All are true about Familial adenomatous polyposis except
Familial adenomatous polyposis (FAP) is defined clinically by the presence of more than 100 colorectal adenomas but is also characterised by duodenal adenomas and multiple extraintestinal manifestationsmutations in the adenomatous polyposis coli (APC) gene on the sho arm of chromosome 5. FAP is inherited as an autosomal dominant condition The lifetime risk of colorectal cancer is 100% in patients with FAP. Extracolonic manifestations of FAPEndodermal derivativesAdenomas and carcinomas of the duodenum, stomach,small intestine, thyroid, and biliary treeFundic gland polypsHepatoblastomaEctodermal derivativesEpidermoid cysts (Gardner syndrome)PilomatrixomaCongenital hyperophy of the retinal pigment epithelium (CHRPE)Brain tumours (Turcot syndrome)Mesodermal derivativesDesmoid tumoursOsteomasDental problemsRef: Bailey and Love, 27e, page: 1259
More than 100 colorectal adenomas
Multiple extraintestinal manifestations
Lifetime risk of colorectal cancer is 70-80%
Mutations in the adenomatous polyposis coli (APC) gene
G.I.T