Women of Latin American descent, particularly those with indigenous ancestry, may carry a genetic variant that protects them from breast cancer.

Previous epidemiological studies have shown that Latinas seem to be less susceptible to developing breast cancer than women of other ethnicities. Now an international group of scientists, led by UCSF researchers, have identified the spot on the DNA sequence responsible for that protective effect.

The research is still a long way from making testing for the variant available. Scientists still have a lot more work to do to figure out what the variant means and exactly how it interacts with the body to reduce breast cancer risk.

Its good news in a very general sense. But ... I dont think anyone should stop mammograms because of the variant, said Laura Nejerman, lead author of the study published earlier this week and assistant professor of medicine at UCSF. Now what we are trying to do is think of how best to incorporate this genetic information with other risk-factor information to better provide a picture of breast cancer risk.

But the discovery highlights the existence of genetic risk factor differences between racial groups and ethnicities, and the advent of genome decoding allows researchers to explore those differences. Understanding these variations could shed light on who is most at risk for breast cancer and why some people are less likely to develop the disease and knowing those could lead to a better understanding of cancer overall.

White women of European descent have about a 13 percent lifetime risk of breast cancer, according to National Cancer Institute data from 2007 to 2009. For African American women the risk is about 11 percent; for Asians and Pacific Islanders the risk is about 10 percent.

For Latinas, the risk is 9.8 percent, but its even lower in the 7 percent range among those with indigenous American ancestry, including those from Alaska.

The researchers initially focused on trying to figure out whether there was a genetic variant in European populations that put them at higher risk. Research has identified various mutations, particularly the BRCA genes most closely associated with those of European Jewish descent, that put certain people at higher risk of breast cancer. But their work eventually led them to discover the protective variant in Native American and Latina populations.

Significant impact

Theres no question this is the real thing, said Dr. Elad Ziv, professor of medicine at UCSF and senior author of the study, which was published this week in the journal Nature Communications.

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Genetic variant helps protect Latinas from breast cancer