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Brewer BJ, Dunham MJ, Raghuraman MK. A unifying model that explains the origins of human inverted copy number variants. PLoS Genet 2024; 20:e1011091. [PMID: 38175827 PMCID: PMC10766186 DOI: 10.1371/journal.pgen.1011091] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024] Open
Abstract
With the release of the telomere-to-telomere human genome sequence and the availability of both long-read sequencing and optical genome mapping techniques, the identification of copy number variants (CNVs) and other structural variants is providing new insights into human genetic disease. Different mechanisms have been proposed to account for the novel junctions in these complex architectures, including aberrant forms of DNA replication, non-allelic homologous recombination, and various pathways that repair DNA breaks. Here, we have focused on a set of structural variants that include an inverted segment and propose that they share a common initiating event: an inverted triplication with long, unstable palindromic junctions. The secondary rearrangement of these palindromes gives rise to the various forms of inverted structural variants. We postulate that this same mechanism (ODIRA: origin-dependent inverted-repeat amplification) that creates the inverted CNVs in inherited syndromes also generates the palindromes found in cancers.
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Affiliation(s)
- Bonita J. Brewer
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Maitreya J. Dunham
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - M. K. Raghuraman
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
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2
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Shimojima Yamamoto K, Tamura T, Okamoto N, Nishi E, Noguchi A, Takahashi I, Sawaishi Y, Shimizu M, Kanno H, Minakuchi Y, Toyoda A, Yamamoto T. Identification of small-sized intrachromosomal segments at the ends of INV-DUP-DEL patterns. J Hum Genet 2023; 68:751-757. [PMID: 37423943 DOI: 10.1038/s10038-023-01181-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 06/14/2023] [Accepted: 06/27/2023] [Indexed: 07/11/2023]
Abstract
The mechanism of chromosomal rearrangement associated with inverted-duplication-deletion (INV-DUP-DEL) pattern formation has been investigated by many researchers, and several possible mechanisms have been proposed. Currently, fold-back and subsequent dicentric chromosome formation has been established as non-recurrent INV-DUP-DEL pattern formation mechanisms. In the present study, we analyzed the breakpoint junctions of INV-DUP-DEL patterns in five patients using long-read whole-genome sequencing and detected 2.2-6.1 kb copy-neutral regions in all five patients. At the end of the INV-DUP-DEL, two patients exhibited chromosomal translocations, which are recognized as telomere capture, and one patient showed direct telomere healing. The remaining two patients had additional small-sized intrachromosomal segments at the end of the derivative chromosomes. These findings have not been previously reported but they may only be explained by the presence of telomere capture breakage. Further investigations are required to better understand the mechanisms underlying this finding.
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Affiliation(s)
- Keiko Shimojima Yamamoto
- Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, 162-8666, Japan
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, 162-8666, Japan
| | - Takeaki Tamura
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, 173-8610, Japan
- Division of Gene Medicine, Graduate Scholl of Medical Science, Tokyo Women's Medical University, Tokyo, 162-8666, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Izumi, 594-1101, Japan
| | - Eriko Nishi
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Izumi, 594-1101, Japan
| | - Atsuko Noguchi
- Department of Pediatrics, Akita University Graduate School of Medicine, Akita, 010-8543, Japan
| | - Ikuko Takahashi
- Department of Pediatrics, Akita University Graduate School of Medicine, Akita, 010-8543, Japan
| | - Yukio Sawaishi
- Department of Pediatrics, Akita Prefectural Center on Development and Disability, Akita, 010-0000, Japan
| | - Masaki Shimizu
- Department of Pediatrics and Developmental Biology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, 113-8519, Japan
| | - Hitoshi Kanno
- Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, 162-8666, Japan
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, 162-8666, Japan
| | - Yohei Minakuchi
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka, 411-0801, Japan
| | - Atsushi Toyoda
- Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka, 411-0801, Japan
| | - Toshiyuki Yamamoto
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, 162-8666, Japan.
