Use of test
The SRY gene is a key determinant of the development of male physical characteristics in the fetus. It is usually located on the Y Chromosome. Abnormalities of gender differentiation can be due to deletion or mislocation of this gene. The test provides diagnostic information.
In an affected person, an abnormal result usually provides a genetic diagnosis and the basis for genetic counselling. Further family studies may clarify the recurrence risk in relatives.
A normal result does not exclude a genetic or heritable basis for the disorder as a number of other genes can be involved in abnormalities of gender differentiation.
These mutations are often de novo, and would not increase the risk of this disorder in siblings or other relatives. However, a parent and other relatives may carry the sme deletion and be at increased risk of having another affected child.
Analysis for the presence and chromosomal location of the gene by fluorescent in situ hybridisation (FISH).
Requesting the test
This test is usually requested by a paediatrician or clinical geneticist. A full karyotype is usually requested at the same time. Microarray testing could be considered as an alternative to FISH and karyotype, as it would be expected to detect SRY deletions as well as other clinically relevant large copy number imbalances.
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.
Please note on the request form whether the requirements of the MBS item descriptor have been satisfied. If this information is not provided, the patient will be billed as a private patient and a Medicare rebate will not be available.
15 business days for karyotype and FISH study; 3 business days for FISH alone.
This test has a Medicare rebate which, subject to the requirements of the Medicare descriptor being met, may cover all or part of the cost.
The Medicare details, including descriptor and schedule fee, are listed under MBS item 73291.