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Xie Y, Xu XL, Wei WB. The RB1 Mutation Spectrum and Genetic Management Consultation in Pediatric Patients with Retinoblastoma in Beijing, China. Risk Manag Healthc Policy 2021; 14:3453-3463. [PMID: 34456592 PMCID: PMC8387327 DOI: 10.2147/rmhp.s322373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/22/2021] [Indexed: 11/23/2022] Open
Abstract
Objective The present study screened the structural mutations of the retinoblastoma (RB1) gene using gene capture and a preliminary exploration of the correlation between the genotypes and phenotypes. Methods A total of 45 formalin-fixed paraffin-embedded (FFPE) tissue samples and 12 peripheral venous blood samples from patients with retinoblastoma (RB) confirmed by pathological examination at Beijing Tongren Hospital were collected between May 2019 and May 2021. DNA from the samples was extracted, sequenced, and analyzed to detect the mutations in the RB1 gene by designing the targeted capture probes for exons and the flanking sequences of the gene. Results Of the 45 FFPE tissue samples, 23 were from male patients and 22 were from female patients, all aged between 4 months and 10 years, with an average age of 2.5 ± 1.3 years. Two of these patients had bilateral RB and 43 had unilateral RB (23 in the right eye and 20 in the left eye). Of the 12 peripheral venous blood samples, 7 were from male patients and 5 were from female patients, all aged between 8 months and 4 years, with an average age of 1.3 ± 0.9 years. Two of these patients had bilateral RB and 10 had unilateral RB (8 in the right eye and 2 in the left eye). Three de novo pathogenic mutations were found in the FFPE tissues, along with one de novo potentially pathogenic mutation, while three de novo potentially pathogenic mutations were found in the blood samples. Conclusion Gene capture is a low-cost and efficient method for the gene sequencing of RB. A total of seven de novo mutations were identified through mutation testing of the pathogenic gene RB1 in 56 pediatric patients with RB. This complemented the mutation spectrum of the RB1 gene and helped to improve the molecular diagnosis of RB, thereby providing a basis for genetic counseling and prediction of the clinical phenotype, as well as for the genetic testing of the offspring of patients with RB. Clinical Registration Number ChiCTR-EPC-17013892.
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Affiliation(s)
- Ying Xie
- Beijing Tongren Eye Center, Beijing Key Laboratory of Intraocular Tumor Diagnosis and Treatment, Beijing Ophthalmology and Visual Sciences Key Lab, Medical Artificial Intelligence Research and Verification Key Laboratory of the Ministry of Industry and Information Technology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, People's Republic of China.,Department of Opthalmology, Shanxi Provincial People's Hospital, Taiyuan, 030012, People's Republic of China
| | - Xiao-Lin Xu
- Beijing Tongren Eye Center, Beijing Key Laboratory of Intraocular Tumor Diagnosis and Treatment, Beijing Ophthalmology and Visual Sciences Key Lab, Medical Artificial Intelligence Research and Verification Key Laboratory of the Ministry of Industry and Information Technology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, People's Republic of China
| | - Wen-Bin Wei
- Beijing Tongren Eye Center, Beijing Key Laboratory of Intraocular Tumor Diagnosis and Treatment, Beijing Ophthalmology and Visual Sciences Key Lab, Medical Artificial Intelligence Research and Verification Key Laboratory of the Ministry of Industry and Information Technology, Beijing Tongren Hospital, Capital Medical University, Beijing, 100730, People's Republic of China
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2
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Thirumalairaj K, Abraham A, Devarajan B, Gaikwad N, Kim U, Muthukkaruppan V, Vanniarajan A. A stepwise strategy for rapid and cost-effective RB1 screening in Indian retinoblastoma patients. J Hum Genet 2015; 60:547-52. [PMID: 26084579 DOI: 10.1038/jhg.2015.62] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 01/02/2023]
Abstract
India has the highest number of retinoblastoma (RB) patients among the developing countries owing to its increasing population. Of the patients with RB, about 40% have the heritable form of the disease, making genetic analysis of the RB1 gene an integral part of disease management. However, given the large size of the RB1 gene with its widely dispersed exons and no reported hotspots, genetic testing can be cumbersome. To overcome this problem, we have developed a rapid screening strategy by prioritizing the order of exons to be analyzed, based on the frequency of nonsense mutations, deletions and duplications reported in the RB1-Leiden Open Variation Database and published literature on Indian patients. Using this strategy for genetic analysis, mutations were identified in 76% of patients in half the actual time and one third of the cost. This reduction in time and cost will allow for better risk prediction for siblings and offspring, thereby facilitating genetic counseling for families, especially in developing countries.
