By Will Dunham

WASHINGTON, April 27 (Reuters) - Americans may be much more willing to get genetic tests showing predisposition to diseases with this week's expected final passage by Congress of a bill barring discrimination based on one's genetics, experts say.

Genetic testing, typically involving a sample of blood, saliva or tissue, can help indicate whether a person has inherited a tendency to develop certain diseases -- for example breast, ovarian or colon cancer or Huntington's disease.

"Many people have been getting a genetic test using an assumed name because they were afraid that the information would otherwise haunt them," Dr. Francis Collins, head of the National Human Genome Research Institute, part of the U.S. government's National Institutes of Health, said in a telephone interview.

"And they've sometimes asked their physicians to lie about whether the test was positive in order to protect them."

The bipartisan bill would bar health insurers from turning down coverage or raising premiums for healthy people based on their genetic predisposition to develop a disease.

It also would prohibit employers, unions and employment agencies from using personal or familial genetic information in hiring, firing, compensation or promotion decisions.

"When this bill passes, we'll have protections to be able to tell people you don't need to worry about insurance or employment discrimination," Kathy Hudson, director of the Washington-based Genetics and Public Policy Center at Johns Hopkins University, said in a telephone interview.

The bill, supported by the White House, is expected to go before the House of Representatives this week for final approval before heading to President George W. Bush to sign into law. The Senate passed it on Thursday.

CONFIRMING SUSPICIONS

Doctors may order genetic tests for various reasons, including looking for gene-based diseases in adults before symptoms appear or confirming a diagnosis in someone with symptoms.

Tests also may find whether a person has a genetic predisposition to a disease that could pass to children.

Hundreds of such tests are available. The results can prompt important medical decisions.

For example, women shown with a mutation in BRCA1 or BRCA2 genes associated with breast cancer have a 40 to 85 percent chance of developing the disease by age 70. Faced with those odds, some women have opted to undergo mastectomies to remove both breasts before any sign of disease.

A number of companies market various tests directly to the public, typically costing hundreds of dollars.

Last year, two companies -- Iceland's Decode Genetics Inc <DCGN.O> and 23andMe, a U.S. firm funded by Google Inc <GOOG.O> -- launched rival services offering people a glimpse of their entire genomes for just under $1,000. Another unlisted U.S. company, Navigenics, has since joined the field.

Some medical experts say the services can be a waste of money and give people little more information than they would know from studying their family medical history, especially as many diseases have complex genetic underpinnings.

Some companies also are drawing government scrutiny.

The California Department of Public Health said last week it was looking into consumer complaints against a handful of unnamed companies offering direct-to-consumer genetic testing. The complaints involved cost and accuracy of tests and whether a licensed doctor ordered them as required. (Editing by Maggie Fox and John O'Callaghan)

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