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Genotype-phenotype correlation in the presentation of retinoblastoma among 149 patients. Exp Eye Res 2016; 146:313-317. [PMID: 27068507 DOI: 10.1016/j.exer.2016.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 11/21/2022]
Abstract
In this work, we describe the association between a germline RB1 mutation and disease presentation characteristics of retinoblastoma. The study evaluates a retrospective cohort of 164 of the 295 patients with retinoblastoma who were treated at a single center between 1988 and 2013 and who were referred for genetic evaluation. Peripheral blood was evaluated for RB1 mutations via Multiplex Ligation-dependent Probe Amplification (MLPA), sequencing, and detection of recurrent CpG transition mutations. Patients with an RB1 mutation were compared to patients without a mutation, regarding epidemiological factors and clinical presentation. Genetic analysis was completed for 149 patients. An RB1 mutation was identified in 76 children (51.0%) including 90.0% of the bilateral patients, and 19.8% of the unilateral unifocal patients (24.7% if we include the unilateral multifocal cases). The most common mutations were a stop codon (38.2%), a splicing error (19.7%) and a large deletion (15.8%). The mutation type correlated only with sex (Likelihood ratio, p = 0.0240) and with macular involvement (Likelihood ratio, p = 0.0591 and Fisher's exact one tail test p = 0.0459 for more macular involvement if there are germline mutations). It did not correlate with laterality, with the reason for referral, or with diagnosis age. However, identification of a mutation was more common in babies diagnosed under one year of age (Likelihood ratio, p < 0.0001). In conclusion, we were surprised that our genetic tests have also found mutations in 24.7% of patients with unilateral retinoblastoma in addition to most of the bilateral children. These unilateral patients with a germline mutation have an increased risk for other cancers throughout their lives, and their first-degree relatives have an increased risk for retinoblastoma. Therefore, genetic testing for RB1 mutation should be offered to all patients, including the unilateral cases.
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2
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Abstract
Genetic heterogeneity explains variation in predisposition for cancer. Whole-genome analysis allows risk to be quantified, giving better targeted screening and quantification of the personalized risk posed by environmental factors. Array-based approaches to whole-genome analysis are rapidly being overtaken by next-generation sequencing (NGS). In this review the different platforms currently available for NGS are compared and the opportunities and risks of this approach are discussed: including the informatics packages required and the ethical issues. Methods applicable to the personal genome machine (PGM) are given as an example of workflows.
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Affiliation(s)
- Victoria Shaw
- NIHR Pancreatic Biomedical Research Unit, Molecular and Clinical Cancer Medicine, Royal Liverpool University Hospital, 5th Floor UCD Block, Daulby Street, Liverpool, L69 3GA, UK
| | - Katie Bullock
- NIHR Pancreatic Biomedical Research Unit, Molecular and Clinical Cancer Medicine, Royal Liverpool University Hospital, 5th Floor UCD Block, Daulby Street, Liverpool, L69 3GA, UK
| | - William Greenhalf
- NIHR Pancreatic Biomedical Research Unit, Molecular and Clinical Cancer Medicine, Royal Liverpool University Hospital, 5th Floor UCD Block, Daulby Street, Liverpool, L69 3GA, UK.
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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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Abstract
Identification of hereditary factors that predispose to cancer allows targeted cancer screening and better quantification of environmental risk factors. The ability to identify which single nucleotide polymorphisms (SNPs) are associated with cancer or segregate with disease in families allows high-risk loci to be identified. In this chapter, two platforms for analysing SNPs are discussed, the Affymetrix and Illumina systems. Application of both platforms requires the same principles of good laboratory practice but there are important differences in materials and methods, which will be discussed.
