Huge genetic-screening effort helps pinpoint roots of breast cancer

By Heidi Ledford

A massive study of nearly 4,000 variants in a gene associated with cancer could help to pinpoint people at risk for breast or ovarian tumours.

The information is sorely needed: millions of people have had their BRCA1 gene sequenced. Some variations in the DNA sequence of BRCA1 are linked to breast and ovarian cancer; others are thought to be safe. But the effects of most variants are unknown, leaving patients and physicians alike at a loss to interpret the results.

The study, published on 12 September in Nature1, examined the effects of thousands of such variants on the survival of cells grown in the laboratory. The findings could help physicians to interpret the mutations’ significance. For example, a variant that hampers a cell’s ability to repair DNA in the lab might also be linked to cancer in the clinic.

“Every patient is different. Every physician is different,” says Jay Shendure, a geneticist at the Brotman Baty Institute for Precision Medicine in Seattle, Washington, and a co-author of the study. “But if such a variant were present in a family member of mine, would I use this information? Absolutely. Otherwise, there’s no information.”

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