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Sahajpal N, Ziats C, Chaubey A, DuPont BR, Abidi F, Schwartz CE, Stevenson RE. Clinical findings in individuals with duplication of genes associated with X-linked intellectual disability. Clin Genet 2024; 105:173-184. [PMID: 37899624 DOI: 10.1111/cge.14445] [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: 08/09/2023] [Revised: 09/25/2023] [Accepted: 10/13/2023] [Indexed: 10/31/2023]
Abstract
Duplication of all genes associated with X-linked intellectual disability (XLID) have been reported but the majority of the duplications include more than one XLID gene. It is exceptional for whole XLID gene duplications to cause the same phenotype as sequence variants or deletions of the same gene. Duplication of PLP1, the gene associated with Pelizaeus-Merzbacher syndrome, is the most notable duplication of this type. More commonly, duplication of XLID genes results in very different phenotypes than sequence alterations or deletions. Duplication of MECP2 is widely recognized as a duplication of this type, but a number of others exist. The phenotypes associated with gene duplications are often milder than those caused by deletions and sequence variants. Among some duplications that are clinically significant, marked skewing of X-inactivation in female carriers has been observed. This report describes the phenotypic consequences of duplication of 22 individual XLID genes, of which 10 are described for the first time.
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Affiliation(s)
- Nikhil Sahajpal
- Diagnostic Laboratories, Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Catherine Ziats
- Genetics Department, Shodair Children's Hospital, Helena, Montana, USA
| | - Alka Chaubey
- Clinical and Scientific Affairs, Bionano Genomics, San Diego, California, USA
| | - Barbara R DuPont
- Diagnostic Laboratories, Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Fatima Abidi
- Diagnostic Laboratories, Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Charles E Schwartz
- Department of Pediatrics and Human Development, Michigan State University, Grand Rapids, Michigan, USA
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Tilemis FN, Marinakis NM, Veltra D, Svingou M, Kekou K, Mitrakos A, Tzetis M, Kosma K, Makrythanasis P, Traeger-Synodinos J, Sofocleous C. Germline CNV Detection through Whole-Exome Sequencing (WES) Data Analysis Enhances Resolution of Rare Genetic Diseases. Genes (Basel) 2023; 14:1490. [PMID: 37510394 PMCID: PMC10379589 DOI: 10.3390/genes14071490] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/14/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
Whole-Exome Sequencing (WES) has proven valuable in the characterization of underlying genetic defects in most rare diseases (RDs). Copy Number Variants (CNVs) were initially thought to escape detection. Recent technological advances enabled CNV calling from WES data with the use of accurate and highly sensitive bioinformatic tools. Amongst 920 patients referred for WES, 454 unresolved cases were further analysed using the ExomeDepth algorithm. CNVs were called, evaluated and categorized according to ACMG/ClinGen recommendations. Causative CNVs were identified in 40 patients, increasing the diagnostic yield of WES from 50.7% (466/920) to 55% (506/920). Twenty-two CNVs were available for validation and were all confirmed; of these, five were novel. Implementation of the ExomeDepth tool promoted effective identification of phenotype-relevant and/or novel CNVs. Among the advantages of calling CNVs from WES data, characterization of complex genotypes comprising both CNVs and SNVs minimizes cost and time to final diagnosis, while allowing differentiation between true or false homozygosity, as well as compound heterozygosity of variants in AR genes. The use of a specific algorithm for calling CNVs from WES data enables ancillary detection of different types of causative genetic variants, making WES a critical first-tier diagnostic test for patients with RDs.
