No 10 Laboratory Medicine Newsletter 1995, Vol. The disease state is inherited in an autosomal dominant manner with high penetrance.
Polyps usually develop by the second or third decade of life.
In rare cases, polyps may appear before 10 years or beyond 40 years of age. In addition to disease in the colon and rectum, some FAP patients may present with osteomas, epidermoid cysts, desmoid tumors, other gastrointestinal tumors, and hypertrophy of the retinal pigment epithelium . Gardner's Syndrome and Turcot's Syndrome, previously considered distinct clinical entities, are now understood to be FAP variants with additional extracolonic manifestations. Interestingly, FAP demonstrates a bimodal distribution with respect to severity and age of onset . Colons of 'profuse' patients exhibit greater than 5000 polyps while 'sparse' cases are defined by 100-2000 polyps.