The Y chromosome is the smallest of the human chromosomes. It may not be possible to resolve details of a structural abnormality of the Y chromosome by conventional chromosome studies. Clarification of any structural alterations using FISH probes can provide diagnostic and prognostic information, for example, in men with azoospermia.
The test report will define the structural rearrangements of the Y chromosome and indicate the potential clinical significance of these rearrangements.
This is an assay for heritable mutations. It may raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient. The consent form (below) is not mandated, but could be used to guide the discussion with the patient.
In the case of carrier testing of an unaffected child, national regulations require that the laboratory has evidence of pre-test counselling by a genetics professional and written consent.
The FISH panel contains probes for the centromere, long and short arms of the Y chromosome.
Requesting the test
This test can be requested by any medical practitioner. The test is usually performed following identification of a Y chromosome abnormality with conventional chromosome analysis.
2-5 mL blood in EDTA and 2-5 mL blood in lithium-heparin. Specimens may be collected by the requesting practitioner or at any Sonic Healthcare collection centre (see link below).
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.