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Zhuang J, Zhang N, Wang J, Jiang Y, Zhang H, Chen C. Initial clinical and molecular investigation of 20q13.33 microdeletion with 17q25.3/14q32.31q32.33 microduplication in Chinese pediatric patients. Mol Genet Genomic Med 2024; 12:e2429. [PMID: 38553934 PMCID: PMC10980884 DOI: 10.1002/mgg3.2429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 03/01/2024] [Accepted: 03/19/2024] [Indexed: 04/02/2024] Open
Abstract
BACKGROUND Limited research has been conducted regarding the elucidation of genotype-phenotype correlations within the 20q13.33 region. The genotype-phenotype association of 20q13.33 microdeletion remains inadequately understood. In the present study, two novel cases of 20q13.33 microdeletion were introduced, with the objective of enhancing understanding of the genotype-phenotype relationship. METHODS Two unrelated patients with various abnormal clinical phenotypes from Fujian province Southeast China were enrolled in the present study. Karyotype analysis and chromosomal microarray analysis (CMA) were performed to investigate chromosomal abnormalities and copy number variants. RESULTS The results of high-resolution G-banding karyotype analysis elicited a 46,XY,der(20)add(20)(q13.3) in Patient 1. This patient exhibited various clinical manifestations, such as global developmental delay, intellectual disability, seizures, and other congenital diseases. Subsequently, a 1.0-Mb deletion was identified in the 20q13.33 region alongside a 5.2-Mb duplication in the 14q32.31q32.33 region. In Patient 2, CMA results revealed a 1.8-Mb deletion in the 20q13.33 region with a 4.8-Mb duplication of 17q25.3. The patient exhibited additional abnormal clinical features, including micropenis, congenital heart disease, and a distinctive crying pattern characterized by a crooked mouth. CONCLUSION In the present study, for the first time, an investigation was conducted into two novel cases of 20q13.33 microdeletion with microduplications in the 17q25.3 and 14q32.31q32.33 regions in the Chinese population. The presence of micropenis may be attributed to the 20q13.33 microdeletion, potentially expanding the phenotypic spectrum associated with this deletion.
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Affiliation(s)
- Jianlong Zhuang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Na Zhang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Junyu Wang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Yuying Jiang
- Prenatal Diagnosis Center, Quanzhou Women's and Children's HospitalQuanzhouChina
| | - Hegan Zhang
- Department of GynecologyQuanzhou Women's and Children's HospitalQuanzhouChina
| | - Chunnuan Chen
- Department of NeurologyThe Second Affiliated Hospital of Fujian Medical UniversityQuanzhouChina
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Flowers NJ, Burgess T, Giouzeppos O, Shi G, Love CJ, Hunt CE, Scarff KL, Archibald AD, Pertile MD. Genome-wide noninvasive prenatal screening for carriers of balanced reciprocal translocations. Genet Med 2020; 22:1944-1955. [PMID: 32807973 DOI: 10.1038/s41436-020-0930-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 07/26/2020] [Accepted: 07/27/2020] [Indexed: 12/27/2022] Open
Abstract
PURPOSE Balanced reciprocal translocation carriers are at increased risk of producing gametes with unbalanced forms of the translocation leading to miscarriage, fetal anomalies, and birth defects. We sought to determine if genome-wide cell-free DNA based noninvasive prenatal screening (gw-NIPS) could provide an alternative to prenatal diagnosis for carriers of these chromosomal rearrangements. METHODS This pilot series comprises a retrospective analysis of gw-NIPS and clinical outcome data from 42 singleton pregnancies where one parent carried a balanced reciprocal translocation. Gw-NIPS was performed between August 2015 and March 2018. Inclusion criteria required at least one translocation segment to be ≥15 Mb in size. RESULTS Forty samples (95%) returned an informative result; 7 pregnancies (17.5%) were high risk for an unbalanced translocation and confirmed after diagnostic testing. The remaining 33 informative samples were low risk and confirmed after diagnostic testing or normal newborn physical exam. Test sensitivity of 100% (95% confidence interval [CI]: 64.6-100%) and specificity of 100% (95% CI: 89.6-100%) were observed for this pilot series. CONCLUSION We demonstrate that gw-NIPS is a potential option for a majority of reciprocal translocation carriers. Further confirmation of this methodology could lead to adoption of this noninvasive alternative.