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Affiliation(s)
- Julie Earl
- Division of Surgery and Oncology, University of Liverpool, Liverpool, UK
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Sánchez-Sánchez F, Ramírez-Castillejo C, Weekes DB, Beneyto M, Prieto F, Nájera C, Mittnacht S. Attenuation of disease phenotype through alternative translation initiation in low-penetrance retinoblastoma. Hum Mutat 2007; 28:159-67. [PMID: 16988938 DOI: 10.1002/humu.20394] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Hereditary predisposition to retinoblastoma (RB) is caused by germline mutations in the retinoblastoma 1 (RB1) gene and transmits as an autosomal dominant trait. In the majority of cases disease develops in greater than 90% of carriers. However, reduced penetrance with a large portion of disease-free carrier is seen in some families. Unambiguous identification of the predisposing mutation in these families is important for accurate risk prediction in relatives and their genetic counseling but also provides conceptual information regarding the relationship between the RB1 genotype and the disease phenotype. In this study we report a novel mutation detected in 10 individuals of an extended family, only three of whom are affected by RB disease. The mutation comprises a 23-basepair (bp) duplication in the first exon of RB1 (c.43_65dup) producing a frameshift in exon 1 and premature chain termination in exon 2. Mutations resulting in premature chain termination classically are associated with high penetrance disease, as message translation may not generate functional product and nonsense mediated RNA decay (NMD) frequently eliminates the mutant transcript. However, appreciable NMD does not follow from the mutation described here and transcript expression in tissue culture cells and translation in vitro reveals that alternative in-frame translation start sites involving Met113 and possibly Met233 are used to generate truncated RB1 products (pRB94 and pRB80), known and suspected to exhibit tumor suppressor activity. These results strongly suggest that modulation of disease penetrance in this family is achieved by internal translation initiation. Our observations provide the first example for rescue of a chain-terminating mutation in RB1 through alternative translation initiation.
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Affiliation(s)
- Francisco Sánchez-Sánchez
- Departamento de Genética, Facultad de Biología, Universidad de Valencia, Burjassot, Valencia, Spain.
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Alonso J, Palacios I, Gámez A, Camino I, Frayle H, Menéndez I, Kontic M, García-Miguel P, Sastre A, Abelairas J, Sarret E, Sabado C, Navajas A, Artigas M, Indiano JM, Carbone A, Rosell J, Pestaña A. Diagnóstico molecular del retinoblastoma: epidemiología molecular y consejo genético. Med Clin (Barc) 2006; 126:401-5. [PMID: 16595082 DOI: 10.1157/13086125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND AND OBJECTIVE Retinoblastoma, a prototype of hereditary cancer, is the most common intraocular tumor in children and a potential cause of blindness from therapeutic eye ablation, second tumors in germ line mutation carriers, and even death when untreated. The molecular scanning of RB1 in search of germ line mutations in 213 retinoblastoma patients from Spain, Cuba, Colombia and Serbia, has led to the detection of 106 mutations whose knowledge is important for genetic counselling and characterization of phenotypic-genotypic relations. PATIENTS AND METHOD Mutational study (PCR-sequentiation and microsatellites analysis) in patients with retinoblastoma, from Spain, Cuba, Colombia and Serbia. RESULTS 45% of mutations, including most of the frame shift (FS), missense (MS) and splicing (SP), were new, while all nonsense mutations (NS) corresponded to hypermutable sites in RB1. Germ line mutations were found in 22% of unilateral sporadic patients. The incidence of SP plus MS mutations in this group of patients was greater (p = 0.018) than in bilateral patients. The frequency of SP mutations was higher (p = 0.0003) in Spain and France than in Germany and United Kingdom, while the incidence of NS mutations was lower (p = 0.0006). SP mutations were associated with the low penetrance phenotype and were also overrepresented (p = 0.018) in patients with delayed retinoblastoma onset. CONCLUSIONS Mutational scanning of unilateral patients is important for genetic counselling and may help decipher the molecular mechanisms leading to low penetrance or expressivity. The functional characterization of mutations associated with low-penetrance or expressivity phenotypes and the molecular classification of tumors using multiple expression profiling is important for a better understanding of the retinoblastoma pathogenesis.
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Affiliation(s)
- Javier Alonso
- OncoLab, Departamento de Biología Molecular y Celular del Cáncer, Instituto de Investigaciones Biomédicas (IIB) Alberto Sols, CSIC-UAM, Madrid, Spain
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Du Corbier FA, Stentiford GD, Lyons BP, Rotchell JM. Isolation of the retinoblastoma cDNA from the marine flatfish dab (Limanda limanda) and evidence of mutational alterations in liver tumors. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:9785-90. [PMID: 16475367 DOI: 10.1021/es051367c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We have isolated a dab (Limanda limanda) homologue of the human retinoblastoma (Rb) tumor suppressor gene. The L. limanda partial Rb cDNA encodes a partial predicted protein of 753 amino acids. DNA sequence analysis with other vertebrate Rb sequences demonstrates that the L. limanda Rb cDNA is highly conserved in regions of functional importance. The sequence reported herein, combined with the high degree of conservation observed in critical domains, has also facilitated an investigation of the molecular etiology of environmentally induced liver tumor samples in a feral fish species. Mutational alterations were detected in liver adenoma samples, also in apparently "normal" regions of liver samples dissected from fish displaying adenoma, but not in normal liver samples from otherwise healthy feral fish. These results are the first reporting the appearance of Rb mutations in wild-caught fish and suggest that the molecular etiology of fish cancer appears to involve Rb-implicated tumorigenesis. The ecotoxicological relevance of the Rb mutations in feral fish liver tumors, in terms of future genome instability and possible development of a genotoxicity biomarker, is discussed.
