Months into one of the most ambitious scientific undertakings ever -- a 15-year project to create a "map" identifying all human genes -- scientists leading the effort already are urging safeguards to try to prevent their work from being used to discriminate against the people they are intending to help.
Hundreds of scientists around the world are feeding bits of information into a database at the Johns Hopkins University in a project expected to cost $3 billion -- twice the cost of the Hubble Space Telescope.
When finished, scientists hope to have identified genes responsible for everything from hair color and height to inherited diseases, increased risk for other common diseases and even personality traits.
Once the human genetic code is revealed, scientists may then be able to provide genetic snapshots of individuals' risk for an extensive array of diseases through simple medical procedures such as blood tests.
The ultimate scientific goal of the gene-mapping project is to better understand what role genes play in causing disease; to detect the diseases earlier, intervene and treat them more effectively; and to develop strategies for prevention.
But with all its potential for revolutionizing medical care, warnings are being sounded that any new ability to examine the genetic content of the very "brain" of the cell -- its nucleus, where genes reside -- will open the door for harm as well as good. In an unusual moment in the development of science, the very researchers leading this major exploration are also raising questions about ethical implications and alerting the public to its potential for discrimination.
Who besides you and your doctor should be able to find out what your genetic tests reveal?
If employers and insurers know what array of genes an applicant has, will they try to screen out people harboring genes associated with expensive diseases?
As genes for psychological traits become known, would applications of potentially undesirable workers be weeded out?
In the 21st century, will employers and insurers have red-ink stamps that label an application "troublemaker," "dangerous" or "expensive disease risk"?
From the first, James Watson, co-discoverer of the structure of DNA and director of the mapping project, promised to spend 3 percent of the map's budget on reviewing the ethical and social impact the gene map could have.
Last month a joint subcommittee of scientists overseeing the map unanimously passed a motion intended to create a federal regulation that would prevent employers from refusing a job to someone they discover has a high genetic disease risk.
The scientists asked the Equal Employment Opportunity Commission to amend proposed regulations to a landmark disabilities law that took effect in 1990. The amendment would limit post-offer employment entrance medical examinations to assessing job-related physical and mental conditions.
"This is quite important," said Nancy S. Wexler, president of the Hereditary Disease Foundation and associate professor of neurology and psychiatry at Columbia Presbyterian Medical Center in New York.
"You can see an economic reason why employers would want to screen out people with potential disabilities."
An employer is not allowed to use non-job-related medical information to discriminate against an employee, said Dr. Wexler, who chairs the Joint Working Group on Ethical, Legal and Social Implications of Human Genome Research.
Yet employers are allowed to require job applicants who have been given an initial job offer to take full medical exams.
An employer could discover through information from medical tests that the job applicant is carrying genes that put him or his offspring at increased risk of an expensive illness and decide not to hire him -- but hide the real reason for rejecting him, Dr. Wexler suggested.
"What is going to happen if all these predispositions and latent genes waiting to knock us over the head are known to the insurance industry?" asks Dr. Victor A. McKusick, of Johns Hopkins Hospital, one of the world's pioneers in medical genetics. "I think there's a real problem there."
The insurance industry is aware of the debate but not prepared to say what its interest will be in getting genetic information about applicants.
Robert Davies, vice president and chief medical director of Nationwide Insurance Co. in Columbus, Ohio, says, "Overall, the insurance industry should look at genetic information in the same way they look at any other medical information."
However, even if one day technology can produce a wide-ranging genetic profile of an individual, insurers may find it too expensive to require routine testing of job applicants, Dr. Davies said. "We're not even considering it yet," he said.
Donald White, spokesman for the Health Insurance Association of America, which represents 300 commercial health insurers, suggests that the gene-mapping project may have little effect on most people's ability to get health insurance.