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Affiliation(s)
- Nicola Jane Flowers
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Trent Burgess
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Olivia Giouzeppos
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Grace Shi
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Clare Jane Love
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Clare Elizabeth Hunt
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Katrina Louise Scarff
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia
| | - Alison Dalton Archibald
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia
| | - Mark Domenic Pertile
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Parkville, VIC, Australia. .,Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.
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Si N, Meng X, Zhao Z, Xia W, Zhang X. A 105 kb interstitial insertion in the Xq27.1 palindrome from pseudoautosomal region PAR1 causes a novel X-linked recessive compound phenotype. J Transl Med 2019; 17:138. [PMID: 31036090 PMCID: PMC6489244 DOI: 10.1186/s12967-019-1887-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 04/17/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genomic disorders present a wide spectrum of unrelated clinical entities that result from genomic rearrangements. Interstitial insertions requiring three points of breakage are rare genomic rearrangement events. The pseudoautosomal region PAR1, homologous between the Xp22 and Yp11 loci, has a high crossover and recombination rate. A 180 bp human-specific palindrome at Xq27.1 appears to be a hotspot for genomic rearrangement, and several genetic diseases/phenotypes associated with Xq27.1 palindrome-driven genomic rearrangement have been reported. Here we investigate a Chinese family with an extremely rare X-linked compound phenotype that remains undiagnosed. We attempt to identify underlying genetic causes by an integrated genome analysis. METHODS A five-generation Chinese family with a distinct X-linked compound phenotype was recruited. Peripheral blood samples were collected and genomic DNA was extracted. Systemic physical and lab examinations were performed to evaluate the phenotype. An integrated genomic analysis was performed. Genotyping and linkage analysis were conducted to map the disease locus. Whole exome sequencing was performed to detect mutations in coding region. Whole genome sequencing was used to detect single nucleotide variations, small insertions, small deletions, or large structural variations. Copy number variation scanning was also performed on the genome scale. Interstitial insertion was confirmed by gap-PCR and quantitative-PCR, and breakpoint junctions were identified by genome walking and direct sequencing. Expression of products of genes nearby to the Xq27.1 palindrome was measured in peripheral blood from patients and unrelated controls via quantitative-PCR. RESULTS The identified compound phenotype of genu varum, cubitus valgus, and everted lipsdoes not match any reported clinical entities. Fine mapping and linkage analysis identified a candidate interval of 4 Mb on the X chromosome. No potential coding region mutations were detected. A 105 kb genomic fragment of PAR1 containing no coding genes was duplicated and inserted into the center of a human-specific palindrome at Xq27.1. The interstitial insertion fully cosegregated with the family phenotype. No expression of FGF13 or SOX3 was detected in peripheral blood from the proband or unrelated controls. CONCLUSION We report an extremely rare phenotype associated with an infrequently-seen genomic rearrangement. The novel compound phenotype is X-linked and characterized by genu varum, cubitus valgus, and everted lips. A 105 kb interstitial insertion of a PAR1 fragment into the Xq27.1 palindrome is associated with the phenotype in the family. The present study identified the underlying genetic cause of the phenotype, expanding the spectrum of known human-specific Xq27.1 palindrome insertion events and associated phenotypes.
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Affiliation(s)
- Nuo Si
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Xiaolu Meng
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China
| | - Zhen Zhao
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China
| | - Weibo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, 100730, China.
| | - Xue Zhang
- McKusick-Zhang Center for Genetic Medicine, State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, 100005, China.
