A primer on the Supreme Court's ruling that human genes can't be patented.
What did the court say?
Patents held by Myriad Genetics Inc. on BRCA1 and BRCA2 genes are not valid, because isolating a naturally occurring segment of DNA cannot be patented. We all have two copies of these genes; mutations in one of them can give a woman up to an 87 percent risk of developing breast cancer and up to a 54 percent risk for ovarian cancer.
How many people have them?
In the United States, about 5 to 10 percent of breast cancers are thought to be due to bad BRCA genes. Among breast cancer patients, BRCA mutations are carried by 5 percent of whites and 12 percent of Eastern European (Ashkenazi) Jews. Rates in other groups aren't as well known.
How expensive are the Myriad tests?
They cost $3,000 to $4,000, and insurers cover them only for women thought to be at high risk because of family history of breast or ovarian cancer or other risk factors. The tests are not recommended for women at average risk.
What about other tests for breast cancer genes?
Some other tests look for mutations in 16 other genes less commonly involved in breast cancer, but those have not been able to include BRCA1 and BRCA2 because of Myriad's patents. Those other tests cost around $2,600. The court's ruling means these tests likely will be able to include BRCA1 and BRCA2 for no or little additional cost, giving a more complete picture of a woman's risk.
What about other gene tests that can still be patented?
The court said tests that involve making cDNA, or complementary DNA, can still be patented.