- Division of Gene Medicine, Graduate Scholl of Medical Science, Tokyo Women's Medical University, Tokyo, 162-8666, Japan.
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Bonaglia MC, Fichera M, Marelli S, Romaniello R, Zuffardi O. Low-level complex mosaic with multiple cell lines affecting the 18q21.31q21.32 region in a patient with de novo 18q terminal deletion. Eur J Med Genet 2022; 65:104596. [PMID: 36064004 DOI: 10.1016/j.ejmg.2022.104596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/31/2022] [Accepted: 08/17/2022] [Indexed: 11/15/2022]
Abstract
We describe a 5-year-old girl who was diagnosed at birth with 18q de novo homogeneous deletion at G-banding karyotype. Her clinical condition, characterized by hypotonia, psychomotor retardation, short stature, deafness secondary to bilateral atresia of the external auditory canals, was in agreement with the 18q deletion syndrome though presence of coloboma of a single eye only suggested a mosaic condition as an unusual sign. By combining multiple technologies including array-CGH, FISH, and WGS, we found that the terminal deletion 18q21.32q23 (21 Mb) was in segmental mosaicism of the proximal region 18q21.31q21.32 (2.7 Mb), which showed a variable number of copies: one, two, or three, in 7, 41 and 55% of the cells respectively. Breakpoint junction analysis demonstrated the presence of an inv-dup del (18q) with a disomic segment of 4.7 kb between the inverted and non-inverted copies of the duplicated region 18q21.31q21.32. From these results, we propose that all three types of abnormal chr18 (the inv-dup del and the two 18q terminal deletions of different sizes) arisen from breaks in a dicentric mirror chromosome 18q, either in more than one embryo cell or from subsequent breaking-fusion-bridge cycles. The duplication region was with identical polymorphisms as in all non-recurrent inv-dup del rearrangements though, in contrast with most of them, the 18q abnormality was of maternal origin. Taking into account that distal 18q deletions are not rarely associated with inv-dup del(18q) cell lines, and that the non-disjunction of chromosome 18 takes place especially at maternal meiosis II rather than meiosis I, multiple rescue events starting from trisomic zygotes could be considered alternative to the postmitotic ones. From the clinical point of view, our case, as well as those of del(18q) in mosaic with the dic(18q), shows that the final phenotype is the sum of the different cell lines that acted on embryonic development with signs typical of both the 18q deletion syndrome and trisomy 18. Asymmetrical malformations, such as coloboma of the iris only in the right eye, confirm the underlying mosaicism regardless of whether it is still detectable in the blood.
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Affiliation(s)
- Maria Clara Bonaglia
- Cytogenetics Laboratory, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
| | - Marco Fichera
- Department of Biomedical and Biotechnological Sciences, Medical Genetics, University of Catania, Catania, Italy; Oasi Research Institute-IRCCS, Troina, Italy.
| | - Susan Marelli
- Medical Genetics Service, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
| | - Romina Romaniello
- Neuropsychiatry and Neurorehabilitation Unit, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
| | - Orsetta Zuffardi
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.
