| [ Summary ] |
The APC gene was isolated as a gene responsible for familial adenomatous polyposis (FAP). Germline mutations of the APC gene have been analyzed for many patients with FAP. As a result, the genotype-phenotype correlation between APC and the clinical features of FAP-patients has gradually been elucidated. As the detection rate for APC germline mutations among FAP patients is limited to approximately 70 %, the existence of some responsible genes for colorectal polyposis has been proposed. Generally speaking, FAP patients of a family in which any APC germline mutation are not detected, tend to have a fewer number of the adenomas of the large intestine, and have the situation of skipp a generation of affected family members in an autosomal recessive inheritance manner. On the other hand, the base excision repair mechanism displays a function for repairing genomic alterations which occur via 8-oxo-Guanine generated by oxidation. MYH is a pivotal molecule of this system.
Recently, the MYH gene was recognized as the other gene responsible for FAP, especially for FAP patients with a low number of adenomas. Colorectal polyposis caused by MYH germline mutation is termed MYH-associated polyposis : MAP, as opposed to classical FAP caused by APC germilne mutations. A common trait of these patients is that this condition is inherited in an autosomal recessive inherited manner. Genetic information, which contains a diagnosis based on genetic testing, is more and more recognized to be important as a medical management tool. |