- Patients with > 20 adenomatous colorectal polyps
- Siblings of a MUTYH biallelic mutation carrier
Testing may also be considered in patients with 10 -19 adenomatous colorectal polyps and any of the following:
- adenomatous polyps have been detected at a younger age (<50 yrs of age)
- adenomatous polyps are detected in conjunction with a synchronous colorectal cancer
- adenomatous polyps are detected in conjunction with serrated polyposis
- family history suggestive of recessive inheritance (e.g. consanguinity in the parents or sibling/s with documented adenomatous polyposis or colorectal cancer).
Such patients should be referred to a Familial Cancer Clinic for consideration of MUTYH testing.
Note: As MUTYH is autosomal recessive in inheritance, screening for monoallelic mutations is recommended for the partners of known or obligate biallelic and monoallelic mutation carriers to clarify the risk to offspring where relevant.rr
The decision to offer a genetic test should be based on the pre-test probability of identifying a heritable mutation, the performance of the test (e.g. false negative rate), and the patient's choice.