Familial - Familial cancer; Oncology - Colorectal cancer
Use of test
A proportion of individuals with a diagnosis or family history of colorectal cancer have a familial predisposition to develop these cancers due to variants in any one of several genes. The purpose of testing these genes can be categorised as follows:
diagnostic testing of one or more genes in an affected person to make a genetic diagnosis of hereditary colorectal cancer
if a variant has already been identified in the family, confirmatory testing for that specific variant can be offered to other affected relatives, potentially confirming their diagnosis of hereditary colorectal cancer
if a variant has been identified in the family, predictive testing for that specific variant can be offered to unaffected at-risk relatives, thereby clarifying their risk of developing cancer.
Sonic Genetics provides different panels of genes for testing for hereditary colorectal cancer:
Adenomatous polyposis panel (APC, MUTYH) includes genetic causes of familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP)
Non-adenomatous polyposis panel (BMPR1A, GREM1, SMAD4 & STK11) includes genetic causes of juvenile polyposis syndrome (JPS), Peutz-Jeghers syndrome (PJS) and hereditary mixed polyposis syndrome (HMPS)
Sonic Genetics also offers predictive testing for a family’s specific mutation in any of the genes listed above.
Variants in these genes can potentially cause colorectal cancer and a variety of others cancers. The requesting doctor can select the panel which meets the needs of the patient and the requirements of the MBS descriptor.
The identification of a pathogenic variant in one of these genes in an affected person can explain the personal and family history of cancers. These variants may also provide prognostic information (which varies with different genes). The test result can also indicate the risk to the patient of subsequent cancers and other clinical features.
When testing an unaffected person, the identification of a pathogenic variant indicates a relatively high risk of developing cancer. There are surveillance and intervention strategies recommended for unaffected patients with variants in the various genes tested.
Please note that interpretation of the genetic test result may be dependent on the family history and other clinical and laboratory information.
Analysis of these genes can raise significant clinical, psychological, familial and financial issues that patients should address before consenting to the test. These considerations become more complex as more genes are included in a gene panel.
Sonic Genetics offers pre- and post-test genetic counselling for these tests with a certified genetic counsellor by phone or telemedicine. This counselling is available upon a doctor’s request at either no charge or for a fee depending on the context and test being considered; please contact us for details. There is no Medicare rebate for genetic counselling. Our genetic counselling is managed as a clinical service, with letters to the requesting doctor and patient summarising the outcome.
We recognise that genetic counselling may not be required in every situation, and that other genetic counselling services are available to patients and doctors. Pre-test genetic counselling is not mandated by Sonic Genetics for test requests from a specialist. We require an indication that informed written consent has been obtained prior to performing the test.
Download the Sonic Genetics consent form. Other appropriate consent forms are accepted.
Sequencing of the coding and exon/intron boundaries of the genes included in the panel and copy number analysis of the included genes. PMS2 coverage includes exons 1 - 10.
Gene variants of unknown significance are reported.
Requesting the test
We recommend that these tests be requested by a specialist or consultant physician. Please use our dedicated Hereditary Cancer request form for both rebated and non-rebated testing. Please indicate on the request form if genetic counselling is to be provided by Sonic Genetics.
General practitioners are encouraged to refer patients to a specialist to arrange testing.
4 mL blood in EDTA (separate dedicated tube required). Specimens may be collected by the requesting practitioner or at any Sonic Healthcare pathology collection centre.
It is recommended that predictive testing be repeated on a second independently collected sample and in parallel with a positive control (sample from another relative confirmed to have the familial variant). These confirmatory tests are available at no extra cost.
We recommend that the patient or another adult check the labelling of request forms and sample tubes.
Please indicate whether the patient has a personal history of cancer, details of the family’s variant (if known), and whether the request meets the requirements for rebated testing.
Requests for testing for the family’s known variant must be accompanied by a copy of the laboratory report describing the mutation identified in a relative.
4-6 weeks from receipt of sample into the laboratory.
These tests have Medicare rebates which, subject to the requirements of a Medicare descriptor being met, may cover all or part of the cost. Please refer to this Technical Bulletin to determine whether your patient meets the Medicare criteria for a rebated test.
For non-rebated testing, the private fee for any of the gene panels is $1,200.
For details of the relevant Medicare rebates available including descriptor and schedule fee, please click the item of interest: