New breast cancer gene raises risk in Europeans

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) – Researchers have found another
breast cancer gene that can greatly raise the risk of the
disease in women of European heritage, according to a report
published on Monday.

They said the gene worked in tandem with the well-known
BRCA1 and BRCA2 genes to raise the risk of breast cancer by as
much as 80 percent.

The team, at Iceland’s Decode Genetics, said their findings
suggest women with certain mutations in two of the genes have
an almost certain risk of breast cancer.

The new gene is called BARD1, Decode’s team reports in the
online journal Public Library of Science Medicine.

“The BARD1 variant works together with the BRCA2 mutation
in Iceland and increases the likelihood of breast cancer from
45 percent in those who have only the BRCA2 mutation up toward
100 percent in those who also have the BARD1 variant,” Decode
chief executive Kari Stefansson said in a statement.

And women with the BARD1 variant who develop breast cancer
are more likely to have tumors in both breasts, Stefansson
said.

Breast cancer is known to run in families and has a genetic
component, although most cases occur in people with no family
history of the disease. Several genes are known to be involved,
including the BRCA1 and BRCA2 genes, p53 and others.

The known BRCA1 and BRCA2 mutations only account for about
3 percent of all cases of the disease.

The Decode team is trying to find other genes that work
with these genes.

They found 1,090 women in Iceland who had breast cancer,
and compared them to 703 Icelandic women who did not. The
company has a database carrying the genetic profiles of
virtually everyone in Iceland.

A certain BARD1 mutation was found in 5.4 percent of breast
cancer patients and 3.1 percent of women who did not have
breast cancer — an 80 percent increase in risk, the
researchers said.

Simply having the BARD1 mutation was not especially
dangerous to a woman, but women who had it and a specific
mutation on BRCA2 had a “dramatic” risk of breast cancer, the
researchers found.

It may be worth developing a test for that particular
combination, the researchers and the company said.

This BARD1 mutation has been found in Italian and Finnish
families with a history of breast and ovarian cancer.

It has not been found in people of Chinese, Japanese,
African-American and Yoruban descent, the researchers added.

“Therefore, the variant may be restricted to individuals
with European ancestry and could contribute to the higher load
of breast cancer seen in this group. However, other BARD1
variants have been discovered in African-American and Japanese
individuals. The contribution of these variants to the risk of
disease is still uncertain,” they wrote.

Breast cancer is the second leading cause of cancer deaths
among women after lung cancer, affecting 1.2 million women
globally and killing more than 400,000 every year, according to
the International Agency for Research on Cancer .