Culminating more than a decade of wrangling, the Senate today unanimously passed a landmark bill that would make it illegal for health insurers and employers to discriminate based on genetic predispositions to diseases such as breast cancer.

The Genetic Information Nondiscrimination Act (GINA) now goes to the House, which approved a nearly identical measure last year by a margin of 420 to three, and is expected to vote on this version as early as next week. President Bush has signaled that he will sign it into law when it reaches his desk.

Doctors have access to more than 1,000 genetic tests for diagnosing or assessing the risk of potentially life-threatening diseases, and in recent months the companies deCODE Genetics, Navigenics and 23andMe have begun offering genomewide scans for some of those genes directly to consumers.

Supporters of the legislation say it will encourage Americans to take advantage of such tests by closing gaps in state laws and easing fears that they will be fired or denied health insurance because of them.

Currently, 35 states have laws against genetic discrimination by employers, and 47 bar genetic discrimination by health insurers, according to a 2007 study published in The New England Journal of Medicine.

Under GINA, health insurers would be prohibited from using genetic test results to deny coverage or raise premiums, and employers could not use the information in hiring, firing, setting compensation or promoting an employee. Insurers and employers would also be prohibited from requiring such tests and from collecting genetic information without consent.

The bill does not address discrimination against those already diagnosed with a disease.

The House approved the bill last April, but Sen. Tom Coburn (R–Okla.) stalled Senate voting until this week, citing concerns that employers made be held liable twice for the same violation. On Tuesday, Coburn announced that these issues had been resolved with compromise language.

"We're celebrating the fact that we've been able to take a significant step forward … in addressing the issue of genetic discrimination, which until this point has not been addressed at all," says Kurt Bardella, a spokesperson for bill co-sponsor Sen. Olympia Snowe (R–Me.).

Kathy Hudson, director of the Genetics and Public Policy Center in Washington, D.C., said in a statement that "our challenge now is to make sure that doctors and patients are aware of these new protections."

As fate would have it, tomorrow is National DNA Day, marking the anniversary of the discovery of the double helix by James Watson and Francis Crick.