Retinoblastoma

Introduction

Retinoblastoma (Rb) is a malignant intraocular tumour occurring predominantly in children under 5 years. The incidence of this disease is 1 in 15,000-25,000. Approximately 35 to 45% of all Rb cases are heritable as defined by a family history and/or the presence of bilateral or multifocal tumours. In familial cases, the disease is autosomal dominant with high penetrance (90%). The remainder usually present as unilateral solitary tumours, with approximately 15% of these unilateral cases having a germline mutation. The gene for retinoblastoma (RB1) is localised at 13q14.

Referral information

Mutation screening in the blood of index cases with a family history or bilateral Rb. Mutation screening in tumours from cases of sporadic unilateral Rb. Pre-symptomatic testing of relatives of an index case with a previously identified RB1 mutation. Prenatal diagnosis where a germline mutation has been identified in a parent.. Linkage analysis for families at risk in whom no mutations have been identified.

Technical information

Mutation screening of all coding exons and promoter region of RB1 is by Next Generation sequencing using MiSeq sequencing by synthesis technology. Screening using this method has been validated to detect point mutations and small insertions/deletions to 5%.  Dosage analysis by MLPA is used to screen for the presence of large deletions or duplications. Intragenic and flanking RB1 markers are used to perform linkage analysis in families in whom no mutations have been identified. Intragenic RB1 markers are used to test for loss of heterozygosity in tumour material.  Methylation specific PCR assay and methylation sensitive MLPA are used to detect RB1 promoter hyper-methylation in tumour samples.

Price & reporting times

This service is funded by the National Commissioning Group for NHS referrals for patients from England. In other cases please contact the lab for prices.

Test Price (£ ex VAT) TRT
Mutation scanning POA 52 days
Single mutation test POA 14 days
Prenatal diagnosis POA 3 days
Urgent/Predictive single mutation screen POA 10 days

Test validation & quality assurance - information for users

In our series NGS sequence analysis and deletion/duplication analysis detects >90% of germline mutations in patients with bilateral RB. The laboratory is UKAS assessed against ISO 15189 standards.

Sample requirements

Pre-natal: amniotic fluid (minimum 15ml)/chorionic villus biopsy (CVB) (minimum 10mg) sample plus 4ml EDTA maternal blood sample

Post-natal: 4ml EDTA blood sample, fresh retinoblastoma tissue samples

Referral guidelines

Please see our referral guidelines for more information.

OMIM Number(s) - 180200

Gene(s) - RB1

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