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Affiliation(s)
- Faidon-Nikolaos Tilemis
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Nikolaos M Marinakis
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
- Research University Institute for the Study and Prevention of Genetic and Malignant Disease of Childhood, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Danai Veltra
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
- Research University Institute for the Study and Prevention of Genetic and Malignant Disease of Childhood, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Maria Svingou
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Kyriaki Kekou
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Anastasios Mitrakos
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
- Research University Institute for the Study and Prevention of Genetic and Malignant Disease of Childhood, St. Sophia's Children's Hospital, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Maria Tzetis
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Konstantina Kosma
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Periklis Makrythanasis
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
- Department of Genetic Medicine and Development, Medical School, University of Geneva, 1211 Geneva, Switzerland
- Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece
| | - Joanne Traeger-Synodinos
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Christalena Sofocleous
- Laboratory of Medical Genetics, St. Sophia's Children's Hospital, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
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Sakka R, Abdelhedi F, Sellami H, Pichon B, Lajmi Y, Mnif M, Kebaili S, Derbel R, Kamoun H, Gdoura R, Delbaere A, Desir J, Abramowicz M, Vialard F, Dupont JM, Ammar-Keskes L. An unusual familial Xp22.12 microduplication including EIF1AX: A novel candidate dosage-sensitive gene for premature ovarian insufficiency. Eur J Med Genet 2022; 65:104613. [PMID: 36113757 DOI: 10.1016/j.ejmg.2022.104613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 07/22/2022] [Accepted: 09/09/2022] [Indexed: 11/19/2022]
Abstract
We report on the results of array-CGH and Whole exome sequencing (WES) studies carried out in a Tunisian family with 46,XX premature ovarian insufficiency (POI). This study has led to the identification of a familial Xp22.12 tandem duplication with a size of 559.4 kb, encompassing only three OMIM genes (RPS6KA3, SH3KBP1and EIF1AX), and a new heterozygous variant in SPIDR gene: NM_001080394.3:c.1845_1853delTATAATTGA (p.Ile616_Asp618del) segregating with POI. Increased mRNA expression levels were detected for SH3KBP1 and EIF1AX, while a normal transcript level for RPS6KA3 was detected in the three affected family members, explaining the absence of intellectual disability (ID). To the best of our knowledge, this is the first duplication involving the Xp22.12 region, reported in a family without ID, but rather with secondary amenorrhea (SA) and female infertility. As EIF1AX is a regulatory gene escaping X-inactivation, which has an extreme dosage sensitivity and highly expressed in the ovary, we suggest that this gene might be a candidate gene for ovarian function. Homozygous nonsense pathogenic variants of SPIDR gene have been reported in familial cases in POI. It has been suggested that chromosomal instability associated with SPIDR molecular defects supports the role of SPIDR protein in double-stranded DNA damage repair in vivo in humans and its causal role in POI. In this family, the variant (p.Ile616_Asp618del), present in a heterozygous state, is located in the domain that interacts with BLM and might disrupt the BLM binding ability of SPIDR protein. These findings strengthen the hypothesis that the additional effect of this variant could lead to POI in this family. Although the work represents the first evidence that EIF1AX duplication might be responsible for POI through its over-expression, further functional studies are needed to clarify and prove EIF1AX involvement in POI phenotype.
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Affiliation(s)
- Rim Sakka
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia; Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Fatma Abdelhedi
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia; Medical Genetics Department, Hedi Chaker Hospital, Sfax, Tunisia.