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Affiliation(s)
- Kannan Thirumalairaj
- Department of Molecular Genetics, Aravind Medical Research Foundation, Madurai, India
| | - Aloysius Abraham
- Department of Molecular Genetics, Aravind Medical Research Foundation, Madurai, India
| | | | - Namrata Gaikwad
- Department of Orbit, Oculoplasty and Oncology, Aravind Eye Hospital, Madurai, India
| | - Usha Kim
- Department of Orbit, Oculoplasty and Oncology, Aravind Eye Hospital, Madurai, India
| | | | - Ayyasamy Vanniarajan
- Department of Molecular Genetics, Aravind Medical Research Foundation, Madurai, India
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Hodgkinson CL, Morrow CJ, Li Y, Metcalf RL, Rothwell DG, Trapani F, Polanski R, Burt DJ, Simpson KL, Morris K, Pepper SD, Nonaka D, Greystoke A, Kelly P, Bola B, Krebs MG, Antonello J, Ayub M, Faulkner S, Priest L, Carter L, Tate C, Miller CJ, Blackhall F, Brady G, Dive C. Tumorigenicity and genetic profiling of circulating tumor cells in small-cell lung cancer. Nat Med 2014; 20:897-903. [PMID: 24880617 DOI: 10.1038/nm.3600] [Citation(s) in RCA: 530] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 05/16/2014] [Indexed: 12/11/2022]
Abstract
Small-cell lung cancer (SCLC), an aggressive neuroendocrine tumor with early dissemination and dismal prognosis, accounts for 15-20% of lung cancer cases and ∼200,000 deaths each year. Most cases are inoperable, and biopsies to investigate SCLC biology are rarely obtainable. Circulating tumor cells (CTCs), which are prevalent in SCLC, present a readily accessible 'liquid biopsy'. Here we show that CTCs from patients with either chemosensitive or chemorefractory SCLC are tumorigenic in immune-compromised mice, and the resultant CTC-derived explants (CDXs) mirror the donor patient's response to platinum and etoposide chemotherapy. Genomic analysis of isolated CTCs revealed considerable similarity to the corresponding CDX. Most marked differences were observed between CDXs from patients with different clinical outcomes. These data demonstrate that CTC molecular analysis via serial blood sampling could facilitate delivery of personalized medicine for SCLC. CDXs are readily passaged, and these unique mouse models provide tractable systems for therapy testing and understanding drug resistance mechanisms.
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Affiliation(s)
- Cassandra L Hodgkinson
- 1] Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK. [2]
| | - Christopher J Morrow
- 1] Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK. [2]
| | - Yaoyong Li
- Computational Biology Support Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Robert L Metcalf
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Dominic G Rothwell
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Francesca Trapani
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Radoslaw Polanski
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Deborah J Burt
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Kathryn L Simpson
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Karen Morris
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Stuart D Pepper
- Molecular Biology Core Facility, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | | | - Alastair Greystoke
- 1] Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK. [2] The Christie NHS Foundation Trust, Manchester, UK. [3] Institute of Cancer Sciences, University of Manchester, Manchester, UK
| | - Paul Kelly
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Becky Bola
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Matthew G Krebs
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Jenny Antonello
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Mahmood Ayub
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Suzanne Faulkner
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Lynsey Priest
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Louise Carter
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Catriona Tate
- Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Crispin J Miller
- 1] Computational Biology Support Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK. [2] RNA Biology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK
| | - Fiona Blackhall
- 1] The Christie NHS Foundation Trust, Manchester, UK. [2] Institute of Cancer Sciences, University of Manchester, Manchester, UK. [3]
| | - Ged Brady
- 1] Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK. [2]
| | - Caroline Dive
- 1] Clinical and Experimental Pharmacology Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester, UK. [2]
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Ahani A, Akbari MT, Saliminejad K, Behnam B, Akhondi MM, Vosoogh P, Ghassemi F, Naseripour M, Bahoush G, Khorshid HRK. Screening for large rearrangements of the RB1 gene in Iranian patients with retinoblastoma using multiplex ligation-dependent probe amplification. Mol Vis 2013; 19:454-62. [PMID: 23441118 PMCID: PMC3580967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 02/20/2013] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To screen deletions/duplications of the RB1 gene in a large cohort of Iranian patients using the multiplex ligation-dependent probe amplification (MLPA) technique. METHODS A total of 121 patients with retinoblastoma, involving 55 unilateral and 66 bilateral or familial retinoblastomas, were included in this study. Among these patients, 121 blood and 43 tissue samples were available. DNA was extracted from the blood and tissue samples and analyzed with an RB1-specific MLPA probe set. The mutation findings were validated with SYBR Green Real-Time PCR. RESULTS Twenty-two mutations were found in 21 patients; of these, ten mutations were detected in patients with isolated unilateral retinoblastoma. CONCLUSIONS Our results suggested that MLPA is a fast, reliable, and powerful method for detecting deletions/duplications in patients with retinoblastoma.
