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In about 5% of all cases, colorectal cancer (CRC) is associated with a dominantly or recessively inherited syndrome due to mutations in high penetrance genes. The most common syndrome is Lynch syndrome (hereditary non-polyposis colorectal cancer (HNPCC)), which is characterised by the development of CRC, endometrial cancer and various other cancers. 1 The syndrome is caused by a mutation in one of the mismatch repair (MMR) genes: MLH1 , MSH2 , MSH6 and PMS2 . Familial adenomatous polyposis (FAP) is another well-described inherited syndrome, which is responsible for 1% or less of all CRC cases. 2 This syndrome is characterised by the development of hundreds to thousands of adenomas in the colorectum as well as several extracolonic manifestations. Almost all patients will develop CRC if they are not identified and treated at an early stage. 3 Approximately 8% of families with FAP display an attenuated form of FAP characterised by the development of fewer adenomas and CRC at a more advanced age. 4 The syndrome, when inherited in an autosomal dominant manner, is caused by mutations in the APC gene. This gene plays a central role in the development and homeostasis of the intestine and many other tissues. Recently another polyposis gene has been identified, the MUTYH gene, in which bi-allelic mutations cause an autosomal recessive pattern of inheritance. 5 This form of polyposis is usually referred to as MUTYH -associated polyposis (MAP).
In April 2006 and February 2007, a workshop was organised for a group of European experts on hereditary gastrointestinal cancer. The main purpose was to develop guidelines for the clinical management of the most common inherited forms of CRC and to establish collaborative studies. A total of 31 experts from nine European countries participated in the workshops. These experts included clinical and molecular geneticists, surgeons, gastroenterologists and a pathologist all involved in the management of hereditary CRC. Prior to the meetings, key questions for important management issues were identified and a literature search was performed in order to address these questions and to elaborate guidelines in the light of the most recent knowledge. Here we report the outcome of the discussion with respect to FAP. Search terms included familial adenomatous polyposis (FAP), MUTYH -associated polyposis (MAP), APC gene and M(UT)YH gene....