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Corona-Rivera JR, Corona-Rivera A, Zepeda-Romero LC, Rios-Flores IM, Rivera-Vargas J, Orozco-Vela M, Santana-Bejarano UF, Torres-Anguiano E, Pinto-Cardoso M, David D, Bobadilla-Morales L. Ring chromosome 6 in a child with anterior segment dysgenesis and review of its overlap with other FOXC1 deletion phenotypes. Congenit Anom (Kyoto) 2019; 59:174-178. [PMID: 30225942 DOI: 10.1111/cga.12309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 09/11/2018] [Accepted: 09/12/2018] [Indexed: 12/25/2022]
Abstract
Here, we report a patient with ring chromosome 6 [r(6)], associated with anterior segment dysgenesis (ASD) and other anomalies. The phenotype was due to a 1880 kb microdeletion at 6p25.3 identified by whole-genome array analysis, and was mainly attributable to a FOXC1 haploinsufficiency. Currently 37 patients with r(6) have been reported. We found that facial dysmorphism, ASD, heart anomalies, brain anomalies, and hearing loss are constant features only in severe cases of r(6), mainly related to hemizygosity of FOXC1. Thus, overlaps with other FOXC1 related phenotypes, such as the 6p25 deletion syndrome, Axenfeld-Rieger syndrome type 3, and ASD type 3. Contrarily, those patients whose r(6) does not disrupt FOXC1, have mild or moderate phenotypes and do not exhibit ASD.
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Affiliation(s)
- Jorge Román Corona-Rivera
- Center for Registry and Research on Congenital Anomalies (CRIAC), Service of Genetics and Cytogenetics Unit, Division of Pediatrics, "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara, Guadalajara, Mexico.,'Dr. Enrique Corona-Rivera' Institute of Human Genetics, Department of Molecular Biology and Genomics, Health Sciences University Center, University of Guadalajara, Guadalajara, Mexico
| | - Alfredo Corona-Rivera
- Center for Registry and Research on Congenital Anomalies (CRIAC), Service of Genetics and Cytogenetics Unit, Division of Pediatrics, "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara, Guadalajara, Mexico.,'Dr. Enrique Corona-Rivera' Institute of Human Genetics, Department of Molecular Biology and Genomics, Health Sciences University Center, University of Guadalajara, Guadalajara, Mexico
| | - Luz Consuelo Zepeda-Romero
- Service of Ophthalmology, Division of Pediatrics, 'Fray Antonio Alcalde' Civil Hospital of Guadalajara, Guadalajara, Mexico
| | - Izabel Maryalexandra Rios-Flores
- Center for Registry and Research on Congenital Anomalies (CRIAC), Service of Genetics and Cytogenetics Unit, Division of Pediatrics, "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara, Guadalajara, Mexico
| | - Jehú Rivera-Vargas
- Center for Registry and Research on Congenital Anomalies (CRIAC), Service of Genetics and Cytogenetics Unit, Division of Pediatrics, "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara, Guadalajara, Mexico.,'Dr. Enrique Corona-Rivera' Institute of Human Genetics, Department of Molecular Biology and Genomics, Health Sciences University Center, University of Guadalajara, Guadalajara, Mexico
| | - Mireya Orozco-Vela
- 'Dr. Enrique Corona-Rivera' Institute of Human Genetics, Department of Molecular Biology and Genomics, Health Sciences University Center, University of Guadalajara, Guadalajara, Mexico
| | - Uriel Francisco Santana-Bejarano
- 'Dr. Enrique Corona-Rivera' Institute of Human Genetics, Department of Molecular Biology and Genomics, Health Sciences University Center, University of Guadalajara, Guadalajara, Mexico
| | - Elizabeth Torres-Anguiano
- 'Dr. Enrique Corona-Rivera' Institute of Human Genetics, Department of Molecular Biology and Genomics, Health Sciences University Center, University of Guadalajara, Guadalajara, Mexico
| | - Manuela Pinto-Cardoso
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Lisbon, Portugal
| | - Dezső David
- Department of Human Genetics, National Health Institute Doutor Ricardo Jorge, Lisbon, Portugal
| | - Lucina Bobadilla-Morales
- Center for Registry and Research on Congenital Anomalies (CRIAC), Service of Genetics and Cytogenetics Unit, Division of Pediatrics, "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara, Guadalajara, Mexico.,'Dr. Enrique Corona-Rivera' Institute of Human Genetics, Department of Molecular Biology and Genomics, Health Sciences University Center, University of Guadalajara, Guadalajara, Mexico
