Retinoblastoma - Deletion/Duplication Test Cost & Procedure

A malignant retinal tumour known as retinoblastoma typically affects children under the age of five. A single germline pathogenic variant in the RB1 gene that causes hereditary retinoblastoma predisposes people to the disease as well as other non-ocular tumours including pineoblastoma, osteosarcoma, soft tissue sarcoma, and melanoma.

What are Duplication and Deletion?

Searching for parts of the DNA (or pages in the book) that are absent or duplicated in either one or both copies of a given gene is known as deletion/duplication analysis. How a gene functions can be impacted by missing or duplicated sections of the gene.

Any of the following symptoms in children should raise the possibility of retinoblastoma:

• Leukocoria (white pupil) (white pupil)
• Strabismus
• eye appearance change
• decreased visual clarity

Any of the following symptoms should raise suspicions of hereditary retinoblastoma:

• Diagnosis of retinoblaretinoblastomas bilateral and unilateral involvement (unifocal and multifocal)
• the retina
• a history of retinoblastoma in the family

When a person has both retinoblastoma/retina and a family history of the disease, it is determined that they have hereditary retinoblastoma.

• A 13q14 chromosome loss is present in about 6-8% of retinoblastoma patients, and this deletion is also linked to developmental delay and birth abnormalities.
• The approach employed for germline assays has limited sensitivity for mosaic variants, hence it should not be ordered to discover somatic mutations linked to tumours or malignancy.

It is not advised for those who have had an allogeneic bone marrow transplant or a hematologic malignancy to submit a peripheral blood sample for molecular genetic testing.

To properly understand test results, cultivated fibroblasts must be tested.

Methodology:

The following steps are used to carry out this test:

• A probe-based hybrid capture enrichment method is used to isolate specific genomic areas, primarily coding exons and exon-intron boundaries, from the targeted genes' retrieved genomic DNA.
• Massively parallel sequencing (MPS; also known as next-generation sequencing; abbreviated NGS) is used to sequence enriched DNA.
• This is followed by paired-end read alignment and variant calling using a customized bioinformatics pipeline.
• A detection algorithm for significant deletions and duplications (single exon-level or greater) is part of the workflow.
• Sanger sequencing is done when required to fill in low-coverage areas and, in some cases, to confirm variant calls.
• When sample quality and technical conditions permit, large deletion/duplication calls produced by MPS are verified by an orthogonal exon-level microarray.