Patients with multiple colorectal adenomas are screened for germline mutations in two distinct genes, APC and MUTYH. According to the polyp number and age of onset, the phenotype of APC-mutated patients can be classified as classical familial adenomatous polyposis (FAP: more than 100 polyps, early onset) or attenuated FAP (AFAP: fewer than 100 polyps with later onset)[1-3]. The gene discussed is MUTYH; the disease is colorectal adenoma.