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20q deletion FISH

Test category:

Oncology - Leukaemia

Use of test


Chromosomal abnormalities resulting in deletion of part of the long arm of Chromosome 20 (20q) can occur in myeloid neoplasms, including acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS). These abnormalities can have diagnostic and prognostic implications.


In patients with AML, deletion of 20q is associated with relatively poor prognosis, often occurring as part of a complex karyotype.

In patients with MDS, deletion of 20q (as the sole cytogenetic abnormality) is associated with a favourable prognosis.

Ethical considerations:

This is an assay for non-heritable mutations. It does not raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.


Fluorescent in situ hybridisation (FISH) analysis, using probes within the region of 20q commonly deleted in AML/MDS. This interphase FISH test has a cut off at 5%. A low level of positive cells may be due to overlap of the two signals. Studies of normal controls indicate that this level is less than 5%. Small abnormal populations may therefore not be detectable.

Requesting the test


This test is usually requested by a haematologist or oncologist. In the investigation of myelodysplasia, it is usually requested as part of the Myelodysplastic syndrome FISH panel

Sample required:

0.5 mL bone marrow in transport media (or 10 mL blood in lithium heparin if blasts >10%).

To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.

We recommend that the patient or another adult check the labelling of request forms and sample tubes.

Turnaround time:

5 business days.


Up to $255.

If more information is required, the requesting clinician can call our laboratory on (07) 3377 8573.


This test is not rebated by Medicare. The laboratory assumes that the patient or client has provided informed financial consent for the test.

Click here for our billing policy.