MYH polyposis syndrome: clinical findings, genetics issues and management

Colorectal cancer (CRC) is one of the most frequent cancer in first world. Two hereditary CCR syndrome have been described: familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer. A recently described biallelic mutation of MYH, is responsible for adenomatous polyposis with an increased risk of CRC and is responsible for 30-40 % of adenomatous polyposis cases in which an APC mutation cannot be found. However, there is no clear consensus in the literature as whether a monoallelic mutation increases the risk for colorectal cancer. In addition, some authors have indicated that the spectrum of extracolonic lesions in MYH associated polyposis (MAP) might be far different from that observed in FAP and could be more similar to Lynch syndrome spectrum. In this review we are going to describe some general and specific aspects of MAP, including genetic topics, clinical features, different phenotypes and strategies to reduce CCR risk.