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Test Identifier Information

Registration CodeMUTA 24

Coding regions of the 27 exons of the RB1 gene are amplified by PCR and analysed by DNA sequencing. 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. 

Diagnostic Use / Indications

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.

External Price$890.00(Exclusive of GST)

Specimen Collection

Patient Specimen5.0 mL EDTA(Lavender) blood; fresh tumour tissue
Paediatric Specimen0.5 mL - 1.0 mL EDTA(Lavender) blood
Sample Delivery to LabSame day or overnight courier, ambient

CHLabs Laboratory

DepartmentBiochemistry - Molecular Pathology
Contact Details Email Email
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Contact Phone Number03 3640 548
Test Availability9am-5pm, Monday to Friday
Turnaround TimeWithin 6 weeks
Uncertainty of Measurement

 Automated bidirectional DNA sequencing has an analytical sensitivity and specificity of >99%. Note that the lower limit of variant detection of sequencing analysis is ~10%, this is important to consider in the case of mosaicism, mitochondrial, and somatic variation that is not expected to be present at 50% or 100%.  This analysis will not detect variants located within intronic regions, except at the intron-exon boundaries.

Additional Information
  1. This test requires nucleated cells. Please do not centrifuge or freeze blood samples.
  2. Genomic DNA must be extracted from the specimen prior to testing. This incurs an additional charge (see GDNA). 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
Delphic Number Test Number7312

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