Seeking A Godlike Power

By LEON JAROFF

Staring at the walls of doctors' offices while awaiting their turn, 21st century Americans may see a colorful chart hanging next to the traditional diplomas and the renderings of skeletal parts and organs. It will depict the 23 pairs of human chromosomes and pinpoint on each one the location of genes that can predispose people to serious disease.

By then, scientists involved in the $3 billion Human Genome Project will have isolated and identified most or all of the more than 100,000 genes crammed into the human genome, the strand of DNA in the nucleus of each of the body's 100 trillion cells (with the exception of red blood cells, which have no nuclei). And scientists will have sequenced, or placed in order, the 3 billion chemical code letters in that strand, giving them the ability to read nature's complete blueprint for creating a human being. As the project nears completion in the first decade of the next century, knowledge flowing from it will begin to have a major impact on medicine and other sciences, industry, agriculture, law and the environment. The stage will be set for an Age of Genetics that could rival the Industrial Revolution in its impact on society.

In 15 or 20 years, predicts biologist Leroy Hood of the California Institute of Technology, doctors will be able to take a blood sample from a newborn infant, extract DNA from the blood and insert it into a machine that will analyze 100 or so genes. "That will give us DNA fingerprints of genes that predispose us to common kinds of diseases," Hood says. Based on the genetic profile, the computer will dispense some medical advice. It might say, "This individual has a tendency toward skin cancer and should avoid overexposure to the sun." Or: "He has insufficient LDL cholesterol receptors and a proclivity to obesity, so he should begin a high-fiber, low-fat diet at age 3." Explains Mark Skolnick, a geneticist at the University of Utah: "Once you can make a profile of a person's genetic predisposition to disease, medicine will finally become largely predictive and preventive." With the profusion of such profiles will come a demand for, and laws enforcing, genetic privacy, to ensure that those with potentially crippling or lethal genes are not discriminated against by employers or insurers.

Other contentious issues will arise. Doctors will be able to detect many serious genetic diseases at the fetal stage, which will lead some parents to opt for abortion. But there will also be preventive measures for people who want to avoid passing their defective genes on to their children. When one parent carries the deadly and dominant gene for Huntington's chorea, for example, there is a 50% chance that any offspring will have it too. To reduce those odds to zero, doctors of the future will extract several eggs from the prospective mother and fertilize them in a test tube with her husband's sperm. When the fertilized eggs have grown to the 32- or 64-cell stage, the doctors will flick off a few cells from each and analyze their DNA. When they find an egg carrying a gene without the fatal defect, they will implant it in the uterus and allow the fetus to grow to term, free from the threat of Huntington's disease.

For those who do inherit a deadly gene or two, research will provide drugs to alleviate the symptoms. The active ingredient in these drugs will be & protein mass-produced by bacteria or by plants. In each case, healthy versions of the genes that have gone awry in humans will be inserted into the DNA of the producer. In the next several decades, the drug treatment will be supplemented or replaced by genetic engineering. Doctors will insert good genes into a patient's DNA, where they will take over the function of defective ones and actually cure the disorder. "The gene then codes for the production of the missing protein," explains University of Michigan geneticist Francis Collins, "and the protein is the drug. What you're delivering is the instructions instead of the product."

Meanwhile, as public fears about genetic engineering fade, agricultural scientists will be producing new and revolutionary plants. They have already inserted a variety of plant, animal and human genes into potato and tobacco plants, transporting the genes to their target in a bit of DNA from a bacterium that naturally infects plant cells. These hybrid plants now produce small quantities of natural polymers and chemicals for industrial purposes, proteins for medical use and enzymes for food processing. In the next few decades, they will become factories of mass production.

The next century will bring hundreds of genetically engineered foods: disease-resistant fruits and vegetables with longer shelf life, starchier potatoes, beans with more protein. "We will come up with new varieties of low-fat, high-fiber foods that taste good and that people really want to eat," says Charles Cantor, principal scientist for the Energy Department's branch of the genome project. Plant genetics will also help the environment. Scientists envision placing genetically engineered plants on either side of expressways to extract lead and nitrous oxides from the air. Plants designed to absorb more carbon dioxide could help stem the advance of the greenhouse effect.

All told, genetic technology will give humankind an almost godlike power to improve its condition. It will be one of society's major tasks in the 21st century to develop a moral and ethical code to match, and help control, this awesome ability.