Overview of rb gene mutations in patients with retinoblastoma: Implications for clinical genetic screening

doi:10.1016/S0161-6420(98)98025-3

Ophthalmology

Volume 105, Issue 8, 1 August 1998, Pages 1442-1447

Presented in part at the Annual Meeting of the American Academy of Ophthalmology, San Francisco, California, October 1997.

https://doi.org/10.1016/S0161-6420(98)98025-3 Get rights and content

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.

Section snippets

Materials and methods

An extensive literature review was undertaken to identify scientific articles published in the English language that report germline (constitutional) mutations in the RB gene in patients with retinoblastoma. Cases were included only if: (1) mutational analysis was performed on DNA obtained from peripheral blood or other nontumor tissue source; (2) data were derived from an original research article; (3) the exact DNA sequence alteration was reported; and (4) intron mutations occurred in

Results

Germline (constitutional) DNA mutations within the RB gene were identified in 192 patients with retinoblastoma reported in 19 scientific articles from Germany (83 patients from Germany and 4 from Argentina),11, 25, 26, 27, 28 France (45 patients),23 the United Kingdom (45 patients),16, 20, 21, 22, 24, 29, 30, 33 Japan (12 patients),18, 19, 32 and the United States (3 patients).17, 31 Eight (4%) of the patients were members of low-penetrance retinoblastoma families.16, 17, 22, 25, 31

Table 1

Discussion

One of the major goals in the treatment of patients with retinoblastoma is to improve the clinical usefulness of genetic testing for patients and their families. Despite the use of modern molecular techniques, there have been several obstacles to achieving this goal:

1.
The RB gene is very large.
2.
Mutations occur throughout the gene with no single hotspot.
3.
The available techniques for directly sequencing the gene are labor intensive and time consuming.

Several groups have used technical shortcuts to

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RB1 5́UTR contains an IRES related to cell cycle control and cancer progression
2023, Gene
Retinoblastoma gene1 (RB1) is the first tumor suppressor gene that stands as the guardian of the gate of the G₁ period and plays a central role in proliferation and differentiation. However, no reports focused on the possible internal ribosome entry site (IRES) function of the RB1 gene flanking sequence. In this study, we constructed a bicistronic reporter with the RB1 5′untranslated region (5́UTR) inserted between two reporter coding regions. We found RB1 5′UTR harbors an IRES and has higher activity in cancer cell lines than normal cells. Besides, RB1 IRES acquired the highest activity in the G₀/G₁ phase of the cell cycle, and the RB1 5′UTR mutation collected from retinoblastoma decreased IRES activity compared with RB1 5′UTR wild-type. These data indicated that RB1 IRES is a mechanism of stress regulation and is related to cell cycle control and cancer progression.
Diverse mutational spectrum in the 13q14 chromosomal region in a Brazilian cohort of retinoblastoma
2022, Experimental Eye Research
Citation Excerpt :
Children carrying germline RB1 mutations have 90% risk of developing unilateral or bilateral tumors and other non-ocular neoplasias (DiCiommo et al., 2000). Most constitutive mutations consist of one or a few nucleotide substitutions (Lohmann et al., 1996) but, in some cases, large RB1 and 13q14 deletions as well as copy number variations (CNVs) have been reported (Harbour, 1998; Lohmann, 1999). Identification of the first mutational event in RB patients enables the establishment of prevention strategies, through genetic counseling of carriers and families, for other related malignancies.
Retinoblastoma is a rare childhood tumor caused by the inactivation of both copies of the RB1 gene. Early diagnosis and identification of heritable RB1 mutation carriers can improve the disease outcome and management via genetic counseling. We used the Multiplex Ligation-dependent Probe Amplification (MLPA) method to analyze the RB1 gene and flanking regions in blood samples from 159 retinoblastoma patients previously negative for RB1 point mutations via Sanger sequencing. We detected a wide spectrum of germline chromosomal alterations, ranging from partial loss or duplication of RB1 to large deletions spanning RB1 and adjacent genes. Mutations were validated via karyotyping, fluorescent in situ hybridization (FISH), SNP-arrays (Single Nucleotide Polymorphism-arrays) and/or quantitative relative real-time PCR. Patients with leukocoria as a presenting symptom showed reduced death rate (p = 0.013) and this sign occurred more frequently among carriers of two breakpoints within RB1 (p = 0.05). All unilateral cases presented both breakpoints outside of RB1 (p = 0.0075). Patients with one breakpoint within RB1 were diagnosed at earlier ages (p = 0.017). Our findings characterize the mutational spectrum of a Brazilian cohort of retinoblastoma patients and point to a possible relationship between the mutation breakpoint location and tumor outcome, contributing to a better prospect of the genotype/phenotype correlation and adding to the wide diversity of germline mutations involving RB1 and adjacent regions in retinoblastoma.
Chromosomal microarray analysis of benign mesenchymal tumors with RB1 deletion
2020, Human Pathology
Citation Excerpt :
See Supplemental Table for a full listing of genetic alterations detected in these cases. RB1, a well-known tumor suppressor gene, has been demonstrated to undergo a myriad of different alterations in disease states [24]. Germ line mutations in RB1, resulting in retinoblastoma, are primarily single-nucleotide variants [24].
Spindle cell lipomas/pleomorphic lipomas, mammary-type myofibroblastomas, and cellular angiofibromas are benign mesenchymal tumors that demonstrate histologically overlapping features but with varying anatomic locations and an uncertain etiologic relationship. These tumors have also been found to have an overlapping molecular profile with shared 13q14 deletions, which is the location of the tumor suppressor gene RB1 that encodes the retinoblastoma protein. Molecular studies thus far have largely focused on the RB1 locus, using primarily immunohistochemistry and fluorescence in situ hybridization to characterize RB1 status. However, further characterization of the molecular profile of these lesions, including genome-wide copy number variation, remains to be well defined. The goal of this study is to further characterize the specific RB1 deletions seen in spindle cell lipomas/pleomorphic lipomas, cellular angiofibromas, and mammary-type myofibroblastomas as well as to evaluate these neoplasms for additional molecular abnormalities using the OncoScan™ CNV Plus Assay, which is used for clinical use as a whole-genome copy number microarray-based assay. Ten of eleven cases demonstrated deletion of the RB1 gene with varying deletion size and breakpoints. The majority of additional genetic alterations were chromosomal losses and loss of heterozygosity with rare chromosomal gains. Although only a small subset of mesenchymal neoplasms was evaluated, the principle of creating a novel pairing of the molecular method with the tumor type represents a promising avenue for further study in a variety of tumors.
Retinoblastoma Genetics: Current Understanding and Future Directions
2020, Advances in Ophthalmology and Optometry
Citation Excerpt :
Unlike many other cancers, the genome-wide characterization of retinoblastoma epigenomes and transcriptomes is however very limited. Methodologies such as karyotyping and Southern blot were initially used in order to detect loss of RB1 at the chromosomal level [82,83]. The evolution of molecular biology methodologies, such as single-strand conformation polymorphism and denaturing high-performance liquid chromatography, made the detection of point mutations possible.
Pathology of the Conjunctiva, Orbit, Lacrimal Gland, and Intraocular Tumors
2020, Gnepp's Diagnostic Surgical Pathology of the Head and Neck, Third Edition
A large array of pathologies must be considered in the etiologic differential diagnosis of diseases affecting the ocular tissues. Understanding the most common pathologies that explain symptoms in the eye or threaten life or vision even without symptoms, knowledge of the nomenclature and its nuances used to communicate findings, and recognizing challenging differential diagnoses are key to the accurate diagnosis and treatment of ocular diseases. This chapter describes the major causes of neoplastic ocular diseases, the histopathological findings, and major differential diagnoses. This chapter is divided into three sections. The first section describes the most common benign and malignant pathologies of the conjunctiva, some of which may be challenging lesions encountered in surgical pathology practice. The second section is dedicated to pathological processes affecting the orbital tissues and lacrimal gland, providing an overview of the most common diagnoses, the differential diagnoses, and options of treatment for mass lesions that may lead to decreased vision or worse. The third section describes the most common intraocular tumors including metastasis, uveal melanoma, and retinoblastoma. A discussion on the normal histopathology of the ocular tissues in each section will allow the reader to better understand the various pathological processes. The goal of the chapter is to determine the role of pathology in informing treatment strategies for eye diseases, and to illuminate the collaboration between the pathologist and ophthalmologist.
Pediatric Oncologic Emergencies
2017, Hematology/Oncology Clinics of North America
Citation Excerpt :
Practitioners play an important role in identifying patients with no red reflex or strabismus in the newborn nursery or at routine check-ups.10 Approximately 70% of cases of retinoblastoma are unilateral11; in these cases, treatment is predominantly enucleation. When retinoblastoma is bilateral or extends beyond the orbit, radiation, chemotherapy, photocoagulation, and cryotherapy may be required to treat the tumor and preserve residual vision.8

