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Ma D, Sun C, Manne R, Guo T, Bosc C, Barry J, Magliery T, Andrieux A, Li H, Gu C. A cytoskeleton-membrane interaction conserved in fast-spiking neurons controls movement, emotion, and memory. Mol Psychiatry 2023; 28:3994-4010. [PMID: 37833406 PMCID: PMC10905646 DOI: 10.1038/s41380-023-02286-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 09/20/2023] [Accepted: 09/29/2023] [Indexed: 10/15/2023]
Abstract
The pathogenesis of schizophrenia is believed to involve combined dysfunctions of many proteins including microtubule-associated protein 6 (MAP6) and Kv3.1 voltage-gated K+ (Kv) channel, but their relationship and functions in behavioral regulation are often not known. Here we report that MAP6 stabilizes Kv3.1 channels in parvalbumin-positive (PV+ ) fast-spiking GABAergic interneurons, regulating behavior. MAP6-/- and Kv3.1-/- mice display similar hyperactivity and avoidance reduction. Their proteins colocalize in PV+ interneurons and MAP6 deletion markedly reduces Kv3.1 protein level. We further show that two microtubule-binding modules of MAP6 bind the Kv3.1 tetramerization domain with high affinity, maintaining the channel level in both neuronal soma and axons. MAP6 knockdown by AAV-shRNA in the amygdala or the hippocampus reduces avoidance or causes hyperactivity and recognition memory deficit, respectively, through elevating projection neuron activity. Finally, knocking down Kv3.1 or disrupting the MAP6-Kv3.1 binding in these brain regions causes avoidance reduction and hyperactivity, consistent with the effects of MAP6 knockdown. Thus, disrupting this conserved cytoskeleton-membrane interaction in fast-spiking neurons causes different degrees of functional vulnerability in various neural circuits.
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Affiliation(s)
- Di Ma
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
| | - Chao Sun
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
- MCDB graduate program, The Ohio State University, Columbus, OH, USA
| | - Rahul Manne
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
| | - Tianqi Guo
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Christophe Bosc
- Univ. Grenoble Alpes, Inserm, U1216, CEA, Grenoble Institut Neurosciences, 38000, Grenoble, France
| | - Joshua Barry
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Thomas Magliery
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Annie Andrieux
- Univ. Grenoble Alpes, Inserm, U1216, CEA, Grenoble Institut Neurosciences, 38000, Grenoble, France
| | - Houzhi Li
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA
| | - Chen Gu
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA.
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA.
- MCDB graduate program, The Ohio State University, Columbus, OH, USA.
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Schuy J, Grochowski CM, Carvalho CMB, Lindstrand A. Complex genomic rearrangements: an underestimated cause of rare diseases. Trends Genet 2022; 38:1134-1146. [PMID: 35820967 PMCID: PMC9851044 DOI: 10.1016/j.tig.2022.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/12/2022] [Accepted: 06/06/2022] [Indexed: 01/24/2023]
Abstract
Complex genomic rearrangements (CGRs) are known contributors to disease but are often missed during routine genetic screening. Identifying CGRs requires (i) identifying copy number variants (CNVs) concurrently with inversions, (ii) phasing multiple breakpoint junctions incis, as well as (iii) detecting and resolving structural variants (SVs) within repeats. We demonstrate how combining cytogenetics and new sequencing methodologies is being successfully applied to gain insights into the genomic architecture of CGRs. In addition, we review CGR patterns and molecular features revealed by studying constitutional genomic disorders. These data offer invaluable lessons to individuals interested in investigating CGRs, evaluating their clinical relevance and frequency, as well as assessing their impact(s) on rare genetic diseases.
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Affiliation(s)
- Jakob Schuy
- Department of Molecular Medicine and Surgery and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | | | - Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Pacific Northwest Research Institute, Seattle, WA, USA
| | - Anna Lindstrand
- Department of Molecular Medicine and Surgery and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden.
