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What Does It Mean?: Sep 24, 2014

The results of some gene tests bring more uncertainty than was present before testing, the New York Times writes. It highlights the cases of a few patients who underwent testing for one disease, but found out they had a variant — often linked to another disease — whose significance is hard to interpret.

For instance, Jennifer, whose last name the Times doesn't disclose to protect her privacy, has a family history of breast cancer, and she decided to undergo genetic testing to see if she was at risk for the disease. When she was offered a test that included some 20 other genes linked to cancer, she agreed, the Times says, thinking that more information was better.

While Jennifer found out that she didn't have breast cancer-related mutations, she did have a variant linked to stomach cancer. In people with family history of that cancer, the Times says, patients are often urged to have their stomachs removed — that's how serious the variant is taken. But in people without family history of the disease like Jennifer, there's uncertainty as to what carrying the variant means.

Some gene panel tests include genes "because they could be tested, not necessarily because they should be," Kenneth Offit from Memorial Sloan Kettering Cancer Center tells the New York Times.

As the Times also notes, as more people undergo genetic testing, the proportion of variants that have unknown significance will fall. For example, it says that when Myriad Genetics began testing BRCA1 and BRCA2 genes for breast cancer-related mutations, some 40 percent of the variants it found were of unknown significance, but that percentage has now dropped to 2 percent.

Additionally, there are ongoing projects to catalog variants of unknown significance, including the Prompt, for Prospective Registry of Multiplex Testing database developed by Memorial Sloan Kettering, the University of Pennsylvania, the Mayo Clinic, and the Dana-Farber Cancer Institute. And Jennifer tells the Times that she wants to join the project so that her mutation could be better understood, for her children's sake.

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