It's not the genes themselves, but mutations that can put women at higher risk of breast cancer.(Getty Images)
It’s not the genes themselves, but mutations that can put women at higher risk of breast cancer.(Getty Images)

On Monday, the U.S. Supreme Court will hear oral arguments in a case that asks a central question: Can you patent a human gene?

Are genes naturally occurring and therefore not patentable by law? Or, since DNA must be extracted and processed to be read, is it no longer a natural product and so indeed can be patented, as human genes have been for 30 years?

Over at KQED Science, reporter Lauren Sommer has a great breakdown of the issues in this case — not only the ethical questions but also the business angle, so critical to the Bay Area’s thriving biotechnology industry.

But let’s take a step back and look at the genes at the heart of the case, BRCA1 and BRCA2. According to the National Cancer Institute, these genes help keep cells’ genetic material in order. They handle what’s called tumor suppression.

Everyone has these genes — women and men alike — but the question is whether you have a mutation in one or both of these genes that inhibits the tumor suppression function. With impaired tumor suppression, you’re at higher risk for cancer. Women with certain types of BRCA mutations are five times more likely to develop breast cancer and at least 10 times more likely to develop ovarian cancer. Both women and men with these mutations are also at increased risk for other cancers, including pancreatic cancer, prostate cancer and melanoma.

Dr. Robert Nussbaum is a medical geneticist at UCSF. He stresses these are fairly rare mutations, accounting for perhaps 5 percent of all breast cancers. The BRCA gene, like other genes, can mutate in many ways, but not all those mutations are harmful.

In a genetic test, analysts are “looking for misspellings, like a spellcheck,” of the cell’s DNA, he said. And that misspelling might not mean anything. It could be just a “common variation” such as having brown eyes or blue eyes. Or it could be a change “which is actually going to affect the function of that protein and result in someone having a markedly increased risk for cancer,” he added.

In genetic analysis, the gene is compared with a catalog of thousands — or hundreds of thousands — of other people who had the test to determine if the mutation is positive, negative or ambiguous. The NCI cited a study that found 10 percent of women who had the BRCA 1 or 2 test were in this “ambiguous” category, then added:

Because everyone has genetic differences that are not associated with an increased risk of disease, it is sometimes not known whether a specific DNA change affects a person’s risk of developing cancer. As more research is conducted and more people are tested for BRCA1 or BRCA2 changes, scientists will learn more about these changes and cancer risk.

But even if a woman has a mutation that puts her at increased risk of cancer, it’s just that: an increased risk. Genes do not determine everything, Nussbaum said. Diet, culture, behavior and environment all play a role in cancer development. The NCI lists different approaches — from more frequent screening tests to prophylactic surgery — that women might consider when receiving a positive result.

Learn More

Listen to Forum: Who Owns Your Genes?

Gene Patent Supreme Court Case Centers Around Two Breast Cancer Genes 18 April,2013Lisa Aliferis


Lisa Aliferis

Lisa Aliferis is the founding editor of KQED’s State of Health blog. Since 2011, she’s been writing and editing stories for the site. Before taking up blogging, she toiled for many years (more than we can count) producing health stories for television, including Dateline NBC and San Francisco’s CBS affiliate, KPIX-TV. She also wrote up a handy guide to the Affordable Care Act, especially for Californians. Her work has been honored for many awards. Most recently she was a finalist for “Best Topical Reporting” from the Online News Association. You can follow her on Twitter: @laliferis

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