Cover Story

Cracking the code

Mapping the human DNA sequence is a dream come true for many scientists, but the possible consequences are giving bioethicists nightmares. Meanwhile, some observers think Darwinian assumptions cause researchers to place too much emphasis on genes

Issue: "Cracking the code," April 29, 2000

in Houston - Biology's version of the Book of Life is being written, in part, on the 14th through 16th floors of a gleaming medical tower at Baylor College of Medicine in Houston, Texas. Jeans-clad biotechnicians peer at computer screens, poke with sterilized toothpicks at spot-covered gel in trays, and cart racks of test tubes down gray hallways to and from labs filled with banks of thermo-cyclers, sequencers, and other equipment. Most workers are under 30 and hold "entry-level" positions. Few hold graduate degrees, and some haven't finished college. It seems an unlikely setting for what President Bill Clinton in March called "the scientific breakthrough of the century, perhaps of all time." The technicians are nearly finished "sequencing" the entire human genome; that is, determining the order of the three billion pairs of nucleotides that make up human DNA. The Human Genome Sequencing Center at Baylor is one of five major sequencing centers in the United States, with another in Britain and minor centers scattered around the world. Together they make up the decade-old Human Genome Project, an international consortium directed by the National Institutes of Health (NIH) and the Department of Energy. The $250 million Project plans to release its first draft by summer, having sequenced 90 percent of the genome with 99.9 percent accuracy. The sequence is on a publicly available database, allowing researchers to hunt for all 80,000 to 100,000 genes-sections of DNA that are believed to control cell development and operation-in a typical human cell. Scientists use this genetic map to try to figure out what each gene does and how it works with other genes. They then associate mutations in particular genes with specific diseases. The sequence of human DNA has been called a periodic table of the elements for human biology, or as a recent Newsweek story gushed, the "blueprint of human life, the code of codes, the holy grail, ... what it means to be human." Many believe that this project will revolutionize modern medicine. The media are jumping on the bandwagon; all the attention over the last few years has sent biotech stocks soaring. The final version, expected two years ahead of schedule in 2003, will be, according to NIH National Human Genome Research Institute director Francis Collins, a professing Christian, a "phenomenally significant event in human history." Perhaps. Enthusiasts predict that in a few more decades genetic research stimulated by the Human Genome Project will lead to cures and more effective treatments for diseases ranging from cancer to schizophrenia. Involvement in the Human Genome Project "is a work of discovery which can also be a form of worship," wrote Dr. Collins in 1997. "It is part of our mandate as Christians to pursue such medical advances, attempting to emulate Christ in his healing role," he said. In 30 years, predicts Dr. Collins, genetic technology will be so advanced that your physical exam will include a complete genetic profiling. The doctor will swab a few cells from inside your cheek and insert them into an analyzer. A computer will compare your genome to the thousands of disease genes identified by then, pin-pointing the illnesses you already have or may develop. Perhaps. Doctors will also use genetic technology to prescribe preventative measures, like specialized diets for those at increased risk of heart disease and regular screening for those with a genetic predisposition for colon cancer. Some presently incurable diseases will be defeated with "gene therapy," the technique of using viruses to insert healthy genes into cells with defective genes. Eventually, goes the claim, once scientists understand how particular genes cause diseases, they will design drugs accordingly, instead of using the current trial-and-error method. Scientists will know why some drugs and therapies work so well for some patients but put others in the hospital. Doctors will prescribe medications with the least unpleasant side effects for a given patient. Some scientists predict designer babies-or at least the ability to influence hereditary traits like height and intelligence and eye color. In addition, genetic science will produce a host of industrial and agricultural breakthroughs, like toxin-eating bacteria and more pest-resistant crops. That's the optimistic assessment of the impact of genetic science. But Celeste Condit, a communications professor at the University of Georgia who writes regularly on ethics and genetics, offers a nightmare scenario that includes:

  • routine prenatal genetic screening, with stringent standards for determining which babies live and die;
  • the ready availability of genetic testing generating a sort of public hypochondria, with fears of disease far exceeding the actual risks;
  • genetic discrimination, with jobs and health insurance denied to those at risk of serious disease;
  • the sorting of young children into career tracks and social classes based on their "genetic potential."

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