Also known as: SHOX FISH, Xp22 FISH« Back to test list
Deletion of the SHOX gene can cause short stature and bone malformations. There are usually two copies of the SHOX gene on the X and Y chromosomes (one copy on each). The loss of one copy results in a less severe disorder (Leri-Weill dyschondrosteosis) than loss of both copies (Langer mesomelic dysplasia). This test provides diagnostic information.
These mutations are usually de novo and do not increase the risk of this disorder in siblings or other relatives. However a parent and other relatives may carry a balanced translocation involving this chromosome region and be at increased risk of having an affected child.
In an affected person, an abnormal result is diagnostic of this microdeletion syndrome. Further family studies may clarify the recurrence risk in relatives.
A normal result does not exclude a clinical diagnosis as there are other mutations which can cause the syndrome.
Fluorescent in situ hybridisation (FISH) analysis using probes located within the SHOX gene.
This test is usually requested by a paediatrician or clinical geneticist. A full karyotype is usually requested at the same time.
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.
If the clinical diagnosis is uncertain, it may be preferable to request a microarray study rather than this specific FISH test as a microarray screens for microdeletions and duplications across all chromosomes.
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.