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Affiliation(s)
- Ali Ahani
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran,Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Taghi Akbari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Kioomars Saliminejad
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
| | - Babak Behnam
- Department of Genetics and Molecular Biology, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Mehdi Akhondi
- Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
| | | | - Farriba Ghassemi
- Eye Research Center, Farabi Hospital, Tehran University of Medical Sciences
| | - Masood Naseripour
- Eye Research Center, Rasoul Akram Hospital, Tehran University of Medical Sciences
| | - Gholamreza Bahoush
- Oncopathology Research Center, Ali-Asghar Children Hospital, Tehran University of Medical Sciences
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Ottaviani D, Parma D, Giliberto F, Ferrer M, Fandino A, Davila MT, Chantada G, Szijan I. Spectrum of RB1 mutations in argentine patients: 20-years experience in the molecular diagnosis of retinoblastoma. Ophthalmic Genet 2013; 34:189-98. [PMID: 23301675 DOI: 10.3109/13816810.2012.755553] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Retinoblastoma is a hereditary cancer of childhood caused by mutations in the RB1 tumor suppressor gene. An early diagnosis is critical for survival and eye preservation, thus identification of RB1 mutations is important for unequivocal diagnosis of hereditary retinoblastoma and risk assessment in relatives. METHODS We studied 144 families for 20 years, performing methodological changes to improve detection of mutation. Segregation analysis of polymorphisms, MLPA, FISH and cytogenetic assays were used for detection of "at risk haplotypes" and large deletions. Small mutations were identified by heteroduplex/DNA sequencing. RESULTS At risk haplotypes were identified in 11 familial and 26 sporadic cases, being useful for detection of asymptomatic carriers, risk exclusion from relatives and uncovering RB1 recombinations. Ten large deletions (eight whole gene deletions) were identified in six bilateral/familial and four unilateral retinoblastoma cases. Small mutations were identified in 29 cases (four unilateral retinoblastoma patients), being the majority nonsense/frameshift mutations. Genotype-phenotype correlations confirm that the retinoblastoma presentation is related to the type of mutation, but some exceptions may occur and it is crucial to be considered for genetic counseling. Three families included second cousins with retinoblastoma carrying different haplotypes, which suggest independent mutation events. CONCLUSION This study enabled us to obtain information about molecular and genetic features of patients with retinoblastoma in Argentina and correlate them to their phenotype.