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2
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Sheth F, Liehr T, Shah V, Shah H, Tewari S, Solanki D, Trivedi S, Sheth J. A child with intellectual disability and dysmorphism due to complex ring chromosome 6: identification of molecular mechanism with review of literature. Ital J Pediatr 2018; 44:114. [PMID: 30305128 PMCID: PMC6180451 DOI: 10.1186/s13052-018-0571-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 09/21/2018] [Indexed: 11/29/2022] Open
Abstract
Background Ring chromosome 6 (r(6)) is a rare disorder that mainly occurs as a ‘de novo’ event. Nonetheless, a wide phenotypic spectrum has been reported in r(6) cases, depending on breakpoints, size of involved region, copy number alterations and mosaicism of cells with r(6) and/or monosomy 6 due to loss of r(6). Case presentation An 11-year-old male was referred with developmental delay, intellectual disability and microcephaly. Physical examination revealed additionally short stature and multiple facial dysmorphisms. Banding cytogenetic studies revealed a karyotype of mos 46,XY,r(6)(p25.3q27)[54]/45,XY,-6[13]/46,XY,r(6)(::p25.3→q27::p25.3→q27::)[13]/46,XY[6]/47,XY,r(6)(p25.3q27)×2[2]dn. Additionally, molecular karyotyping and molecular cytogenetics confirmed the breakpoints and characterized a 1.3 Mb contiguous duplication at 6p25.3. Conclusion The present study has accurately identified copy number alterations caused by ring chromosome formation. A review of the literature suggests that hemizygous expression of TBP gene in 6q27~qter, is likely to be the underlying cause of the phenotype. The phenotypic correlation and clinical severity in r(6) cases continue to remain widely diverse in spite of numerous reports of genomic variations.
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Affiliation(s)
- Frenny Sheth
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380009, India.
| | - Thomas Liehr
- University Clinic Jena, Institute of Human Genetics, Am Klinikum 1, 07747, Jena, Germany
| | - Viraj Shah
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380009, India
| | - Hillary Shah
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380009, India
| | - Stuti Tewari
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380009, India
| | - Dhaval Solanki
- Mantra Child Neurology & Epilepsy Hospital, 3rd floor, Oarnate complex, Kalubha road, Kalanala, Bhavanagar, 364001, India
| | - Sunil Trivedi
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380009, India
| | - Jayesh Sheth
- FRIGE's Institute of Human Genetics, FRIGE House, Jodhpur Gam Road, Satellite, Ahmedabad, 380009, India
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3
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Liu S, Wang Z, Wei S, Liang J, Chen N, OuYang H, Zeng W, Chen L, Xie X, Jiang J. Gray Matter Heterotopia, Mental Retardation, Developmental Delay, Microcephaly, and Facial Dysmorphisms in a Boy with Ring Chromosome 6: A 10-Year Follow-Up and Literature Review. Cytogenet Genome Res 2018; 154:201-208. [DOI: 10.1159/000488692] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Indexed: 11/19/2022] Open
Abstract
Ring chromosome 6, r(6), is an extremely rare cytogenetic abnormality with clinical heterogeneity which arises typically de novo. The phenotypes of r(6) can be highly variable, ranging from almost normal to severe malformations and neurological defects. Up to now, only 33 cases have been reported in the literature. In this 10-year follow-up study, we report a case presenting distinctive facial features, severe developmental delay, and gray matter heterotopia with r(6) and terminal deletions of 6p25.3 (115426-384174, 268 kb) and 6q26-27 (168697778-170732033, 2.03 Mb) encompassing 2 and 15 candidate genes, respectively, which were detected using G-banding karyotyping, FISH, and chromosomal microarray analysis. We also analyzed the available information on the clinical features of the reported r(6) cases in order to provide more valuable information on genotype-phenotype correlations. To the best of our knowledge, this is the first report of gray matter heterotopia manifested in a patient with r(6) in China, and the deletions of 6p and 6q in our case are the smallest with the precise size of euchromatic material loss currently known.
