Colon Cancer Gene Traced to Arrival in United States

By Amanda Gardner
HealthDay Reporter
Wednesday, January 2, 2008; 10:00 AM

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WEDNESDAY, Jan. 2 (HealthDay News) -- Mr. and Mrs. George Fry sailed from the Old World to the New World around 1630 on a ship most likely named the William & Mary.

Along with at least two of their four children, they most certainly brought with them a unique genetic mutation for colon cancer, a new study shows.

This "founder mutation," which increases the risk for colon cancer, has now been passed on to a considerable number of the descendants of the original couple, the University of Utah researchers added.

The mutation has not been found in England, said study author Deb Neklason, meaning that it likely originated with either Mr. or Mrs. Fry. Her report is published in the January issue of Clinical Gastroenterology and Hepatology.

"It is a neat story of a so-called founder mutation, that is one that from its origin in a single individual has multiplied in a given population . . . so that today, it is carried by members of ostensibly unrelated families who yet descend from the one founder," explained Dr. Albert de la Chapelle, distinguished university professor of the Human Cancer Genetics Program at Ohio State University's Comprehensive Cancer Center. "It is usually a matter of chance whether such a mutation becomes more and more widespread with time, or whether it disappears. This phenomenon is called genetic drift. In this case, the mutation appears to have spread but perhaps not excessively so."

The ACP gene mutation identified by Neklason and her colleagues causes attenuated familial adenomatous polyposis (AFAP), a condition which results in a 69 percent greater risk of developing colon cancer by the age of 80. This is compared to a roughly one in 24 chance for the general population.

Like colorectal cancer in general, cancer resulting from the ACP mutation can be prevented with appropriate screening. But the researchers say it's not easy to detect people with the mutation through normal check-ups.

De la Chapelle was one of a group of scientists who discovered a different founder mutation in 2004, this one in the MSH2 gene, that is also responsible for an increased risk of colorectal cancer. "[The MSH2 mutation] causes regular and other cancers typical of the Lynch syndrome, and the risk is very high, whereas the APC one causes a mild form of polyposis, which does have a relatively high cancer risk," de la Chapelle noted.