A new test makes it possible to predict whether people from families with a history of Huntington's disease will get the genetic brain disorder themselves, researchers at Johns Hopkins University report.

"We can now predict who will develop Huntington's disease with 88 percent accuracy," says Dr. Susan E. Folstein.

Folstein and a team of researchers have found the specific piece of DNA, the genetic code, that causes the affliction. And while they haven't found the gene itself, they have found a way to determine if it is present.

Children of Huntington's patients have a 50 percent chance of developing the disease themselves, and then passing it on to their children. Because the disease usually doesn't show up until late adulthood, many such people forgo having children in fear of passing it on.

With the test, the researchers say, these people will be able to know whether they carry the gene while they are still young enough to have children.

The disease has symptoms ranging from physical involuntary movement to severe mental deteriorations.

"Probably sometime next year we will have the first pilot testing program," says Dr. James Gusella, a neurologist at Massachusetts General Hospital, who collaborated in the research. "It would only be after that that it would be generally available."

Approximately 25,000 Americans have Huntington's disease, and more than 100,000 children are considered to be at risk.