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Zuffardi O, Fichera M, Bonaglia MC. The embryo battle against adverse genomes: Are de novo terminal deletions the rescue of unfavorable zygotic imbalances? Eur J Med Genet 2022; 65:104532. [PMID: 35724817 DOI: 10.1016/j.ejmg.2022.104532] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 04/02/2022] [Accepted: 05/21/2022] [Indexed: 11/03/2022]
Abstract
De novo distal deletions are structural variants considered to be already present in the zygote. However, investigations especially in the prenatal setting have documented that they are often in mosaic with cell lines in which the same deleted chromosome shows different types of aberrations such as: 1) neutral copy variants with loss of heterozygosity that replace the deleted region with equivalent portions of the homologous chromosome and create distal uniparental disomy (UPD); 2) derivative chromosomes where the deleted one ends with the distal region of another chromosome or has the shape of a ring; 3) U-type mirror dicentric or inv-dup del rearrangements. Unstable dicentrics had already been entailed as causative of terminal deletions even when no trace of the reciprocal inv-dup del had been detected. To clarify the mechanism of origin of distal deletions, we examined PubMed using as keywords: complex/mosaic chromosomal deletions, distal UPD, U-type dicentrics, inv-dup del chromosomes, excluding the recurrent inv-dup del(8p)s which are known to originate by NAHR at the maternal meiosis. The literature has shown that U-type dicentrics leading to nearly complete trisomy and therefore incompatible with zygotic survival underlie many types of de novo unbalanced rearrangements, including terminal deletions. In the early embryo, the position of the postzygotic breaks of the dicentric, the different ways of acquiring telomeres by the broken portions and the selection of the most favorable cell lines in the different tissues determine the prevalence of one or the other rearrangement. Multiple lines with simple terminal deletions, inv-dup dels, unbalanced translocations and segmental UPDs can coexist in various mosaic combinations although it is rare to identify them all in the blood. Regarding the origin of the dicentric, among the 30 cases of non-recurrent inv-dup del with sufficient genotyping information, paternal origin was markedly prevalent with consistently identical polymorphisms within the duplication region, regardless of parental origin. The non-random parental origin made any postzygotic origin unlikely and suggested the occurrence of these dicentrics mainly in spermatogenesis. This study strengthens the evidence that non-recurrent de novo structural rearrangements are often secondary to the rescue of a zygotic genome incompatible with embryo survival.
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Affiliation(s)
- Orsetta Zuffardi
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.
| | - Marco Fichera
- Department of Biomedical and Biotechnological Sciences, Medical Genetics, University of Catania, Catania, Italy; Oasi Research Institute-IRCCS, Troina, Italy.
| | - Maria Clara Bonaglia
- Cytogenetics Laboratory, Scientific Institute, IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
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Burssed B, Zamariolli M, Bellucco FT, Melaragno MI. Mechanisms of structural chromosomal rearrangement formation. Mol Cytogenet 2022; 15:23. [PMID: 35701783 PMCID: PMC9199198 DOI: 10.1186/s13039-022-00600-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 05/31/2022] [Indexed: 12/31/2022] Open
Abstract
Structural chromosomal rearrangements result from different mechanisms of formation, usually related to certain genomic architectural features that may lead to genetic instability. Most of these rearrangements arise from recombination, repair, or replication mechanisms that occur after a double-strand break or the stalling/breakage of a replication fork. Here, we review the mechanisms of formation of structural rearrangements, highlighting their main features and differences. The most important mechanisms of constitutional chromosomal alterations are discussed, including Non-Allelic Homologous Recombination (NAHR), Non-Homologous End-Joining (NHEJ), Fork Stalling and Template Switching (FoSTeS), and Microhomology-Mediated Break-Induced Replication (MMBIR). Their involvement in chromoanagenesis and in the formation of complex chromosomal rearrangements, inverted duplications associated with terminal deletions, and ring chromosomes is also outlined. We reinforce the importance of high-resolution analysis to determine the DNA sequence at, and near, their breakpoints in order to infer the mechanisms of formation of structural rearrangements and to reveal how cells respond to DNA damage and repair broken ends.
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Affiliation(s)
- Bruna Burssed
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Malú Zamariolli
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Fernanda Teixeira Bellucco
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Maria Isabel Melaragno
- Genetics Division, Department of Morphology and Genetics, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
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Redaelli S, Conconi D, Sala E, Villa N, Crosti F, Roversi G, Catusi I, Valtorta C, Recalcati MP, Dalprà L, Lavitrano M, Bentivegna A. Characterization of Chromosomal Breakpoints in 12 Cases with 8p Rearrangements Defines a Continuum of Fragility of the Region. Int J Mol Sci 2022; 23:ijms23063347. [PMID: 35328767 PMCID: PMC8954119 DOI: 10.3390/ijms23063347] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 12/29/2022] Open
Abstract
Improvements in microarray-based comparative genomic hybridization technology have allowed for high-resolution detection of genome wide copy number alterations, leading to a better definition of rearrangements and supporting the study of pathogenesis mechanisms. In this study, we focused our attention on chromosome 8p. We report 12 cases of 8p rearrangements, analyzed by molecular karyotype, evidencing a continuum of fragility that involves the entire short arm. The breakpoints seem more concentrated in three intervals: one at the telomeric end, the others at 8p23.1, close to the beta-defensin gene cluster and olfactory receptor low-copy repeats. Hypothetical mechanisms for all cases are described. Our data extend the cohort of published patients with 8p aberrations and highlight the need to pay special attention to these sequences due to the risk of formation of new chromosomal aberrations with pathological effects.
