FISH 1p and 19q Codeletion Test

FISH 1p and 19q codeletion test

What is 1p 19q codeletion?

It is a cytogenetic test that is used in diagnosis of oligodendrogliomas.

Oligodendrogliomas is a rare type of tumour of central nervous system (brain and spinal cord). Oligodendrogliomas are a subtype of gliomas, or primary brain tumours. They occur more often in men around the age group of 35-45years. It can be of low or high grade. The common symptoms of this tumour are:

• seizures
• headache
• weakness
• numbness
• difficulty in thinking and memory
• difficulty in proper movement and balance

Oligodendrogliomas usually have deletion of short arm of chromosome 1(1p)and long arm of chromosome 19(19q).Thus 1p19q codeletion test is a useful adjunct in the diagnosis of this rare tumour and to differentiate it from other types of glioma. Oligodendrogliomas are mainly treated by surgery, chemotherapy and radiotherapy.

Why is 1p19q codeletion test prescribed?

• The healthcare provider may prescribe this test for diagnosis of oligodendrogliomas when clinical and imaging studies are suggestive of this tumour.
• It also helps to predict the tumours response to chemotherapy and radiotherapy
• It helps to differentiate between oligodendrogliomas ,astrocytoma and tumours with hybrid morphology(mixed oligoastrocytoma)
• It helps to predict prognosis of tumour

What is a FISH test?

Fluorescent in situ hybridisation (FISH)-it is an advanced and accurate test that maps the genetic material (DNA) present on the chromosomes in cells. It helps to look at specific gene or portion of gene to detect abnormalities.

What are the components of 1p19q codeletion fish test?

It includes detection of1p36 deletion and 19q13 deletion with help of FISH probes.

Procedure and prerequisites

1p 19 q codeletion FISH test is done on tumour biopsy tissue which is taken out by inserting a needle into the tumour through a small hole in skull. Relevant clinical history/physical examination findings must be sent along with the sample. A properly filled requisition form must accompany the sample.