Inherited cancer syndromes

Multiple polyposis syndromes
Familial adenomatous polyposis (FAP) follows autosomal
dominant inheritance and carries a high risk of malignancy
necessitating prophylactic colectomy. The presentation may be
with adenomatous polyposis as the only feature or as the
Gardener phenotype in which there are extracolonic
manifestations including osteomas, epidermoid cysts, upper
gastrointestinal polyps and adenocarcinomas (especially
duodenal), and desmoid tumours that are often
retroperitoneal. Detecting congenital hypertrophy of the
retinal pigment epithelium (CHRPE), that occurs in familial
adenomatous polyposis, has been used as a method of early
identification of gene carriers. The adenomatous polyposis coli
(APC) gene on chromosome 5 responsible for FAP has been
cloned. Mutation detection or linkage analysis in affected
families provides a predictive test to identify gene carriers.
Family members at risk should be screened with regular
colonoscopy from the age of 10 years.