Colon Cancer Risk in US Traced to Common Ancester

Carriers of specific genes
crossed the ocean; © Pixelio.de

Researchers from Huntsman Cancer Institute (HCI) at The University of Utah have discovered a founder mutation — a mutation that has been traced from many individuals in the present-day population back to a common ancestor — which may contribute to a significant percentage of colon cancer cases in the United States.

The researchers studied two large families, one in Utah and one in New York, that both carry a specific genetic mutation responsible for increased risk of colorectal cancer. They discovered that the two families share common ancestors — a couple who came to America from England in the 1630s, about the time of the Pilgrims.

The mutation causes a condition called attenuated familial adenomatous polyposis (AFAP). Without proper clinical care, people with the AFAP mutation have a greater than 2 in 3 risk of colon cancer by age 80, compared to about 1 in 24 for the general population. Yet the cancer can be prevented with proper screening and care.

“Knowing one has the condition can be life-saving,” Deborah Neklason, Ph.D., a University of Utah research assistant professor says. “Not only are affected individuals at greater risk then 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 this study has more than 7,000 descendants spanning nine generations recorded in the Utah Population Database (UPDB). Known individuals in this one family account for 0.15 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 over 5,000 reported between 1996 and 2003.

But after previous research identified this family as affected by AFAP, aggressive education and clinical intervention resulted in only one mutation carrier in the family being diagnosed with colon cancer during those years.

MEDICA.de; Source: University of Utah Health Sciences