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Portuguese Breast Cancer Genes
When it comes to genetic testing for breast cancer, those of Ashkenazi Jewish ancestry have had access to more resources than others. That’s because scientists have pinpointed three specific gene mutations that could predispose them to breast cancer, and have created tests to detect the mutated genes.
Soon, a similar approach could be available for those of Portuguese ancestry, say scientists at the Lisbon Oncology Institute in Portugal. They’ve discovered that some Portuguese people have a specific mutation in the BRCA2 gene—the second breast cancer gene to be discovered. Called a founder mutation, the genetic error originated in one population in a single geographical region, and spread from there.
The discovery is especially important because there are so many people of Portuguese descent around the world who might carry the mutation, says study author and medical oncologist Fatima Vaz. Researchers estimate that the mutation originated between 2,400 and 2,600 years ago, right before Portuguese sailors and traders fanned out into other parts of the world, enabling them to spread the gene to such places as Japan, India, Africa and Brazil. From the 1950s through the 1970s, the Portuguese (and their genes, of course) emigrated to France, Germany, Canada, and the United States.
Vaz, whose study appeared in the Journal of Clinical Oncology in May, notes that the Portuguese mutation (which she calls c.156_157insAlu) differs from those found in Ashkenazi Jews. She recommends that anyone of Portuguese ancestry with a family history of breast cancer be screened specifically for the mutation, but says that may be difficult for now. To make the test widely available, she’s trying to form an international consortium through labs in Paris and Toronto, where large Portuguese communities reside. “There’s a huge concentration of Portuguese in New Jersey and the San Jose, CA, area,” Vaz adds. “We’re trying to make contact with those places as well.”