Familial adenomatous polyposis (FAP) is an autosomal dominant condition caused by a mutation in the APC tumour-suppressor gene, located on chromosome 5q21–q22. The clinical presentation includes multiple adenomatous large bowel and rectal polyps, in childhood and adolescence. The risk of colorectal carcinoma development reaches 100% in the mutation carriers. Gardner syndrome is a phenotypic variant of FAP with extracolonic manifestations such as dental anomalies, osteomas, congenital hypertrophy of retinal pigment epithelium, desmoids tumour and varieties of extracolonic cancers. Attenuated FAP is another variant, where the condition is mild with less than 100 polyps, for which mutation in either APC or in MUTYH gene is responsible.
Patients and methods
Here we present two FAP-associated families; harbouring two different germline APC gene mutations, discuss the clinical expression and therapeutic decisions for each of their members, based on the phenotypic–genotypic findings. We also describe the attitude of high-risk counselees towards genetic counselling.
Early informed medical intervention will help in better decision making and cancer prevention in the family.