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Affiliation(s)
- Daniela Ottaviani
- Genetica y Biologia Molecular, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires , Argentina
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Fernández C, Repetto K, Dalamon V, Bergonzi F, Ferreiro V, Szijan I. RB1 Germ-Line Deletions in Argentine Retinoblastoma Patients. Mol Diagn Ther 2012; 11:55-61. [PMID: 17286450 DOI: 10.1007/bf03256222] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Retinoblastoma (RB) is a malignant tumor originating in the retinal cell precursors and can be presented as a unilateral or bilateral form in childhood (one or both eyes affected). Development of this tumor is caused by mutations in the RB1 gene on chromosome 13q14; the first mutation may occur in the germ line (hereditary RB) or in somatic cells (non-hereditary RB). The hereditary form of RB is transmitted with a high penetrance to offspring (90%). Because early diagnosis is necessary for implementing effective treatment and preserving vision, it is important to identify the mutations in the affected family. AIM The aim of this study was to identify large and small RB1 germ-line mutations and to correlate them with the RB phenotype. METHODS Constitutional RB1 gene gross deletions were studied in 40 patients with bilateral or unilateral familial RB by a segregation assay of four intragenic polymorphisms located in introns 1, 4, 17, and 20 of the RB1 gene, along with fluorescence in situ hibridization (FISH) analysis. Small mutations were ascertained in a subgroup of ten patients by heteroduplex/sequence analysis of RB1-exons. RESULTS In the course of our study, we have found three large deletions, which probably represent whole gene deletions, and two small deletions of 1bp in length. One large deletion was found in a family with several members affected. This represents a rare case of familial RB, which is usually caused by small mutations. Phenotype analysis of the family revealed a low penetrance inheritance, with an 'affected eyes : number of mutation-carriers' ratio of approximately 1.0, whereas this ratio in families with small loss-of-function mutations is 1.5-2.0. CONCLUSIONS Our results emphasize the usefulness of a combined methodology that includes segregation of polymorphisms, FISH, and heteroduplex/sequence analyses for detection of gross and small DNA rearrangements in familial and sporadic RB. Identification of mutations in sporadic cases is important for risk-assessment in patients' relatives. The degree of penetrance in the inheritance of RB not only depends on the occurrence of the second mutation in the RB1 gene but also on the extent of inactivation of the first mutation.
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Affiliation(s)
- Cecilia Fernández
- Genetics and Molecular Biology Department, Faculty of Pharmacy, Jose de San Martin Hospital, Buenos Aires University, Buenos Aires, Argentina
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7
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Zahery SM, Saliminejad K, Khorshid HRK, Ahani A. Genotyping of Polymorphic Microsatellite Markers Linked to RB1 Locus in Iranian Population. Avicenna J Med Biotechnol 2012; 4:193-9. [PMID: 23407622 PMCID: PMC3558219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 07/03/2012] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Retinoblastoma is the most common intraocular tumor in childhood and mutation in the RB1 gene will trigger the tumorigenesis. So far, a wide range of the mutations along the length of RB1 gene have been reported. However, some could not be detected by common detection methods. In such condition, linkage analysis using microsatellite markers is suggested to trace unknown RB1 mutations in the affected family. The aim of the present study was to evaluate the heterozygosity rates and genotyping of three microsatellite markers near or inside of the RB1 gene. METHODS Totally, 120 unrelated healthy people from Fardis, Karaj, Iran were recruited and from each participant genomic DNA was extracted from 5 ml of peripheral blood. Three microsatellite markers D13S153, D13S156 and D13S128 located within or adjacent to the RB1 gene were selected for linkage analysis. The reliability of microsatellite markers and linkage analysis were investigated in 10 members of 2 families with familial retinoblastoma. RESULTS Our results showed that heterozygosity rates for the three markers D13S153, D13S156 and D13S128 were 74, 70 and 78%, respectively. On the other hand, 2 and 36 out of 120 people were homozygote and heterozygous for all loci, respectively. CONCLUSION Given the heterozygosity rates, it may be concluded that all microsatellite markers D13S153, D13S156 and D13S128 are informative and have a high rate of heterozygosity and sensitivity. Therefore, tracing the unknown RB1 mutated alleles using linkage analysis in Iranian family with familial retinoblastoma could be recommended by means of these three microsatellite markers.
