Genetic testing for polyposis: practical and ethical aspects.

The three autosomal dominant inherited polyposis syndromes, familial adenomatous polyposis, juvenile polyposis, and Peutz-Jeghers polyposis predispose to colorectal cancer as does hereditary non-polyposis colorectal cancer syndrome. Uncovering the genetic background of these four cancer traits provides the possibility for genetic testing of the family members of an affected patient. Before testing identification of the underlying family specific pathogenic mutation is mandatory. This is possible in about 60% to 95% of families. Endoscopic surveillance can be safely discontinued in mutation negative family members and surveillance or prophylactic surgery can be targeted to mutation positive members alone. Testing requires genetic counselling and written informed consent to prevent misunderstanding and to minimise untoward effects such as anxiety. Permanent surveillance and adequate prophylactic treatment for all mutation positive subjects and families is best ensured in national or regional polyposis registries with the capacity to take care of long term follow up from generation to generation.