NCIt definition : A rare genetic syndrome with an autosomal dominant pattern of inheritance. It was
formerly called hereditary flat adenoma syndrome (HFAS) but is now recognized as an
attenuated variant of familial adenomatous polyposis (FAP). It is most commonly associated
with mutations in the APC gene specifically: exons 1-5, exon 9 and in the distal 3'
terminus. Clinical presentation occurs in the middle decades and is characterized
by the proximal development of multiple (but less than 100), non-polypoid colonic
adenomas. Clinical progression to colorectal cancer may occur later in life but the
risk is less than with classic FAP.;