BOSTON — Boston.--So this is what we have been waiting for.
When the first ''disease genes'' were identified and a few people had to decide if they wanted to know whether they were doomed by their DNA, ethicists would shake their heads and say, ''If you think these are tough issues, just wait till they find the breast-cancer gene.''
When it was first clear that genetic tests could enable employers and insurers to screen for inherited, truly pre-existing, conditions, someone would say, ''Just wait till they find the breast-cancer gene.''
When parents faced the dilemma of whether to bring children into the world as genetic heirs to rare illnesses, someone would say, ''Just wait till they find the breast-cancer gene.''
Now the waiting is over. Last week a group of researchers at the University of Utah triumphantly proclaimed victory in the race to identify a genetic marker for an inherited form of breast cancer. And all the questions are coming due.
Scientists on earlier voyages over the vast new sea of genetic knowledge had discovered small islands of illness like Huntington's and cystic fibrosis. But these geneticists have discovered the mainland: breast cancer.
There is no one so isolated in this land that he or she doesn't know a woman with this disease. One out of every nine American women will contract it in her lifetime. Some 182,000 are diagnosed with breast cancer each year and 46,000 die of it. Only 10 percent of these cancers are thought to be inherited. Only 5 percent are caused by the newly discovered gene BRCA1 and a small percentage more by BRCA2. It will take a year or two before there is a way to test for it.
But as of today, the hopes, the traumas and the uncertainties raised by genetic knowledge are no longer limited to exotic diseases. They are becoming part of our everyday, garden-variety lives.
For the ''breast-cancer families,'' this new knowledge will present a series of decisions. These are families that have been devastated by breast cancer, families that have lost mothers, aunts, sisters and cousins. Many women in these families wait for cancer as if it were inevitable. Others have healthy breasts removed with more relief than loss.
Some may find themselves free of the cancer gene and the cancer fear -- though that reassurance is shaky when nine out of 10 cases of breast cancer are not inherited. But those who carry the gene will find that the future is still uncertain and the options are by no means easy to assess.
It's believed that 85 percent of those with the gene will get breast cancer by the time they turn 65. But these odds do not come with a precise timetable that says who will be struck at 31 and who at 64. Nor is there certainty about which cases will be fatal and which will be treatable.
Knowing what's in our genes may not say what's in store for us, let alone what to do about it. What should a 24-year-old with an 85 percent chance of getting breast cancer do? Get a double mastectomy? Go on the drug tamoxifen? Have more frequent mammograms? Or fewer?
And by the way, when should a female in a high-risk family be tested? At 30, 17, 8, or in the womb? Is breast cancer such a dread disease that some parents would chose to abort a fetus with the gene? Will the men and women who carry this gene consider themselves too genetically flawed to reproduce? Will they blame themselves for the cancer of their children?
As if those questions weren't unsettling enough, when we have a test for the breast-cancer gene, we will have to decide who gets tested. Anyone whose grandmother or niece had the disease? Anyone who asks for it? Anyone who can pay for it?
In time scientists will devise a genetic test for every disease. There will be a lag between what we can know and what we can do about it. Meanwhile, as ethicist Adrienne Asch of Wellesley College asks, ''How much of an advance is it when the diagnosis is so far ahead of the treatment?''
I don't mean to mute the applause for these intrepid discoverers. They are scientific Magellans still at the beginning of a voyage that will map the whole human genome. The profound hope is that knowing will lead to healing.
But today we have an answer to a scientific puzzle that comes with a hundred new questions. Just wait until they find the breast-cancer gene. Now we wait for the cure.
Ellen Goodman is a syndicated columnist.