Also known as: Chromosome Studies, Karyotype« Back to test list
Chromosome analysis can detect balanced and unbalanced rearrangements, and numerical changes of autosomes and sex chromosomes.
Once a potential abnormality is identified, chromosome studies of parents may be necessary to clarify the genetic diagnosis and the risks to relatives.
Please note that carrier testing of an unaffected child raises a specific pre-test issue: national regulations require that the laboratory has evidence that such a test has been associated with pre-test counselling by a genetics professional and written consent.
In an affected person, an abnormal result usually provides a genetic diagnosis and the basis for genetic counselling. A normal result does not exclude a genetic or heritable basis for the disorder as sub-microscopic changes would not be detected.
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 interpretation of the result may also be dependent on the family history and the interpretation of other studies.
Analysis of metaphase chromosomes by light microscopy. Chromosomes are counted and examined for structural and numerical abnormalities.
This test can be requested by any medical practitioner.
2-5 mL blood in lithium heparin. Specimens may be collected by the requesting practitioner or at any Sonic Healthcare pathology collection centre.
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 also recommend that the patient or another adult check the labelling of request forms and sample tubes.
Please include details of any clinical abnormalities in the patient being tested, and the results of chromosome or array studies in relatives.