Issue: May 10, 2013
March 25, 2013
2 min read
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Retinoblastoma not linked solely to RB1 mutations, study finds

Issue: May 10, 2013
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Some cases of retinoblastoma may occur due to amplification of the MYCN oncogene rather than mutation of both alleles of the RB1 retinoblastoma suppressor gene, a study found.

Perspective from Carol L. Shields, MD

In such nonhereditary cases, children may not be at heightened risk of retinoblastomas in the other eye, future cancers or further familial risk, the study authors wrote.

Researchers in the multicenter study analyzed 1,068 unilateral non-familial retinoblastoma tumors, comparing genomic copy number, RB1 gene expression and protein function, retinal gene expression, histological features and clinical data between tumors with no evidence of RB1 mutations and those with mutations in both alleles.

 No RB1 mutations were observed in 29 tumors (2.7%), and 15 of those demonstrated high-level MYCN oncogene amplification.

Subjects in the study without RB1 mutation and with MYCN amplification tended to have larger and more aggressive tumors that included invasion into the optic nerve when compared with subjects of similar age with RB1 mutations, who tended to need active surveillance to discover the smaller tumors.

The authors predicted 18% of children diagnosed with non-familial unilateral retinoblastoma before the age of 6 months will have no RB1 mutations and MYCN amplification.