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Genetic testing

Genetic testing involves carrying out a blood test to look for an affected gene or genetic alteration

Genetic testing involves carrying out a blood test to look for an affected gene or genetic alteration that may be responsible for causing bowel polyps (known as diagnostic genetic testing). Some patients are referred having had genetic testing in their local centre whilst others are referred with multiple bowel polyps and will receive genetic counselling and testing at their initial appointment (if appropriate).

If we are able to locate the gene responsible for causing the bowel polyps then this is useful as it means family members can also be tested for the genetic alteration and if positive will be screened accordingly (known as predictive genetic testing). In around 20% of patients with multiple bowel polyps, however, we are unable to locate the gene responsible. In this situation, we will make a clinical diagnosis, based on the number and type of polyps found. For these patients, family members cannot have a blood test to predict whether they will also grow bowel polyps. In this situation, family members will be advised to undergo endoscopic screening.