Dataset Information

Unilateral retinocytoma associated with a variant in the RB1 gene.

ABSTRACT: BACKGROUND:Retinocytoma is a rare benign retinal tumor associated with variants in the RB1 gene. Ophthalmoscopic features can include a translucent retinal mass, calcification, retinal pigment epithelial alteration and chorioretinal atrophy. METHODS:Detailed ophthalmological examinations were performed in a Chinese patient with retinocytoma and his daughter with bilateral retinoblastoma. Sanger sequencing was performed to detect RB1 genetic variants in the patient, his daughter and tumor tissue from his daughter. RESULTS:A 33-year-old man presented with poor vision and strabismus in the right eye since childhood. Fundus examination revealed a round yellow-white lesion stretching from the nasal side of the optic disc to the temporal periphery of the right eye. Sequencing result identified a reported variant (c.658C>G, p.Leu220Val) in the RB1 gene (NM_000321.2) of DNA extracted from peripheral blood of the patient and his daughter. The missense variant was also found in the tumor tissue from his daughter. CONCLUSIONS:We report detailed clinical features and genetic analysis of a case with unilateral retinocytoma. Retinocytoma has a wide range of clinical phenotypes; genetic testing is therefore a useful tool for the diagnosis of atypical cases.

SUBMITTER: Wu S

PROVIDER: S-EPMC7196460 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Unilateral retinocytoma associated with a variant in the RB1 gene.

Wu Shijing S Zou Xuan X Sun Zixi Z Zhu Tian T Wei Xing X Sui Ruifang R

Molecular genetics & genomic medicine 20200129 4

<h4>Background</h4>Retinocytoma is a rare benign retinal tumor associated with variants in the RB1 gene. Ophthalmoscopic features can include a translucent retinal mass, calcification, retinal pigment epithelial alteration and chorioretinal atrophy.<h4>Methods</h4>Detailed ophthalmological examinations were performed in a Chinese patient with retinocytoma and his daughter with bilateral retinoblastoma. Sanger sequencing was performed to detect RB1 genetic variants in the patient, his daughter an ...[more]

PMID: 31997559

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Project description:BACKGROUND: Syndromic forms of osteosarcoma (OS) account for less than 10% of all recorded cases of this malignancy. An individual OS predisposition is also possible by the inheritance of low penetrance alleles of tumor susceptibility genes, usually without evidence of a syndromic condition. Genetic variants involved in such a non-syndromic form of tumor predisposition are difficult to identify, given the low incidence of osteosarcoma cases and the genetic heterogeneity of patients. We recently mapped a major OS susceptibility QTL to mouse chromosome 14 by comparing alpha-radiation induced osteosarcoma in mouse strains which differ in their tumor susceptibility. METHODS: Tumor-specific allelic losses in murine osteosacoma were mapped along chromosome 14 using microsatellite markers and SNP allelotyping. Candidate gene search in the mapped interval was refined using PosMed data mining and mRNA expression analysis in normal osteoblasts. A strain-specific promoter variant in Rb1 was tested for its influence on mRNA expression using reporter assay. RESULTS: A common Rb1 allele derived from the BALB/cHeNhg strain was identified as the major determinant of radiation-induced OS risk at this locus. Increased OS-risk is linked with a hexanucleotide deletion in the promoter region which is predicted to change WT1 and SP1 transcription factor-binding sites. Both in-vitro reporter and in-vivo expression assays confirmed an approx. 1.5 fold reduced gene expression by this promoter variant. Concordantly, the 50% reduction in Rb1 expression in mice bearing a conditional hemizygous Rb1 deletion causes a significant rise of OS incidence following alpha-irradiation. CONCLUSION: This is the first experimental demonstration of a functional and genetic link between reduced Rb1 expression from a common promoter variant and increased tumor risk after radiation exposure. We propose that a reduced Rb1 expression by common variants in regulatory regions can modify the risk for a malignant transformation of bone cells after radiation exposure.

Dataset Information

Unilateral retinocytoma associated with a variant in the RB1 gene.

Publications

Unilateral retinocytoma associated with a variant in the RB1 gene.

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