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Pace NP, Maggouta F, Twigden M, Borg I. Molecular cytogenetic characterisation of a novel de novo ring chromosome 6 involving a terminal 6p deletion and terminal 6q duplication in the different arms of the same chromosome. Mol Cytogenet 2017; 10:9. [PMID: 28344652 PMCID: PMC5364590 DOI: 10.1186/s13039-017-0311-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/17/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ring chromosome 6 is a rare sporadic chromosomal abnormality, associated with extreme variability in clinical phenotypes. Most ring chromosomes are known to have deletions on one or both chromosomal arms. Here, we report an atypical and unique ring chromosome 6 involving both a distal deletion and a distal duplication on the different arms of the same chromosome. CASE PRESENTATION In a patient with intellectual disability, short stature, microcephaly, facial dysmorphology, congenital heart defects and renovascular disease, a ring chromosome 6 was characterised using array-CGH and dual-colour FISH. The de-novo ring chromosome 6 involved a 1.8 Mb terminal deletion in the distal short arm and a 2.5 Mb duplication in the distal long arm of the same chromosome 6. This results in monosomy for the region 6pter to 6p25.3 and trisomy for the region 6q27 to 6qter. Analysis of genes in these chromosomal regions suggests that haploinsufficiency for FOXC1 and GMDS genes accounts for the cardiac and neurodevelopmental phenotypes in the proband. The ring chromosome 6 reported here is atypical as it involves a unique duplication of the distal long arm. Furthermore, the presence of renovascular disease is also a unique feature identified in this patient. CONCLUSION To the best of our knowledge, a comparable ring chromosome 6 involving both a distal deletion and duplication on different arms has not been previously reported. The renovascular disease identified in this patient may be a direct consequence of the described chromosome rearrangement or a late clinical presentation in r(6) cases. This clinical finding may further support the implicated role of FOXC1 gene in renal pathology.
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Affiliation(s)
- Nikolai Paul Pace
- Centre for Molecular Medicine and Biobanking, Faculty of Medicine and Surgery, University of Malta, Msida, Malta
| | - Frideriki Maggouta
- Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Melissa Twigden
- Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Isabella Borg
- Centre for Molecular Medicine and Biobanking, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Department of Pathology, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Department of Pathology, Medical Genetics Unit, Mater Dei Hospital, Msida, Malta
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5
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Yang R, Li Y, Su Y, Shen Y, Tang D, Luo Q, Cheng Z. A functional centromere lacking CentO sequences in a newly formed ring chromosome in rice. J Genet Genomics 2016; 43:694-701. [PMID: 27965027 DOI: 10.1016/j.jgg.2016.09.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 09/10/2016] [Accepted: 09/22/2016] [Indexed: 11/29/2022]
Abstract
An awned rice (Oryza sativa) plant carrying a tiny extra chromosome was discovered among the progeny of a telotrisomic line 2n+4L. Fluorescence in situ hybridization (FISH) using chromosome specific BAC clones revealed that this extra chromosome was a ring chromosome derived from part of the long arm of chromosome 4. So the aneuploidy plant was accordingly named as 2n+4L ring. We did not detect any CentO FISH signals on the ring chromosome, and found only the centromeric probe Centromeric Retrotransposon of Rice (CRR) was co-localized with the centromere-specific histone CENH3 as revealed by sequential FISH after immunodetection. The extra ring chromosome exhibited a unique segregation pattern during meiosis, including no pairing between the ring chromosome and normal chromosome 4 during prophase I and pre-separation of sister chromatids at anaphase I.
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Affiliation(s)
- Rui Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Ministry of Education Key Laboratory of Agriculture Biodiversity for Plant Disease Management, Yunnan Agricultural University, Kunming 650201, China
| | - Yafei Li
- State Key Laboratory of Plant Genomics, Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yan Su
- State Key Laboratory of Plant Genomics, Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yi Shen
- State Key Laboratory of Plant Genomics, Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ding Tang
- State Key Laboratory of Plant Genomics, Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qiong Luo
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Ministry of Education Key Laboratory of Agriculture Biodiversity for Plant Disease Management, Yunnan Agricultural University, Kunming 650201, China.