View all citing articles on Scopus

^☆: Supported in part by a Career Development Award from Research to Prevent Blindness, Inc., and in part by NIH grant EY02687.

¹: The author has no proprietary interest in this study.

View full text

Overview of rb gene mutations in patients with retinoblastoma: Implications for clinical genetic screening1☆,

Abstract

Objective

Design

Participants

Methods

Main outcome measure

Results

Conclusions

Section snippets

Materials and methods

Results

Discussion

Am J Ophthalmol

Surv Ophthalmol

J Biol Chem

Curr Opin Cell Biol

Mortality from second tumors among long-term survivors of retinoblastoma

J Natl Cancer Inst

Genetics of retinoblastoma

Hum Genet

Unilateral retinoblastomanew intraocular tumours after treatment

Br J Ophthalmol

Cost comparison of molecular versus conventional screening of relatives at risk for retinoblastoma

Am J Hum Genet

Molecular genetic diagnosis of retinoblastoma

Semin Ophthalmol

Frequency of 13q abnormalities among 203 patients with retinoblastoma

J Natl Cancer Inst

Characterization of deletions at the retinoblastoma locus in patients with bilateral retinoblastoma

Am J Med Genet

The spectrum of RB1 germ-line mutations in hereditary retinoblastoma

Am J Hum Genet

Regions of the retinoblastoma gene product required for its interaction with the E2F transcription factor are necessary for E2 promoter repression and pRb-mediated growth suppression

Mol Cell Biol

A single amino acid substitution results in a retinoblastoma protein defective in phosphorylation and oncoprotein binding

Proc Natl Acad Sci U S A

Defective human retinoblastoma protein identified by lack of interaction with the E1A oncoprotein

Cancer Res

Oncogenic point mutations in exon 20 of the RB1 gene in families showing incomplete penetrance and mild expression of the retinoblastoma phenotype

Proc Natl Acad Sci U S A

Oncogenic germ-line mutations in Sp1 and ATF sites in the human retinoblastoma gene

Nature

Mutations in the retinoblastoma gene and their expression in somatic and tumor cells of patients with hereditary retinoblastoma

Hum Mutat

Overview of rb gene mutations in patients with retinoblastoma: Implications for clinical genetic screening¹ ☆,