Retinoblastoma: RB1 gene analysis

Test Identifier Information

Coding regions of the 27 exons of the RB1 gene are analysed using an AmpliSeq-for_illumina custom panel on an Illumina MiSeq instrument. In some cases a pathogenic mutation is not detected by the sequencing analysis and further investigations are required - this may involved MLPA to screen for deletion mutations, methylation analysis, or sequencing of the mRNA transcript. 

Retinoblastoma is a malignant tumour that originates from embryonic retinal cells. It is the most common intra-ocular cancer of infants with a frequency of 1 in 18000 live births. Early genetic diagnosis and focal treatment, while lesions can still be ablated, is central to an effective management strategy. Inheritance of a mutation in one copy of the RB1 gene leads to a hereditary predisposition to retinoblastoma. Tumour development is initiated when a mutation of the second allele occurs. Somatic RB1 mutations in embryonal retinal tissue lead to non-hereditary unilateral retinoblastomas from a solitary focus. However, some unilateral tumours are the result of inherited mutations that confer risk to the affected individual with a risk of subsequent malignancy. Germline mutations generally result in bilateral disease and/or multiple tumours. There is a 3% risk of an associated intracranial retinoblastoma and a high risk (6-35%) of a second non-ocular malignancy later in life, especially when external beam radiotherapy is used for ocular treatment.

Specimen Collection

CHLabs Laboratory

1. This test requires nucleated cells. Please do not centrifuge or freeze blood samples.
2. Laboratories may prefer to submit DNA for testing. Please provide a minimum of 5 micrograms of DNA at 20 nanograms/microlitre.
3. For deletion/duplication analysis of this gene refer to MLPA Testing