome [MIM#610253]. We now report further evidence for genomic instability of the subtelomeric 9q34.3 region as evidenced by copy number gains of this genomic interval that include duplications, triplications, derivative chromosomes and complex rearrangements. Comparisons between the observed shared clinical features and molecular analyses in 20 subjects suggest that increased dosage of EHMT1 may be responsible for the neurodevelopmental impairment, speech delay, and autism spectrum disorders revealing the dosage sensitivity of yet another chromatin remodeling protein in human disease. Five patients had 9q34 genomic abnormalities resulting in complex deletion-duplication or duplication-triplication rearrangements; such complex triplications were also observed in six other subtelomeric intervals. Based on the specific structure of these complex genomic rearrangements (CGR) a DNA replication mechanism is proposed confirming recent findings in Caenorhabditis elegans telomere healing. The end-replication challenges of subtelomeric genomic intervals may make them particularly prone to rearrangements generated by errors in DNA replication.
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A common X-linked inborn error of carnitine biosynthesis may be a risk factor for nondysmorphic autism. Proc Natl Acad Sci U S A 2012; 109:7974-81. [PMID: 22566635 DOI: 10.1073/pnas.1120210109] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We recently reported a deletion of exon 2 of the trimethyllysine hydroxylase epsilon (TMLHE) gene in a proband with autism. TMLHE maps to the X chromosome and encodes the first enzyme in carnitine biosynthesis, 6-N-trimethyllysine dioxygenase. Deletion of exon 2 of TMLHE causes enzyme deficiency, resulting in increased substrate concentration (6-N-trimethyllysine) and decreased product levels (3-hydroxy-6-N-trimethyllysine and γ-butyrobetaine) in plasma and urine. TMLHE deficiency is common in control males (24 in 8,787 or 1 in 366) and was not significantly increased in frequency in probands from simplex autism families (9 in 2,904 or 1 in 323). However, it was 2.82-fold more frequent in probands from male-male multiplex autism families compared with controls (7 in 909 or 1 in 130; P = 0.023). Additionally, six of seven autistic male siblings of probands in male-male multiplex families had the deletion, suggesting that TMLHE deficiency is a risk factor for autism (metaanalysis Z-score = 2.90 and P = 0.0037), although with low penetrance (2-4%). These data suggest that dysregulation of carnitine metabolism may be important in nondysmorphic autism; that abnormalities of carnitine intake, loss, transport, or synthesis may be important in a larger fraction of nondysmorphic autism cases; and that the carnitine pathway may provide a novel target for therapy or prevention of autism.
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Liu P, Lacaria M, Zhang F, Withers M, Hastings P, Lupski J. Frequency of nonallelic homologous recombination is correlated with length of homology: evidence that ectopic synapsis precedes ectopic crossing-over. Am J Hum Genet 2011; 89:580-8. [PMID: 21981782 DOI: 10.1016/j.ajhg.2011.09.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 09/14/2011] [Accepted: 09/15/2011] [Indexed: 10/16/2022] Open
Abstract
Genomic disorders constitute a class of diseases that are associated with DNA rearrangements resulting from region-specific genome instability, that is, genome architecture incites genome instability. Nonallelic homologous recombination (NAHR) or crossing-over in meiosis between sequences that are not in allelic positions (i.e., paralogous sequences) can result in recurrent deletions or duplications causing genomic disorders. Previous studies of NAHR have focused on description of the phenomenon, but it remains unclear how NAHR occurs during meiosis and what factors determine its frequency. Here we assembled two patient cohorts with reciprocal genomic disorders; deletion associated Smith-Magenis syndrome and duplication associated Potocki-Lupski syndrome. By assessing the full spectrum of rearrangement types from the two cohorts, we find that complex rearrangements (those with more than one breakpoint) are more prevalent in copy-number gains (17.7%) than in copy-number losses (2.3%); an observation that supports a role for replicative mechanisms in complex rearrangement formation. Interestingly, for NAHR-mediated recurrent rearrangements, we show that crossover frequency is positively associated with the flanking low-copy repeat (LCR) length and inversely influenced by the inter-LCR distance. To explain this, we propose that the probability of ectopic chromosome synapsis increases with increased LCR length, and that ectopic synapsis is a necessary precursor to ectopic crossing-over.
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