Genetic testing and phenotype in a large kindred with attenuated familial adenomatous polyposis.

Background & Aims: An attenuated form of familial adenomatous polyposis has been described, but the phenotype remains poorly understood.

Methods: We performed genetic testing on 810 individuals from 2 attenuated familial adenomatous polyposis kindreds harboring an identical germline adenomatous polyposis coli gene mutation. Colonoscopy was performed on mutation-positive persons.