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Affiliation(s)
- Serena Redaelli
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (S.R.); (G.R.); (L.D.); (M.L.)
| | - Donatella Conconi
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (S.R.); (G.R.); (L.D.); (M.L.)
- Correspondence: (D.C.); (A.B.)
| | - Elena Sala
- Medical Genetics Laboratory, Clinical Pathology Department, S. Gerardo Hospital, 20900 Monza, Italy; (E.S.); (N.V.); (F.C.)
| | - Nicoletta Villa
- Medical Genetics Laboratory, Clinical Pathology Department, S. Gerardo Hospital, 20900 Monza, Italy; (E.S.); (N.V.); (F.C.)
| | - Francesca Crosti
- Medical Genetics Laboratory, Clinical Pathology Department, S. Gerardo Hospital, 20900 Monza, Italy; (E.S.); (N.V.); (F.C.)
| | - Gaia Roversi
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (S.R.); (G.R.); (L.D.); (M.L.)
- Medical Genetics Laboratory, Clinical Pathology Department, S. Gerardo Hospital, 20900 Monza, Italy; (E.S.); (N.V.); (F.C.)
| | - Ilaria Catusi
- Medical Cytogenetics Laboratory, Istituto Auxologico Italiano IRCCS, 20095 Cusano Milanino, Italy; (I.C.); (C.V.); (M.P.R.)
| | - Chiara Valtorta
- Medical Cytogenetics Laboratory, Istituto Auxologico Italiano IRCCS, 20095 Cusano Milanino, Italy; (I.C.); (C.V.); (M.P.R.)
| | - Maria Paola Recalcati
- Medical Cytogenetics Laboratory, Istituto Auxologico Italiano IRCCS, 20095 Cusano Milanino, Italy; (I.C.); (C.V.); (M.P.R.)
| | - Leda Dalprà
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (S.R.); (G.R.); (L.D.); (M.L.)
- Medical Genetics Laboratory, Clinical Pathology Department, S. Gerardo Hospital, 20900 Monza, Italy; (E.S.); (N.V.); (F.C.)
| | - Marialuisa Lavitrano
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (S.R.); (G.R.); (L.D.); (M.L.)
| | - Angela Bentivegna
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy; (S.R.); (G.R.); (L.D.); (M.L.)
- Correspondence: (D.C.); (A.B.)
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Target enrichment long-read sequencing with adaptive sampling can determine the structure of the small supernumerary marker chromosomes. J Hum Genet 2022; 67:363-368. [PMID: 35027654 DOI: 10.1038/s10038-021-01004-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 11/05/2021] [Accepted: 12/04/2021] [Indexed: 12/23/2022]
Abstract
Structural analysis of small supernumerary marker chromosomes (sSMCs) has revealed that many have complex structures. Structural analysis of sSMCs by whole genome sequencing using short-read sequencers is challenging however because most present with a low level of mosaicism and consist of a small region of the involved chromosome. In this present study, we applied adaptive sampling using nanopore long-read sequencing technology to enrich the target region and thereby attempted to determine the structure of two sSMCs with complex structural rearrangements previously revealed by cytogenetic microarray. In adaptive sampling, simple specification of the target region in the FASTA file enables to identify whether or not the sequencing DNA is included in the target, thus promoting efficient long-read sequencing. To evaluate the target enrichment efficiency, we performed conventional pair-end short-read sequencing in parallel. Sequencing with adaptive sampling achieved a target enrichment at about a 11.0- to 11.5-fold higher coverage rate than conventional pair-end sequencing. This enabled us to quickly identify all breakpoint junctions and determine the exact sSMC structure as a ring chromosome. In addition to the microhomology and microinsertion at the junctions, we identified inverted repeat structure in both sSMCs, suggesting the common generation mechanism involving replication impairment. Adaptive sampling is thus an easy and beneficial method of determining the structures of complex chromosomal rearrangements.