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Two familial intrachromosomal insertions with maternal dup(6)(p22.3p25.3) or dup(2)(q24.2q32.1) in recombinant offspring. Clin Dysmorphol 2017; 26:209-216. [PMID: 28737552 DOI: 10.1097/mcd.0000000000000191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this study, we describe two patients with a recombinant chromosome secondary to a maternal intrachromosomal insertion. Patient 1 was a girl with dup(6)(p22.3p25.3). Patient 2 was a boy with dup(2)(q24.2q32.1). Both familial rearrangements were characterized by means of GTG-bands, fluorescence in-situ hybridization, and comparative genomic hybridization microarray analyses. Patient 1 had an ∼23 Mb gain that involved the bands 6p22.3-6p25.3. Patient 2 had an ∼23 Mb gain (cytobands 2q24.2-2q32.1) and a further ∼1.9 Mb gain of 2p16.2-p16.3. The phenotype of each patient was in agreement with the typical 6p duplication or 2q24.2q32.1 duplication syndrome. The compound macular lesion in patient 1 suggests that retinal anomalies may be a part of the 6p trisomy phenotype. Among the 70 intrachromosomal insertions compiled here (including 68 from the literature), four were submicroscopic unbalanced insertions inherited from a balanced carrier and 66 were detectable on banded chromosomes (with or without array comparative genomic hybridization or other high-resolution assessment) and therefore spanned at least 5 Mb. Pericentric insertions are found in most chromosomes, whereas the paracentric ones are mainly observed in large and medium chromosome arms. That the former outnumber the latter in almost a 2 : 1 ratio appears to be related to the technique of diagnosis, size of the insertion, and size of the involved chromosome. Regardless of the apparent excess of carrier mothers, carriers of an intrachromosomal insertion beget almost twice as many children with a duplication than with a deletion.
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Jones CA, Kolomietz E, Maire G, Vlasschaert M, Joseph-George AM, Myles-Reid D, Chong K, Chitayat D, Arthur R. PGD for a carrier of an intrachromosomal insertion using aCGH. Syst Biol Reprod Med 2014; 60:377-82. [PMID: 25247722 DOI: 10.3109/19396368.2014.962710] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Intrachromosomal insertions are rare and difficult to diagnose. However, making the correct diagnosis is critical for genetic risk assessment, and prenatal and preimplantation genetic diagnosis outcomes. We present a case of preimplantation genetic diagnosis (PGD) using array comparative genomic hybridization (aCGH) following trophectoderm biopsy of embryos created after in vitro fertilization for a carrier of an intrachromosomal insertion on chromosome 1 [46,XX, ins(1)(q44q23q32.1)]. The PGD analysis of 6 blastocysts demonstrated 67% unbalanced embryos. No pregnancy was achieved after the transfer of 2 euploid embryos. To the best of our knowledge, this is the first reported case of PGD using aCGH following trophectoderm biopsy for a carrier of an intrachromosomal insertion.
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Affiliation(s)
- Claire Ann Jones
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynaecology, Mount Sinai Hospital, University of Toronto
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Allen NM, Mannion M, Conroy J, Lynch SA, Shahwan A, Lynch B, King MD. The variable phenotypes of KCNQ-related epilepsy. Epilepsia 2014; 55:e99-105. [DOI: 10.1111/epi.12715] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Nicholas M. Allen
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Maria Mannion
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Judith Conroy
- Academic Centre on Rare Diseases; School of Medicine and Medical Science; University College; Dublin Ireland
| | - Sally A. Lynch
- Academic Centre on Rare Diseases; School of Medicine and Medical Science; University College; Dublin Ireland
- Department of Clinical Genetics; Children's University Hospital; Temple St. Dublin Ireland
| | - Amre Shahwan
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Bryan Lynch
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
| | - Mary D. King
- Department of Paediatric Neurology & Clinical Neurophysiology; Children's University Hospital; Dublin Ireland
- Academic Centre on Rare Diseases; School of Medicine and Medical Science; University College; Dublin Ireland
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Batanian JR, Braddock SR, Christensen K, Knutsen AP. Combined immunodeficiency in a 3-year-old boy with 16p11.2 and 20p12.2-11.2 chromosomal duplications. Am J Med Genet A 2013; 164A:535-41. [PMID: 24311374 DOI: 10.1002/ajmg.a.36305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 09/26/2013] [Indexed: 11/07/2022]
Abstract
We report for the first time on a 3-year-old boy with paternally inherited 212.85 kb-16p11.2 and 7.8 Mb-20p12.2-11.23 interstitial microduplications associated with having congenital cardiac defect, dysmorphic facial features, and combined T-, B-, and NK cell immunodeficiency. In addition the 7.8 Mb-20p12.2-11.23 microduplication is unique showing novel breakpoints among all partial trisomy/duplication 20p reported to date, narrowing down the critical region for trisomy 20p syndrome.
