Penetrance and expressivity of the gene responsible for the Gardner syndrome

Abstract

The Gardner syndrome is an autosomal dominant condition characterized by multiple polyposis of the colon, associated with various soft- and hard-tissue tumors. The original kindred 1st reported in the early 1950''s was updated and serves as the basis for a discussion of the penetrance and expressivity of the gene responsible for the syndrome. The family consists of 188 members spread over 6 generations, with 28 individuals clearly documented as having the syndrome. Using 2 different methods of calculating penetrance, the gene responsible was fully penetrant. This observation was confirmed by an analysis of 160 additional sibships from the literature. The expressivity of the gene is quite variable, and this is illustrated using examples from both kindred and the literature.