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Chen CP, Lin SP, Chern SR, Wu PS, Chen SW, Wu FT, Town DD, Wang W. Tetrasomy of 11q13.4-q14.3 due to an intrachromosomal triplication associated with paternal uniparental isodisomy for 11q14.3-qter, intrauterine growth restriction, developmental delay, corpus callosum dysgenesis, microcephaly, congenital heart defects and facial dysmorphism. Taiwan J Obstet Gynecol 2021; 60:169-172. [PMID: 33494996 DOI: 10.1016/j.tjog.2020.11.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2020] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE We present tetrasomy of 11q13.4-q14.3 due to an intrachromosomal triplication associated with paternal isodisomy of uniparental disomy (iso-UPD) for 11q14.3-qter and multiple abnormalities. CASE REPORT A 30-year-old primigravid woman was found to have intrauterine growth restriction (IUGR) in the fetus since 28 weeks of gestation, and a 2056-g baby was delivered at 38 weeks of gestation with fetal distress. The baby postnatally manifested hypotonia, microcephaly, facial dysmorphism of micrognathia, retrognathia and low-set ears, ventricular septal defect, atrial septal defect, tricuspid regurgitation and corpus callosum dysgenesis. A single nucleotide polymorphism (SNP) array comparative genomic hybridization analysis on the DNA extracted from the peripheral blood revealed the result of arr 11q13.4q14.3 (71,567,724-89,547,851) × 4, arr 11q14.3q25 (89,466,484-134,942,626) hmz [GRCh37 (hg19)] with a 17.980-Mb triplication of 11q13.4-q14.3 encompassing the genes of GRM5 and MAP6, and loss of heterozygosity for a 45.476-Mb region of 11q14.3-qter consistent with iso-UPD for 11q14.3-qter. Polymorphic DNA marker analysis confirmed paternal iso-UPD for 11q14.3-qter. Cytogenetic analysis of the blood revealed a karyotype of 46,XY,trp(11) (q13.4q14.3). The parental karyotypes were normal. When follow-ups at age 2 years, the neonate manifested physical and psychomotor developmental delay and intellectual disability. CONCLUSION Tetrasomy 11q13.4-q14.3 may present the phenotype of IUGR, developmental delay, corpus callosum dysgenesis, microcephaly, congenital heart defects and facial dysmorphism.
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Affiliation(s)
- Chih-Ping Chen
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Medical Laboratory Science and Biotechnology, Asia University, Taichung, Taiwan.
| | - Shuan-Pei Lin
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; Department of Pediatrics, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medicine, MacKay Medical College, New Taipei City, Taiwan; Department of Early Childhood Care, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Schu-Rern Chern
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan
| | | | - Shin-Wen Chen
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Fang-Tzu Wu
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Dai-Dyi Town
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Wayseen Wang
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan
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Cuveillier C, Boulan B, Ravanello C, Denarier E, Deloulme JC, Gory-Fauré S, Delphin C, Bosc C, Arnal I, Andrieux A. Beyond Neuronal Microtubule Stabilization: MAP6 and CRMPS, Two Converging Stories. Front Mol Neurosci 2021; 14:665693. [PMID: 34025352 PMCID: PMC8131560 DOI: 10.3389/fnmol.2021.665693] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/09/2021] [Indexed: 12/21/2022] Open
Abstract
The development and function of the central nervous system rely on the microtubule (MT) and actin cytoskeletons and their respective effectors. Although the structural role of the cytoskeleton has long been acknowledged in neuronal morphology and activity, it was recently recognized to play the role of a signaling platform. Following this recognition, research into Microtubule Associated Proteins (MAPs) diversified. Indeed, historically, structural MAPs—including MAP1B, MAP2, Tau, and MAP6 (also known as STOP);—were identified and described as MT-binding and -stabilizing proteins. Extensive data obtained over the last 20 years indicated that these structural MAPs could also contribute to a variety of other molecular roles. Among multi-role MAPs, MAP6 provides a striking example illustrating the diverse molecular and cellular properties of MAPs and showing how their functional versatility contributes to the central nervous system. In this review, in addition to MAP6’s effect on microtubules, we describe its impact on the actin cytoskeleton, on neuroreceptor homeostasis, and its involvement in signaling pathways governing neuron development and maturation. We also discuss its roles in synaptic plasticity, brain connectivity, and cognitive abilities, as well as the potential relationships between the integrated brain functions of MAP6 and its molecular activities. In parallel, the Collapsin Response Mediator Proteins (CRMPs) are presented as examples of how other proteins, not initially identified as MAPs, fall into the broader MAP family. These proteins bind MTs as well as exhibiting molecular and cellular properties very similar to MAP6. Finally, we briefly summarize the multiple similarities between other classical structural MAPs and MAP6 or CRMPs.In summary, this review revisits the molecular properties and the cellular and neuronal roles of the classical MAPs, broadening our definition of what constitutes a MAP.
