Rare syndromes and genetic testing for colorectal cancer.

The genes responsible for each of the inherited syndromes of intestinal polyposis and colorectal cancer are now known. This knowledge has led to genetic testing for syndrome diagnosis and for determining which persons in an affected family actually have the condition. Genetic testing has also allowed a more precise clinical characterization of each of the syndromes and their subtypes. Optimal application of genetic testing, proper cancer prevention, and management of nonmalignant features of each of the syndromes are the next goals. This report summarizes each of the syndromes, their genetics, and management and provides an approach for genetic testing.