| | - Zhukuan Cheng
- State Key Laboratory of Plant Genomics, Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
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6
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Nishigaki S, Hamazaki T, Saito M, Yamamoto T, Seto T, Shintaku H. Periventricular heterotopia and white matter abnormalities in a girl with mosaic ring chromosome 6. Mol Cytogenet 2015. [PMID: 26213576 PMCID: PMC4514952 DOI: 10.1186/s13039-015-0162-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Ring chromosome 6 is a rare chromosome abnormality that arises typically de novo. The phenotypes can be highly variable, ranging from almost normal to severe malformations and neurological defects. We report a case of a 3-year-old girl with mosaic ring chromosome 6 who presented with being small for gestational age and intellectual disability, and whose brain MRI later revealed periventricular heterotopia and white matter abnormalities. Mosaicism was identified in peripheral blood cells examined by standard G-bands, mos 46,XX,r(6)(p25q27)[67]/45,XX,-6[25]/46,XX,dic r(6:6)(p25q27:p25q27)[6]/47,XX,r(6)(p25q27) × 2[2]. Using array-comparative genomic hybridization, we identified terminal deletion of 6q27 (1.5 Mb) and no deletion on 6p. To our knowledge, this is the first report of periventricular heterotopia and white matter abnormalities manifested in a patient with ring chromosome 6. These central nervous system malformations are further discussed in relation to molecular genetics.
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Affiliation(s)
- Satsuki Nishigaki
- Department of Pediatrics, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585 Japan
| | - Takashi Hamazaki
- Department of Pediatrics, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585 Japan
| | - Mika Saito
- Department of Pediatrics, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585 Japan
| | - Toshiyuki Yamamoto
- Institute for Integrated Medical Sciences, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ward, Tokyo, 162-8666 Japan
| | - Toshiyuki Seto
- Department of Pediatrics, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585 Japan
| | - Haruo Shintaku
- Department of Pediatrics, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585 Japan
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7
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Abstract
Ring chromosomes arise following breakage and rejoining in both chromosome arms. They are heterogeneous with variable size and genetic content and can originate from any chromosome. Phenotypes associated with ring chromosomes are highly variable as apart from any deletion caused by ring formation, imbalances from ring instability can also occur. Of interest is ring chromosome 20 which has a significant association with epilepsy with seizure onset in early childhood. Severe growth deficiency without major malformations is a common finding in the ring chromosome carrier. This phenotype associated with ring behaviour and mitotic instability and independent of the chromosome involved has been termed the "ring syndrome". Precise genotype-phenotype correlations for ring chromosomes may not be possible as influencing factors vary depending on the extent of deletion in ring formation, ring instability and the level of mosaicism. Although ring chromosomes usually arise as de novo events, familial transmission of rings from carrier to offspring has been described and prenatal diagnosis for any pregnancies should always be considered.
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Affiliation(s)
- Moh-Ying Yip
- SEALS Genetics Laboratory, NSW Health Pathology, Prince of Wales Hospital, Randwick, Sydney, NSW 2031, Australia
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8
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Ciocca L, Surace C, Digilio MC, Roberti MC, Sirleto P, Lombardo A, Russo S, Brizi V, Grotta S, Cini C, Angioni A. Array-CGH characterization and genotype-phenotype analysis in a patient with a ring chromosome 6. BMC Med Genomics 2013; 6:3. [PMID: 23398904 PMCID: PMC3599180 DOI: 10.1186/1755-8794-6-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 01/28/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ring chromosome 6 is a rare constitutional abnormality that generally occurs de novo. The related phenotype may be highly variable ranging from an almost normal phenotype to severe malformations and mental retardation. These features are mainly present when genetic material at the end of the chromosome is lost. The severity of the phenotype seems to be related to the size of the deletion. About 25 cases have been described to date, but the vast majority reports only conventional cytogenetic investigations. CASE PRESENTATION Here we present an accurate cyto-molecular characterization of a ring chromosome 6 in a 16-months-old Caucasian girl with mild motor developmental delay, cardiac defect, and facial anomalies. The cytogenetic investigations showed a karyotype 46,XX,r(6)(p25q27) and FISH analysis revealed the absence of the signals on both arms of the chromosome 6. These results were confirmed by means of array-CGH showing terminal deletions on 6p25.3 (1.3 Mb) and 6q26.27 (6.7 Mb). Our data were compared to current literature. CONCLUSIONS Our report describes the case of a patient with a ring chromosome 6 abnormality completely characterized by array CGH which provided additional information for genotype-phenotype studies.
