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SCIENCE FILE

Early U.S. family passed down gene blamed for many colon cancer cases

January 05, 2008|Thomas H. Maugh II | Times Staff Writer

When Mr. and Mrs. George Frye came to the New World aboard the good ship William and Mary sometime in the early 1630s, they brought with them all of their worldly possessions, at least two of their four children -- and a deadly genetic mutation.

One of the couple had a spontaneous mutation in a gene called APC that increases the risk of developing colon cancer 17-fold, researchers from the University of Utah report.

That gene was passed down to their descendants and is now responsible for a significant number of colon cancer cases in the U.S., Dr. Deborah W. Neklason and her colleagues reported in the journal Clinical Gastroenterology and Hepatology.

Neklason's team has identified two large families, one in Utah and one in New York, whose members have a high incidence of the genetic defect, and she suspects that there are many other families as well.

"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," she said.

The genetic defect produces a condition called attenuated familial adenomatous polyposis, or AFAP. Those with the mutation have a 69% chance of developing colon cancer by the time they are 80, compared with slightly less than a 4% chance among the general population. With screening, however, the risk can be reduced sharply.

The 7,000 descendants in nine generations of the Utah family accounted for 0.15% of colon cancer cases in the state from 1966 to 1995, when the gene was first identified. Since then, only one carrier of the mutation has developed cancer -- an estimated avoidance of seven cancers.

"Preventing seven cancers may not sound like much," Neklason said. "But that is seven colon cancers that didn't devastate this family." And at an estimated cost of $50,000 per case, that was a financial savings of $350,000 for the unnamed family, she said.

--

thomas.maugh@latimes.com

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