Using two large families one in Utah and another in New York that carry an identical gene mutation that increases risk of colorectal cancer, the Huntsman Cancer Institute-led team followed the genealogy back to discover what they call a "founder mutation," which is one shared by a common ancestor and believed to have begun with that individual, in this case one of the couple.
The HCI researchers believe it's an important finding because, over the generations, there are likely many other descendants who are at risk of the cancer and in need of early screening and education.
"This founder mutation might be related to many colon cancer cases in the United States," says Deb Neklason, Ph.D., research assistant professor at HCI and the lead author.
The findings were published today in the journal Clinical Gastroenterology and Hepatology.
The mutation is responsible for a condition called attenuated familial adenomatous polyposis (AFAP). People who have the mutation have a 67 percent chance of developing the cancer if they are not screened and the disease prevented, while just less than 4 percent of the general population develop colon cancer. AFAP also generally strikes at a younger age, around the mid-50s, compared to an average age in the early 70s for other colon cancers.
Neklason said the mutation-related colon cancer has even been found in people in their 20s, while the precursor polyps may begin appearing in the late teens.
Each child of a parent who carries the mutation has a 1 in 2 chance of inheriting it. But with proper care and education, it need not lead to cancer.
The researchers used the Utah Population Database, a massive database that links genealogical records with many public records, including those of births and deaths, as well as medical data. It's used to identify for study the families that have an unusually high incidence of cancer and other diseases, to look inheritance patterns and to find genetic mutations.
All research is done without identifiers, although data can be linked so that the individuals can be given information that's important for their health or can be invited to participate in research projects.
AFAP is not always easy to distinguish from other forms of colon cancer. Neklason says about a third of those with AFAP have just a few polyps, much like those who have sporadic colon cancer. And many people do not know their family medical history. Those with a family history of colon cancer need to be sure that their physician is aware of it and the proper screening is done.
The Utah Population Database has information on more than 7,000 descendants spanning nine generations of the Utah family. Members identified with this family account for 0.15 percent of all colorectal cancers reported in Utah between 1966 and 1995 a number that would predict eight cases of colon cancer in the family between 1996 and 2003. But they have, in fact, had only one case, which Neklason credits to identification of the AFAP risk and aggressive education and screening. She says that seven cases of colon cancer were prevented, a huge savings for the family in emotional, physical and financial terms.
Co-authors included physicians and researchers from many University of Utah departments including the institute, Oncological Sciences, Human Genetics and Medicine. It was funded by the National Cancer Institute, the Utah Department of Health, the U. and HCI.
Deb Neklason released the couple's name so people would not worry needlessly. The coupleï¿½s name is Mr. and Mrs. George Frye.
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