Inherited mutations in the cystic fibrosis gene (CFTR) can cause no symptoms (unaffected carrier), severe lung and pancreatic disorders (cystic fibrosis, CF), and other clinical outcomes (male infertility, bronchiectasis, or pancreatitis) depending on the number and type of CFTR mutations. About 1 in 30 people with European ancestry are CF carriers, with generally a lower risk in other ethnic groups.
This test detects common CFTR mutations which contribute to 85% of CFTR-related diagnoses in Australia. The test has implications for individuals and their family members.
A normal test result indicates that the person is unlikely to be a carrier or to have a CFTR-related disorder, but this possibility cannot be excluded.
The presence of one mutation indicates that the person is a carrier and may be at increased risk of having an affected child.
The presence of two mutations indicates that the person is likely to develop a CFTR-related disorder.
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. Use of the Sonic Genetics consent form is not mandated, but could be used to guide the discussion with the patient.
In the case of carrier testing of an unaffected child, national regulations require that the laboratory has evidence of pre-test counselling by a genetics professional and written consent.
Analysis of the CFTR gene for 50 common mutations (including the 5T variant). This assay detects approximately 85% of the mutant genes within the population. Please review the CF mutations document in Doctor resources below for detailed information.
Requesting the test
This test can be requested by any medical practitioner. However, Medicare rebates only apply to tests requested by a specialist or consultant physician and in specific clinical settings.
4 mL blood in EDTA (separate tube required). 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 the presence or absence of family history of cystic fibrosis on the referral form. If there is a family history of CF, state the specific CFTR gene mutation or "unknown". Please include a statement about patient's ethnicity, if known, as this may affect the pre-test probability of there being a detectable mutation.
There are different MBS item numbers for testing of the CFTR gene in specific clinical situations. Please review the CF Medicare update document in Doctor resources below for clarification. Please indicate the specific situation clearly on the request form.
Please note that Medicare rebates only apply to test requests from a specialist or consultant physician apart from GPs when cascade testing.