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KAL1 FISH, FGFR1 FISH

Test category:

Paediatric - Endocrine

Use of test

Purpose:

Kallman syndrome is a disorder of delayed puberty and impaired sense of smell. Mutations in multiple different genes can cause this syndrome. This test of two of the genes responsible has diagnostic implications.

Utility:

In an affected person, the presence of a deletion of KAL1 or FGFR1 is diagnostic of Kallman syndrome. The implications for relatives will depend on the gene involved and family history.

In an affected person, a normal result does not exclude the clinical diagnosis. There are other mutations in the KAL1 and FGFR1 genes that are not detected by this test, and other genes (many unidentified) that can cause Kallman syndrome.

Ethical considerations:

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.

Methodology:

Analysis for gene deletions using fluorescent in situ hybridisation (FISH) probes located in the KAL1 and FGFR1 genes.

Requesting the test

Ordering:

This test is usually requested by an endocrinologist, paediatrician, or clinical geneticist.

Sample required:

10 mL blood in EDTA. 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. 

>Link to Sonic Healthcare collection centres

Special instructions:

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.

>Link to Microarray test

Turnaround time:

15 business days for karyotype and FISH study; 3 business days for FISH alone.

Price:

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.

Rebate:

The Medicare details, including descriptor and schedule fee, are listed under MBS item 73291.