Patients in whom no mutation is identified through this mutation protocol, may be sub-cohorts representing a different FAP pathogenesis including MYH associated polyposis and somatic cell mosaicism for APC gene mutations.
These results indicated that MYH-associated polyposis (MAP) is present in about 20% of Italian FAP/AAPC patients, in whom no germline APC mutation is detectable and showing a family history compatible with recessive inheritance, and in a small fraction of patients with colorectal adenomas in the general population.