One of America’s Biggest Genetic Testing Companies Refuses to Publicly Share Data That Could Save Countless Lives

Barbara Zeughauser had lost so many relatives to cancer: Her mother, her uncle, her grandmother, her second cousin. She thought that ghost in the family line might come after her, too. So in 2009, Zeughauser took a test offered by Myriad Genetics. It analyzed her DNA for mutations in the BRCA1 and BRCA2 genes that can make cancer more likely than not, raising the lifetime risk of breast cancer in women to between 55 and 85 percent, and to between 10 and 70 percent for ovarian cancer.

Zeughauser was lucky and unlucky. She got a clear, unambiguous, and accurate answer from the test: She had a bad mutation. But she’d found it before she got cancer. She decided to have her ovaries removed and later had a double mastectomy, reducing her risk to almost average.

Her cousin Ken Deutsch wasn’t so lucky. In 2014, he was hit with bladder cancer. He also went...