The importance of family study in the patients with familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is a well-known autosomal dominant disorder characterized by the formation of multiple adenomatous polyps of the colon. Gardner's syndrome is a variant of familial polyposis coli, and both can be associated with colonic or extracolonic benign and/or malignant tumors. It has been widely recognized that an adenocarcinoma of the colon develops in virtually all cases, usually at an earlier age, if polyps are left untreated. Families of four individuals diagnosed of FAP were surveyed and 56 relatives of the families were examined. Of these 56, 21 had multiple colon polyps, 3 of whom had early-stage adenocarcinomas. We consider that familial survey of FAP individuals can be of considerable benefit for this high-risk population due to the autosomal nature of the disease, allowing diagnosis of an associated cancer at an earlier stage.