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Papenhausen PR, Kelly CA, Harris S, Caldwell S, Schwartz S, Penton A. Clinical significance and mechanisms associated with segmental UPD. Mol Cytogenet 2021; 14:38. [PMID: 34284807 PMCID: PMC8290618 DOI: 10.1186/s13039-021-00555-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 06/22/2021] [Indexed: 11/14/2022] Open
Abstract
Whole chromosome uniparental disomy (UPD) has been well documented with mechanisms largely understood. However, the etiology of segmental limited UPD (segUPD) is not as clear. In a 10-year period of confirming (> 300) cases of whole chromosome UPD, we identified 86 segmental cases in both prenatal and postnatal samples. Thirty-two of these cases showed mosaic segmental UPD at 11p due to somatic selection associated with Beckwith–Wiedemann syndrome. This study focuses on apparent mechanisms associated with the remaining cases, many of which appear to represent corrections of genomic imbalance such as deletions and derivative chromosomes. In some cases, segmental UPD was associated with the generation of additional genomic imbalance while in others it apparently resulted in restoration of euploidy. Multiple tests utilizing noninvasive prenatal testing (NIPT), chorionic villus sampling (CVS) and amniotic fluid samples from the same pregnancy revealed temporal evidence of correction and a “hotspot” at 1p. Although in many cases the genomic imbalance was dosage “repaired” in the analyzed tissue, clinical effects could be sustained due to early developmental effects of the original imbalance or due to its continued existence in other tissues. In addition, if correction did not occur in the gametes there would be recurrence risks for the offspring of those individuals. Familial microarray allele patterns are presented that differentiate lack of gamete correction from somatic derived gonadal mosaicism. These results suggest that the incidence of segUPD mediated correction is underestimated and may explain the etiology of some clinical phenotypes which are undetected by routine microarray analysis and many exome sequencing studies.
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Affiliation(s)
- Peter R Papenhausen
- Cytogenetics Department, Laboratory Corporation of America, Research Triangle Park, NC, 27709, USA
| | - Carla A Kelly
- Cytogenetics Department, Laboratory Corporation of America, Research Triangle Park, NC, 27709, USA
| | - Samuel Harris
- Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - Samantha Caldwell
- Cytogenetics Department, Laboratory Corporation of America, Research Triangle Park, NC, 27709, USA
| | - Stuart Schwartz
- Cytogenetics Department, Laboratory Corporation of America, Research Triangle Park, NC, 27709, USA
| | - Andrea Penton
- Cytogenetics Department, Laboratory Corporation of America, Research Triangle Park, NC, 27709, USA.