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Affiliation(s)
- Saman Mohamad Zahery
- Reproductive Biotechnology Research Center, Avicenna Research Institute, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran,Monoclonal Antibody Research Center, Avicenna Research Institute, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran,These authors equally contributed to this work
| | - Kioomars Saliminejad
- Reproductive Biotechnology Research Center, Avicenna Research Institute, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran,These authors equally contributed to this work
| | | | - Ali Ahani
- Reproductive Biotechnology Research Center, Avicenna Research Institute, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran,Corresponding author: Ali Ahani, Ph.D., Reproductive Biotechnology Research Center, Avicenna Research Institute, Academic Center for Education, Culture and Research (ACECR), Tehran, Iran. Tel: +98 21 22432020. Fax: +98 21 22432021. E-mail:
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RB1 gene mutations in Iranian patients with retinoblastoma: report of four novel mutations. Cancer Genet 2011; 204:316-22. [PMID: 21763628 DOI: 10.1016/j.cancergen.2011.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 04/18/2011] [Accepted: 04/25/2011] [Indexed: 11/23/2022]
Abstract
Mutations in the RB1 gene lead to retinoblastoma, which is the most common intraocular tumor in children under the age of 6. In the present survey, the mutations of 18 unrelated Iranian retinoblastoma patients were characterized. Mutation analysis of the RB1 gene was performed in patients by sequencing all coding regions and by multiplex ligation probe-dependent amplification analysis. Clinical signs and symptoms of the retinoblastoma patients were similar to those of previously described patients with retinoblastoma. Eight known mutations and four novel mutations (c.832_833insT, c.1943delC, c.1206C>T, and c.2029delG) were determined. In silico analysis of the c.1206C>T variant showed that exon 12 contained an SC-35 consensus sequence, and this variation disrupted the splicing enhancer element and caused skipping of exon 12. Molecular genetic testing of retinoblastoma patients greatly affects the genetic counseling of the families involved, as well as the management of the disease in patients and at-risk relatives.
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Bamne MN, Ghule PN, Jose J, Banavali SD, Kurkure PA, Amare Kadam PS. Constitutional and somatic RB1 mutation spectrum in nonfamilial unilateral and bilateral retinoblastoma in India. ACTA ACUST UNITED AC 2006; 9:200-11. [PMID: 16225399 DOI: 10.1089/gte.2005.9.200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
An epidemiologic survey has indicated a comparatively high prevalence of retinoblastoma (Rb) in Asian countries. Recently, the development of preventive strategies in nonfamilial Rb has become a major goal. The present studies were designed for identification and characterization of constitutional and somatic RB1 gene mutations by conventional cytogenetics, fluorescent in situ hybridization (FISH) and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP)-DNA sequencing. Of 34 patients 32 were nonfamilial and 2 were familial Rb. Maternal inheritance of del (13q14) was common. FISH was sensitive in detecting monoallelic RB1 deletion/deletion mosaicism as a first genetic hit in 20% of cases. Somatic and germline RB1 point mutations affected exons 3, 17, 20, and 21 and these were identified as novel mutations. Involvement of exon 20 as a predisposing mutation in sporadic unilateral retinoblastoma (URB) probably suggests the susceptibility of exon 20 to unknown etiologic factors in our population. A de novo RB1 deletion along with transmitted RB1 point mutation from an asymptomatic parent was identified as a unique predisposing RB1 mutation chimerism in a URB case that later evolved to bilateral retinoblastoma (BRB). The predisposing mutations such as del (13q), RB1 mono-allelic deletion and RB1 point mutation in sporadic Rb were de novo as well as transmitted mutations from asymptomatic/symptomatic parents. The RB1 mutation incidence was comparatively higher (25%) in nonfamilial Rb with emphasis on high prevalence in sporadic URB (18% versus 0%-9% in the literature series). The present studies demonstrated the efficacy of a multitechnique approach to detect various types of constitutional RB1 mutations such as RB1 deletion, deletion mosaicism, point mutation, mutation chimerism in patients of symptomatic/asymptomatic parents.
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Affiliation(s)
- M N Bamne
- Cancer Cytogenetics Laboratory, Tata Memorial Hospital, Parel, Mumbai, India
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Dalamón V, Surace E, Giliberto F, Ferreiro V, Fernandez C, Szijan I. Detection of germline mutations in argentine retinoblastoma patients: low and full penetrance retinoblastoma caused by the same germline truncating mutation. BMB Rep 2004; 37:246-53. [PMID: 15469703 DOI: 10.5483/bmbrep.2004.37.2.246] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Constitutional RB1 gene mutations were studied in a series of 21 families with unilateral and bilateral retinoblastoma patients. Peripheral blood lymphocytes were analyzed by "exon by exon" PCR-heteroduplex and sequencing. Mutations were identified in 6 (29%) of the patients. One mutation corresponded to an intronic polymorphism in g.174351T > A. The other five mutations resulted C to T exonic transitions, four were CGA sequences (g.65386, g.150037 in two patients, and g.162237), creating stop codons and presumably truncated proteins. The fifth one was new and resulted in alanine to valine substitution (g.73774). Two patients had the same the germline truncated mutation (g.150037C > T), one with a familial bilateral early onset retinoblastoma and one with a sporadic unilateral late onset retinoblastoma. The later type has not been previously described. This finding is discussed in the genotype/phenotype correlation context. Additionally, a single nucleotide change was found in six studied samples, where a C to T homozygous transversion was identified in intron 26 (IVS26 + 28). It is worthy the non concordance of the nucleotide with the published sequence. This analysis proved to be a useful method for the detection of mutations in the RB1 gene, and contributed to the adequate genetic counseling to patients and relatives.
