Their findings are published today in the journal Clinical Gastroenterology and Hepatology.
"The fact that this mutation can be traced so far back in time suggests that it could be carried by many more families in the United States than is currently known," says Deborah Neklason, a University of Utah research assistant professor and leader of the study. "In fact, this founder mutation might be related to many colon cancer cases in the United States."
The mutation causes a condition called attenuated familial adenomatous polyposis (AFAP), an inherited colorectal cancer syndrome that, over a person's lifetime, increases the chance of getting colorectal cancer by 67 percent.
The discovery, Neklason hopes, will put clinicians and the general public on the lookout for this mutation, helping those who might be at higher risk for the disease to take preventative action.
"We believe as the word gets out to the [gastrointestinal] community, they're going to find a lot of families with this particular genetic change," she said.
The researchers began studying the Utah family, which has a history of precancerous polyps and colorectal cancer, in the late 1980s. Then, in the early 1990s, they connected with a New York physician who discovered the same genetic mutation in a family there.
"We always thought these [two] families have been connected in some way. This particular mutation hasn't been reported anywhere else in the world," Neklason said.
Using familysearch.org, a genealogical Web site, Neklason was able to go back 10 generations and link the Utah and New York families - who did not wish to be identified in her study - with the English couple.
Another 13 families around the country have a similar "genetic fingerprint," Neklason said, but have not yet been definitely linked to the English couple with whom the mutation likely originated.
"Knowing one has the condition can be life-saving," Neklason says. "Not only are affected individuals at greater risk than the general population as they grow older, but precancerous polyps are often found in mutation carriers in their late teens, and colon cancer has been diagnosed in individuals in their 20s."
The Utah family in the study has more than 7,000 descendants spanning nine generations recorded in the Utah Population Database (UPDB), a shared resource for genetics research housed at the Huntsman Cancer Institute.
Researchers use UPDB to identify and study families that have higher than normal incidence of cancer or other disease, to analyze patterns of genetic inheritance and to identify specific genetic mutations.
Members of the Utah family made up 15 percent of all colorectal cancers reported in Utah from 1966 to 1995. Based on that percentage, researchers expected to see eight cases of colon cancer from this family among the more than 5,000 reported between 1996 and 2003.
After previous research identified the family as affected by AFAP, however, aggressive education and clinical intervention resulted in only one mutation carrier in the family being diagnosed with colon cancer during those years.
Neklason said people with a history of precancerous polyps and colorectal cancer in their family should talk to their health care provider about getting a genetic screening for AFAP. It could provide them - and their family members - with life-saving information.
"People need to talk with their family, learn their family cancer history, and share this information with their doctors," she said. "Doctors need to be aware of AFAP, recognize people at risk, and know the screening and treatment protocols that can prevent colon cancer from developing."
What is AFAP?
Attenuated familial adenomatous polyposis is an inherited colorectal cancer syndrome that, over a person's lifetime, increases the chance of getting colorectal cancer by 67 percent. In the case of two families, one in Utah and one in New York, it is caused by a genetic mutation traced as far back as the 1600s.