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Catusi I, Garzo M, Capra AP, Briuglia S, Baldo C, Canevini MP, Cantone R, Elia F, Forzano F, Galesi O, Grosso E, Malacarne M, Peron A, Romano C, Saccani M, Larizza L, Recalcati MP. 8p23.2-pter Microdeletions: Seven New Cases Narrowing the Candidate Region and Review of the Literature. Genes (Basel) 2021; 12:genes12050652. [PMID: 33925474 PMCID: PMC8146486 DOI: 10.3390/genes12050652] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 12/11/2022] Open
Abstract
To date only five patients with 8p23.2-pter microdeletions manifesting a mild-to-moderate cognitive impairment and/or developmental delay, dysmorphisms and neurobehavioral issues were reported. The smallest microdeletion described by Wu in 2010 suggested a critical region (CR) of 2.1 Mb including several genes, out of which FBXO25, DLGAP2, CLN8, ARHGEF10 and MYOM2 are the main candidates. Here we present seven additional patients with 8p23.2-pter microdeletions, ranging from 71.79 kb to 4.55 Mb. The review of five previously reported and nine Decipher patients confirmed the association of the CR with a variable clinical phenotype characterized by intellectual disability/developmental delay, including language and speech delay and/or motor impairment, behavioral anomalies, autism spectrum disorder, dysmorphisms, microcephaly, fingers/toes anomalies and epilepsy. Genotype analysis allowed to narrow down the 8p23.3 candidate region which includes only DLGAP2, CLN8 and ARHGEF10 genes, accounting for the main signs of the broad clinical phenotype associated to 8p23.2-pter microdeletions. This region is more restricted compared to the previously proposed CR. Overall, our data favor the hypothesis that DLGAP2 is the actual strongest candidate for neurodevelopmental/behavioral phenotypes. Additional patients will be necessary to validate the pathogenic role of DLGAP2 and better define how the two contiguous genes, ARHGEF10 and CLN8, might contribute to the clinical phenotype.
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Affiliation(s)
- Ilaria Catusi
- Istituto Auxologico Italiano, IRCCS, Laboratory of Medical Cytogenetics and Molecular Genetics, 20145 Milan, Italy
| | - Maria Garzo
- Istituto Auxologico Italiano, IRCCS, Laboratory of Medical Cytogenetics and Molecular Genetics, 20145 Milan, Italy
| | - Anna Paola Capra
- Department of Biomedical, Dental, Morphological and Functional Imaging Sciences, University of Messina, 98100 Messina, Italy
| | - Silvana Briuglia
- Department of Biomedical, Dental, Morphological and Functional Imaging Sciences, University of Messina, 98100 Messina, Italy
| | - Chiara Baldo
- UOC Laboratorio di Genetica Umana, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy
| | - Maria Paola Canevini
- Child Neuropsychiatry Unit-Epilepsy Center, Department of Health Sciences, ASST Santi Paolo e Carlo, San Paolo Hospital, Università Degli Studi di Milano, 20142 Milan, Italy
| | - Rachele Cantone
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, 10126 Turin, Italy
| | - Flaviana Elia
- Unit of Psychology, Oasi Research Institute-IRCCS, 94018 Troina, Italy
| | - Francesca Forzano
- Clinical Genetics Department, Guy's & St Thomas' NHS Foundation Trust, London SE1 9RT, UK
| | - Ornella Galesi
- Laboratory of Medical Genetics, Oasi Research Institute-IRCCS, 94018 Troina, Italy
| | - Enrico Grosso
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, 10126 Turin, Italy
| | - Michela Malacarne
- UOC Laboratorio di Genetica Umana, IRCCS Istituto Giannina Gaslini, 16147 Genova, Italy
| | - Angela Peron
- Child Neuropsychiatry Unit-Epilepsy Center, Department of Health Sciences, ASST Santi Paolo e Carlo, San Paolo Hospital, Università Degli Studi di Milano, 20142 Milan, Italy
- Human Pathology and Medical Genetics, ASST Santi Paolo e Carlo, San Paolo Hospital, 20142 Milan, Italy
- Division of Medical Genetics, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Corrado Romano
- Unit of Pediatrics and Medical Genetics, Oasi Research Institute-IRCCS, 94018 Troina, Italy
| | - Monica Saccani
- Child Neuropsychiatry Unit-Epilepsy Center, Department of Health Sciences, ASST Santi Paolo e Carlo, San Paolo Hospital, Università Degli Studi di Milano, 20142 Milan, Italy
| | - Lidia Larizza
- Istituto Auxologico Italiano, IRCCS, Laboratory of Medical Cytogenetics and Molecular Genetics, 20145 Milan, Italy
| | - Maria Paola Recalcati
- Istituto Auxologico Italiano, IRCCS, Laboratory of Medical Cytogenetics and Molecular Genetics, 20145 Milan, Italy
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