| | - Hanen Sellami
- Water Researches and Technologies Center (CERTE), University of Carthage, Tourist Road Soliman, Nabeul, Tunisia; Toxicology, Environmental Microbiology and Health Research Laboratory (LR17ES06), Faculty of Sciences of Sfax, University of Sfax, Tunisia
| | - Bruno Pichon
- Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Yosra Lajmi
- Cytogenetics Department, Cochin Hospital, Assistance Publique des Hôpitaux de Paris, Sorbonne Paris Cité, Paris Descartes University, Medical School, Paris, France
| | - Mouna Mnif
- Department of Endocrinology, Hedi Chaker Hospital, Sfax, Tunisia
| | - Sahbi Kebaili
- Department of Gynecology, HediChaker Hospital, Sfax, Tunisia
| | - Rihab Derbel
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia
| | - Hassen Kamoun
- Medical Genetics Department, Hedi Chaker Hospital, Sfax, Tunisia
| | - Radhouane Gdoura
- Toxicology, Environmental Microbiology and Health Research Laboratory (LR17ES06), Faculty of Sciences of Sfax, University of Sfax, Tunisia
| | - Anne Delbaere
- Fertility Clinic, Department of Gynecology and Obstetrics, Erasme Hospital, UniversitéLibre de Bruxelles, Brussels, Belgium
| | - Julie Desir
- Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Marc Abramowicz
- Center of Medical Genetics, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - François Vialard
- Genetics Department, CHI Poissy St Germain-en-Laye, F-78300, Poissy, France; RHuMA Team, UMR-BREED, INRAE-UVSQ-ENVA, UFR-SVS, F-78180, Montigny le Bretonneux, France
| | - Jean-Michel Dupont
- Cytogenetics Department, Cochin Hospital, Assistance Publique des Hôpitaux de Paris, Sorbonne Paris Cité, Paris Descartes University, Medical School, Paris, France
| | - Leila Ammar-Keskes
- Human Molecular Genetics Laboratory, Faculty of Medicine of Sfax, University of Sfax, Tunisia
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Yanagishita T, Imaizumi T, Yamamoto-Shimojima K, Yano T, Okamoto N, Nagata S, Yamamoto T. Breakpoint junction analysis for complex genomic rearrangements with the caldera volcano-like pattern. Hum Mutat 2020; 41:2119-2127. [PMID: 32906213 DOI: 10.1002/humu.24108] [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] [Received: 06/21/2020] [Revised: 08/25/2020] [Accepted: 09/06/2020] [Indexed: 12/16/2022]
Abstract
Chromosomal triplications can be classified into recurrent and nonrecurrent triplications. Most of the nonrecurrent triplications are embedded in duplicated segments, and duplication-inverted triplication-duplication (DUP-TRP/INV-DUP) has been established as one of the mechanisms of triplication. This study aimed to reveal the underlying mechanism of the TRP-DUP-TRP pattern of chromosomal aberrations, in which the appearance of moving averages obtained through array-based comparative genomic hybridization analysis is similar to the shadows of the caldera volcano-like pattern, which were first identified in two patients with neurodevelopmental disabilities. For this purpose, whole-genome sequencing using long-read Nanopore sequencing was carried out to confirm breakpoint junctions. Custom array analysis and Sanger sequencing were also used to detect all breakpoint junctions. As a result, the TRP-DUP-TRP pattern consisted of only two patterns of breakpoint junctions in both patients. In patient 1, microhomologies were identified in breakpoint junctions. In patient 2, more complex architectures with insertional segments were identified. Thus, replication-based mechanisms were considered as a mechanism of the TRP-DUP-TRP pattern.
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Affiliation(s)
- Tomoe Yanagishita
- Department of Pediatrics, Tokyo Women's Medical University, Tokyo, Japan.,Department of Genomic Medicine, Tokyo Women's Medical University, Tokyo, Japan
| | - Taichi Imaizumi
- Department of Genomic Medicine, Tokyo Women's Medical University, Tokyo, Japan.,Department of Pediatrics, St. Marianna University School of Medicine, Kawasaki, Japan
| | | | - Tamami Yano
- Department of Pediatrics, Akita University, Akita, Japan
| | - Nobuhiko Okamoto
- Department of Medical Genetics, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Satoru Nagata
- Department of Pediatrics, Tokyo Women's Medical University, Tokyo, Japan
| | - Toshiyuki Yamamoto
- Department of Pediatrics, Tokyo Women's Medical University, Tokyo, Japan.,Department of Genomic Medicine, Tokyo Women's Medical University, Tokyo, Japan.,Department of Pediatrics, St. Marianna University School of Medicine, Kawasaki, Japan.,Institute for Integrated Medical Sciences, Tokyo Women's Medical University, Tokyo, Japan
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