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Zaki MS, Eid OM, Eid MM, Mohamed AM, Sayed ISM, Abdel-Hamid MS, Abdel-Salam GMH. Bilateral Calcification of Basal Ganglia in a Patient with Duplication of Both 11q13.1q22.1 and 4q35.2 with New Phenotypic Features. Cytogenet Genome Res 2019; 159:130-136. [PMID: 31715598 DOI: 10.1159/000504075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2019] [Indexed: 11/19/2022] Open
Abstract
We report on a female patient who presented with severe intellectual disability and autistic behavior, dysmorphic features, orodental anomalies, and bilateral calcification of basal ganglia. Using a high-density oligonucleotide microarray, we have identified a de novo duplication of 11q13.1q22.1 involving the dosage sensitive genes FGF3 and FGF4, genes related to autosomal dominant disorders KMT5B, GAL, SPTBN2, and LRP5, susceptibility loci SCZD2, SLEH1, and SHANK2, mitochondrial genes NDUFV1, NDUFS8, and TMEM126B, and many loss of function genes, including PHOX2A, CLPB, MED17, B3GNT1, LIPT2, and CLPB. However, the duplication did not involve Ribonuclease H2, subunit C (RNASEH2C) which is considered to be located in the critical region for Aicardi-Goutières syndrome. In combination with the duplication at 11q13.1, a 1.849-Mb heterozygous duplication at 4q35.2 was also identified. Although this duplicated region does not contain causative genes related to brain calcification, the duplication at 4q35 was reported previously in a patient with basal ganglia calcification, coats' like retinopathy, and glomerulosclerosis. Our patient's presentation and genomic findings indicate that duplication of 4q35.2 could be a novel genetic cause of calcification of basal ganglia. Our report also underscores the clinical significance of rearrangements in 11q13.1q22.1 in the pathogenesis of basal ganglia calcification.