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Affiliation(s)
- Frances A Du Corbier
- Centre for Environment, Fisheries and Aquaculture Science (CEFAS), The Nothe, Weymouth, Dorset DT4 8UB, UK
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Sivakumaran TA, Shen P, Wall DP, Do BH, Kucheria K, Oefner PJ. Conservation of theRB1gene in human and primates. Hum Mutat 2005; 25:396-409. [PMID: 15776430 DOI: 10.1002/humu.20154] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Mutations in the RB1 gene are associated with retinoblastoma, which has served as an important model for understanding hereditary predisposition to cancer. Despite the great scrutiny that RB1 has enjoyed as the prototypical tumor suppressor gene, it has never been the object of a comprehensive survey of sequence variation in diverse human populations and primates. Therefore, we analyzed the coding (2,787 bp) and adjacent intronic and untranslated (7,313 bp) sequences of RB1 in 137 individuals from a wide range of ethnicities, including 19 Asian Indian hereditary retinoblastoma cases, and five primate species. Aside from nine apparently disease-associated mutations, 52 variants were identified. They included six singleton, coding variants that comprised five amino acid replacements and one silent site. Nucleotide diversity of the coding region (pi=0.0763+/-1.35 x 10(-4)) was 52 times lower than that of the noncoding regions (pi=3.93+/-5.26 x 10(-4)), indicative of significant sequence conservation. The occurrence of purifying selection was corroborated by phylogeny-based maximum likelihood analysis of the RB1 sequences of human and five primates, which yielded an estimated ratio of replacement to silent substitutions (omega) of 0.095 across all lineages. RB1 displayed extensive linkage disequilibrium over 174 kb, and only four unique recombination events, two in Africa and one each in Europe and Southwest Asia, were observed. Using a parsimony approach, 15 haplotypes could be inferred. Ten were found in Africa, though only 12.4% of the 274 chromosomes screened were of African origin. In non-Africans, a single haplotype accounted for from 63 to 84% of all chromosomes, most likely the consequence of natural selection and a significant bottleneck in effective population size during the colonization of the non-African continents.
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Affiliation(s)
- Theru A Sivakumaran
- Division of Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
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Alonso J, Menéndez I, López A, Frayle H, Ruisánchez N, Pestaña A. Two independent RB1-inactivating mutations in peripheral blood DNA of a hereditary retinoblastoma patient. Genes Chromosomes Cancer 2004; 40:271-5. [PMID: 15139006 DOI: 10.1002/gcc.20042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We report the presence of a hemizygous inactivating germ-line RB1 mutation (a recurrent g.78250C-->T transition, resulting in a stop codon in exon 17) in peripheral blood DNA from a patient with hereditary bilateral retinoblastoma. Hemizygosity was established by sequencing that showed no traces of the wild-type C nucleotide and by quantitative real-time PCR, which showed loss of one copy of exon 17. Genotyping of the RB1 locus with several polymorphic markers delineated a maximal deletion region between g.76875 and g.99426, including exons 15-17 and a large piece (21 kb) of intron 17. The heterozygosity for the mutation found in skin fibroblasts proves that the intragenic RB1 deletion probably took place in the definitive hematopoietic lineage of the patient. The presence of a null Rb-/- genotype in the hematopoietic cell lineage suggests that the white blood cells of the proband could be useful in the investigation of the role of complementary RBI family proteins in the control of the cell cycle.
