Our Tests

Three-gene Carrier Screening Panel (CF, SMA and Fragile X)

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Purpose

Carriers of cystic fibrosis (CF), spinal muscular atrophy (SMA) and Fragile X syndrome (FXS) are common in the Australian population; however most carriers are not aware of a history of a genetic disorder in their family.

Current guidelines recommend screening for common genetic disorders, including CF, SMA and FXS, may be offered to all women prior to pregnancy.

Clinical Utility

The result provided will indicate whether a mutation was found, and the implication for the patient:

Test result Interpretation
Carrier for CF or SMA Individual is at increased risk of having affected children. Genetic counselling and testing of reproductive partner is recommended.
Carrier for FXS Females Individual is at increased risk of having affected children. This result also has potential medical implications for the individual being tested. Genetic counselling is recommended.
Carrier for FXS Males Carrier testing of males should be considered carefully. Male mutation carriers are not considered to be at risk of having children with FXS; however their daughters will inherit a premutation and be at risk of having affected children themselves. This result also has potential medical implications for the individual being tested. Genetic counselling is recommended.
Carrier status for CF, SMA and FXS unlikely A mutation was not detected but the possibility that the patient is a carrier cannot be excluded.

It is important to understand no carrier screen is able to detect every mutation that causes CF, SMA and FXS, nor will it identify carriers of other genetic conditions. Therefore, a “no mutation” result does not eliminate the risk to the patient of having a child affected with a genetic disorder.

Our clinical and scientific experts have selected the most common mutations and best technology available to detect the vast majority the relevant mutations for these three most common inherited conditions.

Depending on the results provided, referral for genetic counselling and discussion of reproductive options may be appropriate.  A list of private and public providers of clinical genetics and genetic counselling services is available from Sonic Genetics on request.

Genes

CFTR, FMR1, SMN1

Test Method

CF: Analysis of the CFTR gene for 50 common mutations (including the 5T variant).

SMA: Copy number analysis of the SMN1 gene by MLPA.

FXS: Sizing and triplet repeat primed PCR to detect expansion of the CGG repeat region in the FMR1 gene.

Test Ordering

This test can be requested by any medical practitioner.

4 mL blood in EDTA (separate tube required). 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.

Special Instructions

Please note whether or not the patient has a family history of CF, FXS or SMA on the referral form. If there is a family history, please provide as much information as possible about the family pedigree and any previous testing with results (if available) that has been performed for other family members.

Price

$400

The cost of the full Three-gene Carrier Screen is $400 or you may choose to test only CF and SMA or FXS for the same fee.

Medicare Rebate

This test is not rebated by Medicare. The laboratory assumes that the patient or client has provided informed financial consent for the test.

Turnaround Time

10 business days