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Affiliation(s)
- Viviana Dalamón
- Catedra de Genetica y Biologia Molecular, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Argentina.
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Leone PE, Vega ME, Jervis P, Pestaña A, Alonso J, Paz-Y-Miño C. Two new mutations and three novel polymorphisms in the RB1 gene in Ecuadorian patients. J Hum Genet 2003; 48:639-641. [PMID: 14625809 DOI: 10.1007/s10038-003-0092-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2003] [Accepted: 09/30/2003] [Indexed: 11/28/2022]
Abstract
RB1 is the gene responsible for retinoblastoma, the most common malignant intraocular tumor of infancy and early childhood. There are no reports about this gene in Ecuadorian populations, and only a few studies have been published in Latin America about this subject. There is a spectrum of more than 370 mutations described in the RB1 gene mutation database (http://www.d-lohmann.de/Rb/mutations.html), and alterations have been found in 25 of the 27 exons. During the exon-by-exon analysis of 31 tumor and blood samples from Ecuadorian patients, we found two new mutations and three novel polymorphisms. One of the polymorphisms is located in intron 26 where no alterations of the gene have been described previously. The polymorphisms were found in all of the patients' tumor samples, but not in normal population, suggesting there might be a relationship between these polymorphisms and the development of retinoblastoma in the Ecuadorian population.
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Affiliation(s)
- Paola E Leone
- Laboratorio de Genética Molecular y Citogenética Humana, Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, PO Box 17-1-2184, Quito, Ecuador.
- Unidad de Genética, Facultad de Medicina, Pontificia Universidad Católica del Ecuador, Quito, Ecuador.
| | - María Elena Vega
- Unidad de Genética, Facultad de Medicina, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Paola Jervis
- Unidad de Genética, Facultad de Medicina, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Angel Pestaña
- OncoLab, Unidad de Biología Molecular y Celular del Cáncer, Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Madrid, Spain
| | - Javier Alonso
- OncoLab, Unidad de Biología Molecular y Celular del Cáncer, Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Madrid, Spain
| | - César Paz-Y-Miño
- Laboratorio de Genética Molecular y Citogenética Humana, Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador, PO Box 17-1-2184, Quito, Ecuador
- Unidad de Genética, Facultad de Medicina, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
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Richter S, Vandezande K, Chen N, Zhang K, Sutherland J, Anderson J, Han L, Panton R, Branco P, Gallie B. Sensitive and efficient detection of RB1 gene mutations enhances care for families with retinoblastoma. Am J Hum Genet 2003; 72:253-69. [PMID: 12541220 PMCID: PMC379221 DOI: 10.1086/345651] [Citation(s) in RCA: 202] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2002] [Accepted: 10/11/2002] [Indexed: 01/12/2023] Open
Abstract
Timely molecular diagnosis of RB1 mutations enables earlier treatment, lower risk, and better health outcomes for patients with retinoblastoma; empowers families to make informed family-planning decisions; and costs less than conventional surveillance. However, complexity has hindered clinical implementation of molecular diagnosis. The majority of RB1 mutations are unique and distributed throughout the RB1 gene, with no real hot spots. We devised a sensitive and efficient strategy to identify RB1 mutations that combines quantitative multiplex polymerase chain reaction (QM-PCR), double-exon sequencing, and promoter-targeted methylation-sensitive PCR. Optimization of test order by stochastic dynamic programming and the development of allele-specific PCR for four recurrent point mutations decreased the estimated turnaround time to <3 wk and decreased direct costs by one-third. The multistep method reported here detected 89% (199/224) of mutations in bilaterally affected probands and both mutant alleles in 84% (112/134) of tumors from unilaterally affected probands. For 23 of 27 exons and the promoter region, QM-PCR was a highly accurate measure of deletions and insertions (accuracy 95%). By revealing those family members who did not carry the mutation found in the related proband, molecular analysis enabled 97 at-risk children from 20 representative families to avoid 313 surveillance examinations under anesthetic and 852 clinic visits. The average savings in direct costs from clinical examinations avoided by children in these families substantially exceeded the cost of molecular testing. Moreover, health care savings continue to accrue, as children in succeeding generations avoid unnecessary repeated anaesthetics and examinations.
