Related CNN stories: Swiss voters reject curbs on genetic engineering - June 7, 1998 Researchers: Gene found for heart failure - April 30, 1998 Lawyer: New DNA tests point to killer in Sheppard case - March 5, 1998

Every week seems to bring another announcement of genetic discovery about one or more diseases, and with each discovery comes the promise of soon to be developed genetic tests. These tests offer information about who is likely to develop cancer or other diseases, and the scientific breakthroughs that make these tests possible are remarkable. But the information offered by such tests offers limited benefit, and may in fact cause more harm than good.

All but a few of the genetic tests now available don't actually predict whether or not a person will contract a disease or condition, but instead offer much more limited information about how much more likely they are to develop a disease compared to someone who tests "normal."

This kind of information is not very useful for individuals, who would like to know whether they actually have or will get a particular disease, and what steps, if any, they ought to take to protect their health. But probabilities are very useful for predicting how many people in a group will contract cancer or Alzheimer's disease, and so insurance companies and potential employers will be very interested in measuring their risks using genetic tests.

The genetic codes that will be used in tests to predict health risks often are first identified by research on particular groups. For example, research on women of Jewish ancestry from Eastern Europe, led to tests that predict increased breast cancer risk in women with the certain genes. This discovery and others like it point to only a few of what are probably many genetic defects that influence the development of diseases such as cancer, and it is only because of the genetic usefulness of members of a population that their "defects" are catalogued first.

But being first is double-edged. Members of the group are the first to gain access to more information about future health risks and to be able to seek early testing and treatment. But they also are the first to have the information used against them -- for instance, to determine eligibility and premiums for insurance or to draw broad conclusions about whether or not they are healthy.

Lastly, one of the promises of genetic technology has been the development of gene therapy: medical techniques that correct the genetic coding that predisposes us to disease. These types of cures now seem as far off as ever, however, considering recent reports that pharmaceutical companies are shying away from developing them. The relatively small number of affected people whose genetic diseases could be cured by gene therapy means there is limited financial incentive to develop them.

Genetic information will grow as a powerful tool to help understand the causes of disease and illness. But in many cases this is power to predict our futures without offering us anything to alter it. Whether or not any of us would like to know what future our genes hold for us, it is up to us to decide whether that information should be collected, and more important, who should be able to see and use it.

Until there are therapies to go along with them, genetic tests should be offered only by highly trained geneticists or genetic counselors, and results should be treated in much the same way as HIV test results-as potentially discriminatory and stigmatizing information.