MAP (MUTYH-Associated Polyposis )

Abstract

The phenotype is often undistinguishable from that of autosomal dominant familial adenomatous polyposis (FAP) caused by mutations in APC gene. The number of adenomas is often lower in MAP (from 5 to more than 100), and affected patients are often sporadic cases. Biallelic MUTYH mutations have also been detected in patients affected with early-onset colorectal cancer (CRC) without polyps and in one with more than 1000 polyps. Cancers are more frequently located in the proximal side of the colon compared to APCrelated FAP. Generally, mean age at diagnosis of MAP is 48-56 years, later than in APC-related FAP. A number of extracolonic manifestations have been observed, although their incidence is not yet well established. These include manifestations that are also associated with APC-related FAP, such as duodenal polyposis, duodenal cancer, osteomas, dental cysts and congenital hypertrophy of the retinal pigment epithelium. Breast cancer and thyroid cancer, and cutaneous tumors (pilomatricomas and sebaceous gland tumors) have also been reported. Neoplastic risk