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Affiliation(s)
- Jacqueline R Batanian
- Division of Molecular Cytogenetics Laboratory, Saint Louis University Medical Center, St. Louis, Missouri; Department of Pediatrics, Saint Louis University Medical Center, St. Louis, Missouri
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Manolakos E, Vetro A, Papadopoulou E, Kefalas K, Lagou M, Thomaidis L, Peitsidis P, Sifakis S, Divane A, Ziegler M, Liehr T, Zuffardi O, Papoulidis I. Partial trisomy 2p and partial monosomy 2q arising from a paternal intrachromosomal 2q-into-2p between-arm insertion and paracentric inversion: molecular cytogenetic characterization of a four-break rearrangement. Cytogenet Genome Res 2013; 140:12-20. [PMID: 23652918 DOI: 10.1159/000350868] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2012] [Indexed: 11/19/2022] Open
Abstract
We report on a 26-month-old boy with an interstitial duplication of 2p22.3p22.2 and an interstitial deletion of 2q14.1q21.2. The abnormality was derived from his father having a balanced paracentric inversion and pericentric insertion. The deletion in the child was identified by cytogenetic analysis and characterized in more detail by molecular cytogenetics and array comparative genomic hybridization. The latter revealed a 20-Mb deletion in the long arm and a 5.6-Mb duplication in the short arm of chromosome 2. Fluorescence in situ hybridization in paternal chromosomes characterized an intrachromosomal insertion of 2q14.1q21.2 into 2p23; additionally a paracentric inversion of 2p13p23 was observed. The boy with the unbalanced karyotype suffered from severe psychomotor retardation, thrombophilia due to protein C deficiency, and hypertrophic cardiomyopathy and also had phenotypic abnormalities. Most of these features have previously been described in individuals with interstitial deletion of 2q14.1.
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Affiliation(s)
- E Manolakos
- Eurogenetica S.A., Laboratory of Genetics, Athens-Thessaloniki, Greece.
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Pascual FT, Wierenga KJ, Ng YT. Contiguous deletion of KCNQ2 and CHRNA4 may cause a different disorder from benign familial neonatal seizures. EPILEPSY & BEHAVIOR CASE REPORTS 2013; 1:35-8. [PMID: 25667822 PMCID: PMC4150641 DOI: 10.1016/j.ebcr.2013.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 01/31/2013] [Indexed: 11/19/2022]
Abstract
Benign familial neonatal seizures (BFNS) is an autosomal dominant disorder associated with heterozygous mutations of either the KCNQ2 or KCNQ3 gene. Most cases have mutations of the KCNQ2 gene. A handful of cases with KCNQ2 and CHRNA4 deletions have been identified with different phenotypic presentations. Only two cases presented with typical BFNS features. Benign familial neonatal seizures is associated with normal exam and work-up, and seizure remission is seen in the first month of life. We report three unrelated individuals with KCNQ2 and CHRNA4 deletions, presenting with neonatal seizures and developmental delay. Their seizures started within one week after birth; all required antiepileptic drugs. Each had normal brain magnetic resonance imaging and at least two electroencephalograms with either normal or abnormal findings. All were developmentally delayed. None presented with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) phenotype associated with CHRNA4 mutation. This study supports reports of KCNQ2 and CHRNA4 deletions associated with phenotypes different from typical BFNS.