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Affiliation(s)
- Javier Alonso
- OncoLab, Unidad de Biología Molecular y Celular del Cáncer, Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-UAM, Madrid, Spain
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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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11
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Nájera C, Sánchez F, Mateu E, Prieto F, Beneyto M. [Early diagnosis of retinoblastoma: usefulness of searching for RB1 gene mutations]. Med Clin (Barc) 2001; 116:365-72. [PMID: 11333669 DOI: 10.1016/s0025-7753(01)71832-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
BACKGROUND Retinoblastoma, the intraocular malignancy most common in children,occurs in both familial and sporadic (bilateral or unilateral). Hereditary predisposition is caused by a germ-line mutation while non-hereditary is due to two somatic mutations in a retinal cell. This work was carried out in order to analyse genetically, the high number of families with some affected member and to go deep into the molecular mechanisms responsible of this pathology. PATIENTS AND METHOD 59 families with one or more affected members were analysed. Cytogenetics and with polymorphic markers studies were carried out and a search for mutations was performed in DNA from white cells and from available tumoral tissue. RESULTS In four of the 5 familial cases, the responsible mutation was established,the same as in 9 of the 13 bilateral sporadic. In the 7% of the unilateral sporadic cases, mutation was found in leucocytary DNA. Lost of heterozygosity as a second mutational event was mainly due to mitotic recombination. CONCLUSIONS Among the mutations of our series, a higher frequency of punctual mutations,responsible of the first mutational event, was observed at constitutional level. Lost of heterozygosity was the mechanism observed in the majority of the tumours.
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Affiliation(s)
- C Nájera
- Departamento de Genética. Facultad de Ciencias Biológicas. Universitat de Valencia.
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Alonso J, García-Miguel P, Abelairas J, Mendiola M, Pestaña A. A microsatellite fluorescent method for linkage analysis in familial retinoblastoma and deletion detection at the RB1 locus in retinoblastoma and osteosarcoma. DIAGNOSTIC MOLECULAR PATHOLOGY : THE AMERICAN JOURNAL OF SURGICAL PATHOLOGY, PART B 2001; 10:9-14. [PMID: 11277399 DOI: 10.1097/00019606-200103000-00003] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Linkage analysis at the retinoblastoma locus (RB1) is essential for identifying individuals at risk and to offer adequate genetic counseling in familial retinoblastoma. It can also be used to detect large deletions involving RB1, which accounts for 15% of the genetic alterations in hereditary retinoblastoma. These studies are usually carried out with lengthy Southern blot analyses of relatively uninformative restriction fragment length polymorphisms. The authors report an alternative, reliable protocol for genotyping the RB1 locus using two pairs of highly informative intragenic and flanking microsatellites linked closely to the RB1 gene, and analysis of the fluorescent-labeled polymerase chain reaction products with automatic sizing technology. This methodology has successfully identified high risk carriers in five of the five pedigrees of familial retinoblastoma studied. In addition, gross deletions affecting the RB1 gene were identified in two of 12 sporadic bilateral retinoblastomas, and loss of heterozygosity at the RB1 locus has been detected in one of three osteosarcomas using the same experimental protocol. The described protocol is simpler and faster than conventional Southern blot methodologies and can identify a larger number of informative cases.
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Affiliation(s)
- J Alonso
- OncoLab, Unidad de Biología Molecular y Celular del Cáncer, Instituto de Investigaciones Biomédicas, Madrid, Spain
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Rotchell JM, Blair JB, Shim JK, Hawkins WE, Ostrander GK. Cloning of the Retinoblastoma cDNA from the Japanese medaka (Oryzias latipes) and preliminary evidence of mutational alterations in chemically-induced retinoblastomas. Gene 2001; 263:231-7. [PMID: 11223262 DOI: 10.1016/s0378-1119(00)00566-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We have cloned a medaka homolog of the human retinoblastoma (Rb) susceptibility gene. The medaka Rb cDNA encodes a predicted protein of 909 amino acids. DNA sequence analysis with other vertebrate Rb sequences demonstrates that the medaka Rb cDNA is highly conserved in regions of functional importance. An antibody raised against an epitope of the human pRb recognizes the protein product of the medaka Rb gene, detecting a 105 kDa protein in all tissues examined and at differential levels for the stages of embryonic development studied. The sequence reported herein, combined with the high degree of conservation observed in critical domains, has also facilitated a preliminary investigation of the molecular etiology of chemically-induced retinoblastoma. The mutational alterations characterized suggest that medaka may provide a novel model and, thus, provide additional insight into the human retinoblastoma condition.
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Affiliation(s)
- J M Rotchell
- Department of Biology and Division of Comparative Medicine, Johns Hopkins University, 3400 North Charles Street, Baltimore MD 21218, USA
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