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Affiliation(s)
- Laura Ciocca
- Cytogenetics and Molecular Genetics Unit, Children's Hospital Bambino Gesù, IRCCS, Rome, Italy
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9
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Caba L, Rusu C, Plăiaşu, Gug G, Grămescu M, Bujoran C, Ochiană D, Voloşciuc M, Popescu R, Braha E, Pânzaru M, Butnariu L, Sireteanu A, Covic M, Gorduza EV. Ring autosomes: some unexpected findings. Balkan J Med Genet 2012; 15:35-46. [PMID: 24052730 PMCID: PMC3776666 DOI: 10.2478/bjmg-2013-0005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ring chromosomes are rare entities, usually associated with phenotypic abnormalities in correlation with the loss of genetic material. There are various breakpoints and sometimes there is a dynamic mosaicism that is reflected in clinical features. Most of the ring chromosomes are de novo occurrences. Our study reflects the experience of three Romanian cytogenetic laboratories in the field of ring chromosomes. We present six cases with ring chromosomes involving chromosomes 5, 13, 18, and 21. All ring chromosomes were identified after birth in children with plurimalformative syndromes. The ring chromosome was present in mosaic form in three cases, and this feature reflects the ring's instability. In case of ring chromosome 5, we report a possible association with oculo-auriculo-vertebral spectrum.
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Affiliation(s)
- L Caba
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
| | - C Rusu
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
- “Sf. Maria” Pediatric Hospital Iasi, Department of Medical Genetics, Iasi, Romania
| | - Plăiaşu
- “Prof. dr. Alfred Rusescu” Institute for Mother and Child Care Bucharest, Department of Medical Genetics, Bucharest, Romania
| | - G Gug
- “Victor Babeş” University of Medicine and Pharmacy Timisoara, Department of Medical Genetics, Timisoara, Romania
- “Dr. Cristina Gug” Cytogenetic Laboratory, Timisoara, Romania
| | - M Grămescu
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
| | - C Bujoran
- “Sf. Maria” Pediatric Hospital Iasi, Department of Medical Genetics, Iasi, Romania
| | - D Ochiană
- “Prof. dr. Alfred Rusescu” Institute for Mother and Child Care Bucharest, Department of Medical Genetics, Bucharest, Romania
| | - M Voloşciuc
- “Sf. Maria” Pediatric Hospital Iasi, Department of Medical Genetics, Iasi, Romania
| | - R Popescu
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
| | - E Braha
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
- “Sf. Maria” Pediatric Hospital Iasi, Department of Medical Genetics, Iasi, Romania
| | - M Pânzaru
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
- “Sf. Maria” Pediatric Hospital Iasi, Department of Medical Genetics, Iasi, Romania
| | - L Butnariu
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
- “Sf. Maria” Pediatric Hospital Iasi, Department of Medical Genetics, Iasi, Romania
| | - A Sireteanu
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
| | - M Covic
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
| | - EV Gorduza
- “Grigore T. Popa” University of Medicine and Pharmacy Iasi, Department of Medical Genetics, Iasi, Romania
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Abstract
Somatic mosaicism is the result of postzygotic de novo mutation occurring in a portion of the cells making up an organism. Structural genetic variation is a very heterogeneous group of changes, in terms of numerous types of aberrations that are included in this category, involvement of many mechanisms behind the generation of structural variants, and because structural variation can encompass genomic regions highly variable in size. Structural variation rapidly evolved as the dominating type of changes behind human genetic diversity, and the importance of this variation in biology and medicine is continuously increasing. In this review, we combine the evidence of structural variation in the context of somatic cells. We discuss the normal and disease-related somatic structural variation. We review the recent advances in the field of monozygotic twins and other models that have been studied for somatic mutations, including other vertebrates. We also discuss chromosomal mosaicism in a few prime examples of disease genes that contributed to understanding of the importance of somatic heterogeneity. We further highlight challenges and opportunities related to this field, including methodological and practical aspects of detection of somatic mosaicism. The literature devoted to interindividual variation versus papers reporting on somatic variation suggests that the latter is understudied and underestimated. It is important to increase our awareness about somatic mosaicism, in particular, related to structural variation. We believe that further research of somatic mosaicism will prove beneficial for better understanding of common sporadic disorders.