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Affiliation(s)
- Franchette T. Pascual
- Department of Neurology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
- Corresponding author at: Department of Neurology, OUHSC, 711 Stanton L. Young Boulevard, Suite 210, Oklahoma City, OK 73104, USA. Tel.: + 1 405 271 4113.
| | - Klaas J. Wierenga
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Yu-Tze Ng
- Department of Neurology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Kim JW, Park JY, Oh AR, Choi EY, Ryu HM, Kang IS, Koong MK, Park SY. Duplication of intrachromosomal insertion segments 4q32→q35 confirmed by comparative genomic hybridization and fluorescent in situ hybridization. Clin Exp Reprod Med 2011; 38:238-41. [PMID: 22384449 PMCID: PMC3283076 DOI: 10.5653/cerm.2011.38.4.238] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 12/26/2011] [Accepted: 12/27/2011] [Indexed: 11/06/2022] Open
Abstract
A 35-year-old man with infertility was referred for chromosomal analysis. In routine cytogenetic analysis, the patient was seen to have additional material of unknown origin on the terminal region of the short arm of chromosome 4. To determine the origin of the unknown material, we carried out high-resolution banding, comparative genomic hybridization (CGH), and FISH. CGH showed a gain of signal on the region of 4q32→q35. FISH using whole chromosome painting and subtelomeric region probes for chromosome 4 confirmed the aberrant chromosome as an intrachromosomal insertion duplication of 4q32→q35. Duplication often leads to some phenotypic abnormalities; however, our patient showed an almost normal phenotype except for congenital dysfunction in spermatogenesis.
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Affiliation(s)
- Jin Woo Kim
- Laboratory of Medical Genetics, Cheil General Hospital and Women's Healthcare Center, Kwandong University College of Medicine, Seoul, Korea
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D'Angelo CS, de Oliveira MA, de Castro CIE, Koiffmann CP. Molecular cytogenetic characterization of an inherited maternal duplication 20p11.21p13 associated with a small 20p11.21 deletion. Am J Med Genet A 2011; 152A:3197-202. [PMID: 21108409 DOI: 10.1002/ajmg.a.33741] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Carla S D'Angelo
- Department of Genetics and Evolutionary Biology, Center for Human Genome Research, Institute of Biosciences, University of São Paulo, São Paulo, Brazil.
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Traylor RN, Bruno DL, Burgess T, Wildin R, Spencer A, Ganesamoorthy D, Amor DJ, Hunter M, Caplan M, Rosenfeld JA, Theisen A, Torchia BS, Shaffer LG, Ballif BC, Slater HR. A genotype-first approach for the molecular and clinical characterization of uncommon de novo microdeletion of 20q13.33. PLoS One 2010; 5:e12462. [PMID: 20805988 PMCID: PMC2929201 DOI: 10.1371/journal.pone.0012462] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 06/16/2010] [Indexed: 11/21/2022] Open
Abstract
Background Subtelomeric deletions of the long arm of chromosome 20 are rare, with only 11 described in the literature. Clinical features of individuals with these microdeletions include severe limb malformations, skeletal abnormalities, growth retardation, developmental and speech delay, mental retardation, seizures and mild, non-specific dysmorphic features. Methodology/Principal Findings We characterized microdeletions at 20q13.33 in six individuals referred for genetic evaluation of developmental delay, mental retardation, and/or congenital anomalies. A comparison to previously reported cases of 20q13.33 microdeletion shows phenotypic overlap, with clinical features that include mental retardation, developmental delay, speech and language deficits, seizures, and behavior problems such as autistic spectrum disorder. There does not appear to be a clinically recognizable constellation of dysmorphic features among individuals with subtelomeric 20q microdeletions. Conclusions/Significance Based on genotype-phenotype correlation among individuals in this and previous studies, we discuss several possible candidate genes for specific clinical features, including ARFGAP1, CHRNA4 and KCNQ2 and neurodevelopmental deficits. Deletion of this region may play an important role in cognitive development.