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Affiliation(s)
- Suzanne Richter
- Faculty of Medicine, University of Western Ontario, Toronto, Ontario, Canada
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Abstract
Two affected HEXA alleles were found in an Israeli Druze Tay-Sachs child born to first-cousin parents. His paternal allele contained two adjacent changes in exon 5: delta496C, which resulted in a frameshift and premature termination codon 96 nucleotides downstream, and 498C-->G, a silent mutation. The maternal allele had a 835T-->C transition in exon 8 (S279P). Phosphoimaging quantitation of the parents' RNAs showed that the steady-state levels of mRNAs of the mutant exons 5 and 8 were 5% and 50%, respectively, of normal levels. The exon 5 mutated allele with the premature translation termination resulted in severe deficiency of Hex A. Transient expression of the exon 8 mutated alpha-chain cDNA in COS-1 cells resulted in deficiency of enzymatic activity. The child exhibited a late-infantile-type disease.
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Affiliation(s)
- L Drucker
- Department of Human Genetics, Sackler School of Medicine, Tel Aviv University, Israel
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14
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Abstract
Men have more germ-line cell divisions than women. Does this lead to a higher mutation rate in males? Most estimates of the proportion of mutations originating in men come either from direct observation of disease-inducing mutations or from analysis of the relative rate of evolution of sex-linked and autosomal genes in primates. The latter mode of analysis has also been applied to other mammals, birds and files. For unknown reasons, this method produces contradictory results. A majority of estimates using the best direct methods in humans indicate a male bias for point mutations, but the variance in estimates is high. It is unclear how the evolutionary and direct data correspond and a consensus as to the extent of any male bias is not presently possible. While the number of germ-line cell divisions might contribute to differences, this by no means accounts for all of the data.
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Affiliation(s)
- L D Hurst
- Department of Biology and Biochemistry, University of Bath, UK.
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15
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Harbour JW. Overview of RB gene mutations in patients with retinoblastoma. Implications for clinical genetic screening. Ophthalmology 1998; 105:1442-7. [PMID: 9709755 DOI: 10.1016/s0161-6420(98)98025-3] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
OBJECTIVE This study aimed to determine the distribution of germline mutations in the retinoblastoma (RB) gene in patients with retinoblastoma to design more effective genetic testing. DESIGN A meta-analysis. PARTICIPANTS 192 cases identified from literature. METHODS All identifiable reported cases of bilateral retinoblastoma, which included DNA sequence analysis of the RB gene, were reviewed. MAIN OUTCOME MEASURE Type of genetic mutation. RESULTS Among 192 patients with retinoblastoma with identifiable germline mutations in the RB gene, the DNA alteration was a nonsense mutation in 83 (43%), frameshift in 67 (35%), intron mutation in 23 (12%), missense mutation in 11 (6%), in-frame deletion in 5 (3%), and promoter mutation in 3 (2%). Mutations were distributed throughout 24 of the 27 exons of the RB gene with no single mutational "hotspot." Exons 8, 17, 18, and 23 were involved most often, and 189 (98%) of the mutations were predicted to affect the RB large pocket domain. CONCLUSIONS A single genetic test is unlikely to detect all germline RB gene mutations in patients with retinoblastoma because of the variety of types and locations of mutations that occur. However, a series of complementary tests may be able to rapidly detect mutations based on the observation that most mutations alter the protein size and disrupt the large pocket domain.
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Affiliation(s)
- J W Harbour
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110-1093, USA
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