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Carvalho CMB, Coban-Akdemir Z, Hijazi H, Yuan B, Pendleton M, Harrington E, Beaulaurier J, Juul S, Turner DJ, Kanchi RS, Jhangiani SN, Muzny DM, Gibbs RA, Stankiewicz P, Belmont JW, Shaw CA, Cheung SW, Hanchard NA, Sutton VR, Bader PI, Lupski JR. Interchromosomal template-switching as a novel molecular mechanism for imprinting perturbations associated with Temple syndrome. Genome Med 2019; 11:25. [PMID: 31014393 PMCID: PMC6480824 DOI: 10.1186/s13073-019-0633-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 04/02/2019] [Indexed: 12/13/2022] Open
Abstract
Background Intrachromosomal triplications (TRP) can contribute to disease etiology via gene dosage effects, gene disruption, position effects, or fusion gene formation. Recently, post-zygotic de novo triplications adjacent to copy-number neutral genomic intervals with runs of homozygosity (ROH) have been shown to result in uniparental isodisomy (UPD). The genomic structure of these complex genomic rearrangements (CGRs) shows a consistent pattern of an inverted triplication flanked by duplications (DUP-TRP/INV-DUP) formed by an iterative DNA replisome template-switching mechanism during replicative repair of a single-ended, double-stranded DNA (seDNA), the ROH results from an interhomolog or nonsister chromatid template switch. It has been postulated that these CGRs may lead to genetic abnormalities in carriers due to dosage-sensitive genes mapping within the copy-number variant regions, homozygosity for alleles at a locus causing an autosomal recessive (AR) disease trait within the ROH region, or imprinting-associated diseases. Methods Here, we report a family wherein the affected subject carries a de novo 2.2-Mb TRP followed by 42.2 Mb of ROH and manifests clinical features overlapping with those observed in association with chromosome 14 maternal UPD (UPD(14)mat). UPD(14)mat can cause clinical phenotypic features enabling a diagnosis of Temple syndrome. This CGR was then molecularly characterized by high-density custom aCGH, genome-wide single-nucleotide polymorphism (SNP) and methylation arrays, exome sequencing (ES), and the Oxford Nanopore long-read sequencing technology. Results We confirmed the postulated DUP-TRP/INV-DUP structure by multiple orthogonal genomic technologies in the proband. The methylation status of known differentially methylated regions (DMRs) on chromosome 14 revealed that the subject shows the typical methylation pattern of UPD(14)mat. Consistent with these molecular findings, the clinical features overlap with those observed in Temple syndrome, including speech delay. Conclusions These data provide experimental evidence that, in humans, triplication can lead to segmental UPD and imprinting disease. Importantly, genotype/phenotype analyses further reveal how a post-zygotically generated complex structural variant, resulting from a replication-based mutational mechanism, contributes to expanding the clinical phenotype of known genetic syndromes. Mechanistically, such events can distort transmission genetics resulting in homozygosity at a locus for which only one parent is a carrier as well as cause imprinting diseases. Electronic supplementary material The online version of this article (10.1186/s13073-019-0633-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Claudia M B Carvalho
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA.
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA
| | - Hadia Hijazi
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA
| | - Bo Yuan
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA
| | | | | | | | - Sissel Juul
- Oxford Nanopore Technologies Inc, New York, NY, USA.,Oxford Nanopore Technologies Inc, San Francisco, CA, USA
| | | | | | - Shalini N Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Donna M Muzny
- 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, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA.,Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | | | - Pawel Stankiewicz
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA
| | - John W Belmont
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA.,Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Chad A Shaw
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA
| | - Sau Wai Cheung
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA
| | - Neil A Hanchard
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, USA.,Texas Children's Hospital, Houston, TX, USA
| | | | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Room 604B, Houston, TX, 77030-3498, 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, USA
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Kekis M, Deeg C, Hashimoto S, McKinney A, Erdman L, Green-Geer C, Shuss C, Hickey S, Astbury C, Pyatt RE. Partial tetrasomy 11q resulting from an intrachromosomal triplication of a 22 Mb region of chromosome 11. Am J Med Genet A 2017; 173:1056-1060. [PMID: 28328127 DOI: 10.1002/ajmg.a.38098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/28/2016] [Indexed: 02/01/2023]
Abstract