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Affiliation(s)
- Ryan N Traylor
- Signature Genomic Laboratories, Spokane, Washington, United States of America
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Wang JC, Dang L, Fisker T. Chromosome 6 between-arm intrachromosomal insertion with intrasegmental double inversion: a four-break model. Am J Med Genet A 2010; 152A:209-11. [PMID: 20034066 DOI: 10.1002/ajmg.a.33161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jia-Chi Wang
- Cytogenetics Laboratory, Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton, Ontario, Canada.
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Descipio C, Morrissette JD, Conlin LK, Clark D, Kaur M, Coplan J, Riethman H, Spinner NB, Krantz ID. Two siblings with alternate unbalanced recombinants derived from a large cryptic maternal pericentric inversion of chromosome 20. Am J Med Genet A 2010; 152A:373-82. [PMID: 20101690 DOI: 10.1002/ajmg.a.33219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Two brothers, with dissimilar clinical features, were each found to have different abnormalities of chromosome 20 by subtelomere fluorescence in situ hybridization (FISH). The proband had deletion of 20p subtelomere and duplication of 20q subtelomere, while his brother was found to have a duplication of 20p subtelomere and deletion of 20q subtelomere. Parental cytogenetic studies were initially thought to be normal, both by G-banding and by subtelomere FISH analysis. Since chromosome 20 is a metacentric chromosome and an inversion was suspected, we used anchored FISH to assist in identifying a possible inversion. This approach employed concomitant hybridization of a FISH probe to the short (p) arm of chromosome 20 with the 20q subtelomere probe. We identified a cytogenetically non-visible, mosaic pericentric inversion of one of the maternal chromosome 20 homologs, providing a mechanistic explanation for the chromosomal abnormalities present in these brothers. Array comparative genomic hybridization (CGH) with both a custom-made BAC and cosmid-based subtelomere specific array (TEL array) and a commercially available SNP-based array confirmed and further characterized these rearrangements, identifying this as the largest pericentric inversion of chromosome 20 described to date. TEL array data indicate that the 20p breakpoint is defined by BAC RP11-978M13, approximately 900 kb from the pter; SNP array data reveal this breakpoint to occur within BAC RP11-978M13. The 20q breakpoint is defined by BAC RP11-93B14, approximately 1.7 Mb from the qter, by TEL array; SNP array data refine this breakpoint to within a gap between BACs on the TEL array (i.e., between RP11-93B14 and proximal BAC RP11-765G16).
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Affiliation(s)
- Cheryl Descipio
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
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Lybaek H, Ørstavik KH, Prescott T, Hovland R, Breilid H, Stansberg C, Steen VM, Houge G. An 8.9 Mb 19p13 duplication associated with precocious puberty and a sporadic 3.9 Mb 2q23.3q24.1 deletion containing NR4A2 in mentally retarded members of a family with an intrachromosomal 19p-into-19q between-arm insertion. Eur J Hum Genet 2009; 17:904-10. [PMID: 19156171 DOI: 10.1038/ejhg.2008.261] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In a 2 and a half-year-old girl with onset of puberty before the age of 5 months, short stature, hand anomalies and severe mental retardation, an 8.9 Mb interstitial 19p13 duplication containing 215 predicted genes was detected. It was initially assumed that the duplication involved the kisspeptin receptor gene, GPR54, known to stimulate induction of puberty, but more refined duplication mapping excluded this possibility. In an attempt to further understand the genotype-phenotype correlation, global gene expression was measured in skin fibroblasts. The overall expression pattern was quite similar to controls, and only about 25% of the duplicated genes had an expression level that was increased by more than 1.3-fold, with no obvious changes that could explain the precocious puberty. The proband's mother carried a balanced between-arm insertion of the duplicated segment that resembled a pericentric inversion. The same insertion was found in several other family members, including one who had lost a daughter with severe mental retardation and menarche at the age of 10 years. Another close relative was severely mentally retarded, but neither dysmorphic nor microcephalic. His phenotype was initially ascribed to a presumed cryptic chromosome 19 imbalance caused by the 19p-into19q insertion, but subsequent array-CGH detected a 3.9-Mb deletion of 2q23.3q24.1. This novel microdeletion involves seven genes, of which FMNL2, a suggested regulator of Rho-GTPases, and NR4A2, an essential gene for differentiation of dopaminergic neurons, may be critical genes for the proposed 2q23q24 microdeletion syndrome.
