Gene mutations that predispose people to a form of hereditary colon cancer may be found in at least one person per thousand, making it a relatively common hereditary disorder, new research shows. The mutations also increase the risk of endometrial and other cancers, with tumors usually developing before age 50. Cystic fibrosis, for example, has an incidence of 1 in 2,500. Genetic testing can reveal which family members carry the mutations, enabling them to take steps to prevent the disease. Testing all colorectal cancer patients for mutations in these genes would cost millions of dollars, making it too expensive to be practical.
Microsatellite repeats are minute regions of DNA that are repeated dozens of times.
They are thought to result from errors introduced when cancer cells replicate their DNA during cell division. It also meant that first-degree relatives of that individual might also carry one of the mutations and be at high risk of developing colorectal or endometrial cancer. Based on the results of this study, de la Chapelle recommends screening for unstable microsatellite repeats in all colorectal-cancer patients under 50 years of age who have a personal or family history of colorectal or endometrial cancer. The research reported here was funded by grants from the National Cancer Institute and the Academy of Finland.