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11
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Guilherme RS, Meloni VFA, Kim CA, Pellegrino R, Takeno SS, Spinner NB, Conlin LK, Christofolini DM, Kulikowski LD, Melaragno MI. Mechanisms of ring chromosome formation, ring instability and clinical consequences. BMC MEDICAL GENETICS 2011; 12:171. [PMID: 22188645 PMCID: PMC3309960 DOI: 10.1186/1471-2350-12-171] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 12/21/2011] [Indexed: 11/15/2022]
Abstract
Background The breakpoints and mechanisms of ring chromosome formation were studied and mapped in 14 patients. Methods Several techniques were performed such as genome-wide array, MLPA (Multiplex Ligation-Dependent Probe Amplification) and FISH (Fluorescent in situ Hybridization). Results The ring chromosomes of patients I to XIV were determined to be, respectively: r(3)(p26.1q29), r(4)(p16.3q35.2), r(10)(p15.3q26.2), r(10)(p15.3q26.13), r(13)(p13q31.1), r(13)(p13q34), r(14)(p13q32.33), r(15)(p13q26.2), r(18)(p11.32q22.2), r(18)(p11.32q21.33), r(18)(p11.21q23), r(22)(p13q13.33), r(22)(p13q13.2), and r(22)(p13q13.2). These rings were found to have been formed by different mechanisms, such as: breaks in both chromosome arms followed by end-to-end reunion (patients IV, VIII, IX, XI, XIII and XIV); a break in one chromosome arm followed by fusion with the subtelomeric region of the other (patients I and II); a break in one chromosome arm followed by fusion with the opposite telomeric region (patients III and X); fusion of two subtelomeric regions (patient VII); and telomere-telomere fusion (patient XII). Thus, the r(14) and one r(22) can be considered complete rings, since there was no loss of relevant genetic material. Two patients (V and VI) with r(13) showed duplication along with terminal deletion of 13q, one of them proved to be inverted, a mechanism known as inv-dup-del. Ring instability was detected by ring loss and secondary aberrations in all but three patients, who presented stable ring chromosomes (II, XIII and XIV). Conclusions We concluded that the clinical phenotype of patients with ring chromosomes may be related with different factors, including gene haploinsufficiency, gene duplications and ring instability. Epigenetic factors due to the circular architecture of ring chromosomes must also be considered, since even complete ring chromosomes can result in phenotypic alterations, as observed in our patients with complete r(14) and r(22).
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Affiliation(s)
- Roberta S Guilherme
- Genetics Division, Department of Morphology and Genetics, Federal University of São Paulo, Botucatu Street 740, Zip Code 04023-900, São Paulo, Brazil.
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12
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Sodré CP, Guilherme RS, Meloni VFA, Brunoni D, Juliano Y, Andrade JAD, Belangero SIN, Christofolini DM, Kulikowski LD, Melaragno MI. Ring chromosome instability evaluation in six patients with autosomal rings. GENETICS AND MOLECULAR RESEARCH 2010; 9:134-43. [PMID: 20198569 DOI: 10.4238/vol9-1gmr707] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ring chromosomes are often associated with abnormal phenotypes due to loss of genomic material and also because of ring instability at mitosis after sister chromatid exchange events. We investigated ring chromosome instability in six patients with ring chromosomes 4, 14, 15, and 18 by examining 48- and 72-h lymphocyte cultures at the first, second and subsequent cell divisions after bromodeoxyuridine incorporation. Although most cells from all patients showed only one monocentric ring chromosome, ring chromosome loss and secondary aberrations were observed both in 48- and 72-h lymphocyte cultures and in metaphase cells of the different cell generations. We found no clear-cut correlation between ring size and ring instability; we also did not find differences between apparently complete rings and rings with genetic material loss. The cytogenetic findings revealed secondary aberrations in all ring chromosome patients. We concluded that cells with ring chromosome instability can multiply and survive in vivo, and that they can influence the patient's phenotype.
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Affiliation(s)
- C P Sodré
- Departamento de Morfologia e Genética da Universidade Federal de São Paulo, São Paulo, SP, Brasil
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