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Affiliation(s)
- Helle Lybaek
- Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Helse Bergen HF, Norway.
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Basinko A, Douet-Guilbert N, Le Bris MJ, Parent P, Ansquer H, Morel F, De Braekeleer M. Molecular cytogenetic characterization of an 8p22-8p23.2 duplication derived from a maternal intrachromosomal insertion in a child with congenital heart malformation, delayed puberty, and learning disabilities. Am J Med Genet A 2008; 146A:2950-4. [DOI: 10.1002/ajmg.a.32522] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Béri-Deixheimer M, Gregoire MJ, Toutain A, Brochet K, Briault S, Schaff JL, Leheup B, Jonveaux P. Genotype–phenotype correlations to aid in the prognosis of individuals with uncommon 20q13.33 subtelomere deletions: a collaborative study on behalf of the ‘association des Cytogénéticiens de langue Française’. Eur J Hum Genet 2007; 15:446-52. [PMID: 17290276 DOI: 10.1038/sj.ejhg.5201784] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The identification of subtelomeric rearrangements as a cause of mental retardation has made a considerable contribution to diagnosing patients with mental retardation. It is remarkable that for certain subtelomeric regions, deletions have hardly ever been reported so far. All the laboratories from the 'Association des Cytogénéticiens de Langue Française' were surveyed for cases where an abnormality of the subtelomere FISH analysis had been ascertained. Among 1511 cases referred owing to unexplained mental retardation, 115 (7.6%) patients showed a clinically significant subtelomeric abnormality. We report the clinical features and the molecular cytogenetic delineation of isolated de novo deletions on 20q13.33 in two cases. Detailed mapping was performed by micro-array CGH in one patient and confirmed by FISH in the two patients. We compare our data with the only three patients reported in the literature. Both patients shared a deleted region of approximately 1.33 Mb including 40 genes, with a 324 kb difference between the two patients. Haploinsufficiency for CHRNA4 and ARFGAP1 may have contributed towards a severe phenotype. In addition, the data in all patients suggest that haploinsufficiency for SOX18 may not cause the hypotrichosis-lymphedema-telangiectasia syndrome, or causes milder disease. Our study gives important information by defining the size of imbalance and better predicting the phenotype. Two clinically distinct phenotypes may be drawn, a mild mental retardation or a more complex and severe phenotype, according to the presence or absence of the CHRNA4 and ARFGAP1 genes respectively.
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Béna F, Bottani A, Marcelli F, Sizonenko LD, Conrad B, Dahoun S. A de novo 1.1–1.6 Mb subtelomeric deletion of chromosome 20q13.33 in a patient with learning difficulties but without obvious dysmorphic features. Am J Med Genet A 2007; 143A:1894-9. [PMID: 17632785 DOI: 10.1002/ajmg.a.31789] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We report on a de novo submicroscopic deletion of 20q13.33 identified by subtelomeric fluorescence in situ hybridization (FISH) in a 4-year-old girl with learning difficulties, hyperlaxity and strabismus, but without obvious dysmorphic features. Further investigations by array-based comparative genomic hybridization (array-CGH) and FISH analysis allowed us to delineate the smallest reported subterminal deletion of chromosome 20q, spanning a 1.1-1.6 Mb with a breakpoint localized between BAC RP5-887L7 and RP11-261N11. The genes CHRNA4 and KCNQ2 implicated in autosomal dominant epilepsy are included in the deletion interval. Subterminal 20q deletions as found in the present patient have, to our knowledge, only been reported in three patients. We review the clinical and behavioral phenotype of such "pure" subterminal 20q deletions.
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Affiliation(s)
- Frédérique Béna
- Service of Medical Genetics, Department of Gynecology and Obstetrics, Geneva University Hospitals, Geneva, Switzerland.
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