Intrachromosomal triplications are complex chromosomal rearrangements which arise during meiosis or mitosis and lead to a tetrasomic dose of the affected genomic regions. We describe a female patient harboring an intrachromosomal triplication who presented to the Genetics clinic with dysmorphic features, including telecanthus, flat facial profile, and prognathism, short stature, widely spaced nipples, multiple allergy complaints, loose bowel movements, and mild speech delay. Microarray analysis showed a copy number gain of a 22.37 Mb region of chromosome 11 between bands 11q14.1 and 11q22.1. This region contains 95 genes and seven microRNAs, none of which have been implicated in a disease resulting from increased gene dosage. FISH analysis using a probe targeted to the middle of the segment of the copy number gain yielded a pattern indicative of a tetrasomy via an intrachromosomal triplication, with three signals on the long arm of one homologue of chromosome 11 and the fourth on the other homologue. Subsequent FISH analysis showed that the middle triplicated fragment was positioned in an inverted orientation relative to the outer fragments. To investigate the mechanism by which the intrachromosomal triplication occurred, SNP microarray analysis was performed. These results were consistent with the presence of multiple haplotypes in the tetrasomic region and suggest that the intrachromosomal triplication in our patient arose in one parent during meiosis. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Mariana Kekis
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio
| | - Carol Deeg
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio
| | - Sayaka Hashimoto
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio
| | - Aimee McKinney
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio
| | - Linda Erdman
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio
| | - Cecelia Green-Geer
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio
| | - Christine Shuss
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio.,Division of Molecular and Human Genetics, Nationwide Children's Hospital, Columbus, Ohio
| | - Scott Hickey
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio.,Division of Molecular and Human Genetics, Nationwide Children's Hospital, Columbus, Ohio
| | - Caroline Astbury
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio.,Department of Pathology, The Ohio State University College of Medicine, Columbus, Ohio
| | - Robert E Pyatt
- Departmentof Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, Ohio.,Department of Pathology, The Ohio State University College of Medicine, Columbus, Ohio
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A case with concurrent duplication, triplication, and uniparental isodisomy at 1q42.12-qter supporting microhomology-mediated break-induced replication model for replicative rearrangements. Mol Cytogenet 2017; 10:15. [PMID: 28465723 PMCID: PMC5410019 DOI: 10.1186/s13039-017-0316-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 04/21/2017] [Indexed: 12/04/2022] Open
Abstract
Background Complex genomic rearrangements (CGRs) consisting of interstitial triplications in conjunction with uniparental isodisomy (isoUPD) have rarely been reported in patients with multiple congenital anomalies (MCA)/intellectual disability (ID). One-ended DNA break repair coupled with microhomology-mediated break-induced replication (MMBIR) has been recently proposed as a possible mechanism giving rise to interstitial copy number gains and distal isoUPD, although only a few cases providing supportive evidence in human congenital diseases with MCA have been documented. Case presentation Here, we report on the chromosomal microarray (CMA)-based identification of the first known case with concurrent interstitial duplication at 1q42.12-q42.2 and triplication at 1q42.2-q43 followed by isoUPD for the remainder of chromosome 1q (at 1q43-qter). In distal 1q duplication/triplication overlapping with 1q42.12-q43, variable clinical features have been reported, and our 25-year-old patient with MCA/ID presented with some of these frequently described features. Further analyses including the precise mapping of breakpoint junctions within the CGR in a sequence level suggested that the CGR found in association with isoUPD in our case is a triplication with flanking duplications, characterized as a triplication with a particularly long duplication-inverted triplication-duplication (DUP-TRP/INV-DUP) structure. Because microhomology was observed in both junctions between the triplicated region and the flanking duplicated regions, our case provides supportive evidence for recently proposed replication-based mechanisms, such as MMBIR, underlying the formation of CGRs + isoUPD implicated in chromosomal disorders. Conclusions To the best of our knowledge, this is the first case of CGRs + isoUPD observed in 1q and having DUP-TRP/INV-DUP structure with a long proximal duplication, which supports MMBIR-based model for genomic rearrangements. Molecular cytogenetic analyses using CMA containing single-nucleotide polymorphism probes with further analyses of the breakpoint junctions are recommended in cases suspected of having complex chromosomal abnormalities based on discrepancies between clinical and conventional cytogenetic findings. Electronic supplementary material The online version of this article (doi:10.1186/s13039-017-0316-6) contains supplementary material, which is available to authorized users.
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