Colon Cancer Gene Traced to Arrival in United States

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Colon Cancer Gene Traced to Arrival in United States

By Gardner, HealthDay Reporter

WEDNESDAY, Jan. 2 (HealthDay News) -- Mr. and Mrs. Fry sailed

from the Old World to the New World around 1630 on a ship most likely

named the & .

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.

The MSH2 mutation was brought to Pennsylvania by a German immigrant

couple in the early 18th century.

Neklason and her colleagues arrived at their discovery by studying two

large families, one in Utah and one in New York, that carry the ACP

mutation. The Utah family has more than 7,000 descendants in nine

generations.

The researchers relied on family reports, the Utah Population

Database, records maintained by the Church of Jesus Christ of

Latter-day Saints (Mormons), as well as statewide cancer records in

Utah and Idaho and Utah death certificates and birth certificates.

Family members underwent genetic analysis and colonoscopy data was

available on 120 individuals within these families.

Both families were linked to the Fry family.

Because the couple came here so long ago, many more people than

originally thought may carry the mutation. The researchers have

identified 14 additional families in the United States who have the

exact same mutation.

" They are almost certainly related. They all come off of this founder

somewhere, but we don't know where, and we only have a glimpse, "

Neklason said. " We hope with this publication we're going to be able

to find many families throughout the country that have the genetic

change. "

Current guidelines for detection of people with this mutation are

murky and, Neklason estimated, may detect only about 87 percent of

these people.

However, individuals can help their own cause.

" This stresses the importance of knowing your family history and your

immediate family history, " Neklason said. " The other big implication

is that it's preventable, and that's the important part. "

Current screening methods can detect precancerous polyps and remove

them before they turn malignant.

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