In the 1980s, biologists uncovered the genetic causes of such perplexing ailments as cystic fibrosis. In the '90s, they will turn their attention to the genetics of human behavior.
In human genes, the basic units of heredity, scientists may find the roots of such complex disorders as manic-depressive illness and schizophrenia. Unlike simpler ailments studied so far, these are the result of more than one genetic malfunction.It will take more than 10 years to understand "the molecular nature of our emotional life," said Philip Leder, chairman of the genetics department at Harvard Medical School. But understanding of some behavioral disorders should come by the year 2000, he said.
"We know a number of these run in families," he said. "We don't know what genes are involved in that process. They haven't been identified yet. But there is the possibility that with gene mapping we will be able to sort them out."
Gene mapping is the process of sorting through human chromosomes to find the particular genes related to a particular disorder.
Heart disease and cancer, the nation's two leading killers, are also caused in part by multiple genetic abnormalities. They, too, may begin to yield to the rapidly expanding capabilities of geneticists, Leder said.
"There are very few diseases that afflict man or mouse that are not genetic in one way or another," Leder said recently at a gathering of geneticists at the Jackson Laboratory in Bar Harbor, Maine.
By the end of the 1990s, researchers should be closer to a complete, chemical-by-chemical understanding of some of these ailments, said Leder, one of the inventors of the genetically engineered mouse that became, in April 1988, the first animal to be patented.
David Baltimore, a Nobel winnerat the Massachusetts Institute of Technology, shares Leder's optimistic view of the next decade.
"The fast pace of molecular biology shows no sign of slowing down," he wrote recently.
Baltimore said studies of the central nervous system are showing that nerve cells respond to signals in nearly the same way that kidney cells respond to hormones or skin cells respond to growth factors.
"I think this will be a tremendously exciting field in the next 10 years, one that will not only stimulate discoveries in neurology and lead to new treatments for Alzheimer's disease and other degenerative brain diseases but also greatly enrich the fields of psychiatry and psychology," he wrote.
The growing biotechnology industry, where basic research is beginning to be translated into products, has also issued glowing predictions for the 1990s.
The industry's total sales exceeded $2 billion last year. That is expected to climb to $50 billion by the turn of the century, according to an industry survey by the Ernst and Young High Technology Group in New York.
One of the most notable efforts of the coming decade is the so-called Human Genome Project, a $3 billion program to determine the genetic code, or sequence, of all the estimated 50,000 to 100,000 genes that govern human hereditary characteristics. The complete set of genes is called the genome (pronounced JEE-nome).
The project is being coordinated by the National Center for Human Genome Research, part of the National Institutes of Health in Bethesda, Md.
The center's director, James Watson, one of the discoverers of the double helix of DNA, predicts the project can be completed in 10 to 15 years.
That will vastly simplify the process of understanding the function of individual genes and linking certain genes to disease.
Finding disease genes does not immediately lead to a cure for the disease. Researchers must discover how to correct the defective genes - which can be a difficult task. But finding the disease genes is a necessary first step in the process of curing disease.
So-called gene therapy, in which defective genes can be replaced with normal genes, was a goal of genetics during much of the past decade, but it has remained elusive.
Many scientists believe, however, that the first steps toward gene therapy will be taken during the next decade, and some experiments are likely to be at least partly successful.
The leading method will use viruses engineered in the laboratory to insert corrective genes into cells as they infect them. The first trials of the feasibility of this method have just begun at the National Institutes of Health.
Some of the difficult questions biologists will have to answer in the 1990s will be asked outside the laboratory, Leder said.
Recent events suggest that continuing social concerns over animal rights could impede biological research, he said.
In April, for example, demonstrators pounded on windows and broke open a door at the National Institutes of Health, and 37 were arrested. "We're protesting the murders of millions of animals," they said.
In June, the City Council in Cambridge, Mass., home to Harvard and MIT, adopted animal rights legislation that will allow a commissioner to make unannounced lab visits and fine researchers $300 a day for violations.
"There are those who feel the life of a rat is as important as the life of a child," said Leder. "We have to be prepared to make people understand that genetics is another very powerful tool in the armamentarium we have against disease."