CDKN2A and Familial adenomatous polyposis: On the other hand, similar investigation of the APC gene in patients with familial adenomatous polyposis (FAP), attenuated FAP, and hyperplastic polyposis, of the BRCA1 gene in patients with familial breast cancer, and of the CDKN2A gene in patients with familial melanoma have revealed no germline mono-allelic promoter hypermethylation of any of these genes [32-34].