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Genome the crowning achievement of medicine in 2000
WASHINGTON (CNN) -- By all accounts the year 2000 was a milestone for the field of medicine. And nowhere was that seen more than in the study of our genes, known as the human genome.
In a White House ceremony in June, the men who led the efforts to map the human genome announced they had completed working drafts of the 3.1-billion letters that make up the instruction book of who we are.
Dr. Francis Collins, who heads the public effort known as the Human Genome Project, and Craig Venter, president of the private counterpart Celera Genomics, agree the potential this project gives us for making better medicine is tremendous.
"The year 2000 is gonna be a bright line in the history of both science and medicine," Venter said, " because it's the start of a new era."
The mapping is not quite complete. The majority of the DNA is sequenced, but now scientists have to figure out what those genes do.
"What is their function, what do their instructions mean. How do those determine a human being in a biological sense," Collins explained, "and how do glitches in those instructions result in disease."
Venter's company has mapped the genome of the mouse to help in this undertaking. Scientists can compare parts of the human genome to the mouse and see where the differences lie. One surprise is how similar we are to mice; of the 30,000 genes, only a few hundred are different.
Another surprise is how few genes humans actually have.
"Groups have been saying there's 100,000 or 140,000 genes, but there's only 30- to 35,000 genes in the genome." Venter said.
Both projects will start telling us what they've learned so far from the genome early in 2001. It's this type of information that will lead to better and more precise medicine.
Genome science has already produced gene therapy, a technique that attempts to actually replace or fix damaged genes. Although experiments have been underway for about 10 years now, the therapy isn't progressing quite as fast as experts thought it would.
There were four major successes in the field in the year 2000: against a severe combined immune deficiency syndrome, often referred to as the bubble boy disease; in the treatment of head and neck cancer; for patients with failing hearts; and against hemophilia.
But the field of gene therapy spent much of 2000 recovering from its lowest point -- the death in 1999 of 18-year-old Jesse Gelsinger during a gene therapy trial for a rare liver disorder.
Many gene therapy trials were put on hold after Gelsinger's death while the U.S. Food and Drug Administration developed stronger oversight of such experiments. Trials are resuming as the new regulations are being implemented.
Despite the problems, "almost everyone still believes that gene therapy will still revolutionize the practice of medicine," said Dr. French Anderson, who conducted the first gene therapy experiment 10 years ago.
Another approach set to benefit from the human genome project is gene-based medicine. Instead of replacing bad genes, this method works on the proteins that are produced by genes and determine the action of the gene.
Gene-based medicine blocks bad proteins or mimics good ones.
"You understand how the gene works," Collins says, "you understand how it's misspelling results in the risk of disease, and then you develop a molecule, a small molecule, a drug molecule that tweaks the system just right to compensate for that."
One example of gene-based medicine is the drug STI 571, which is showing promise against one type of adult leukemia in a clinical study.
In this disease, two chromosomes are rearranged, putting two genes next to each other that don't belong side-by-side. When those genes are fused together they produce an abnormal protein which causes the cancer.
STI 571 simply deactivates the abnormal protein.
The majority of patients in clinical trials with this drug are in sustained remission. Before this drug, they didn't respond to standard therapy.
Dr. Brian Drucker, who helped develop STI 571, says this is the medicine of the future. "With the identification of all the genes through the genome project, we'll much more rapidly be able to translate from the understanding of the genetic bases in the disorder to specific therapy."
Another example of gene based medicine is a drug called Keratinocyte Growth Factor - 2 (KGF-2). It was created by the company Human Genome Sciences and is considered a therapeutic protein because it mimics a positive action of a gene. Researchers copied the natural triggers that cause the body to release certain growth factors involved in wound healing. The drug is currently in clinical trials for treating chronic wounds and for helping to reduce the side effects of chemotherapy.
To be sure, no one believes that genes control everything; interaction with the environment also plays a key role. But genes are the basis for how we handle the environment.
Says Anderson, "If we understand our genes and understand what genes are turned on and turned off in order to allow us to breath, to eat, to move, we'll be a long way toward understanding how to develop attacks for diseases."
But with every scientific advance comes ethical questions. The human genome is no exception.
Although we are able to diagnose more diseases through genetic testing or predict who is more likely to get them, we still can't cure a lot of them. While there is still no broad federal law to protect the privacy of genetic information, some U.S. states and counties have enacted provisions to guard the information, and President Clinton issued an executive order in February barring genetic discrimination among federal employees.
Supporters of privacy protections say knowing who is at risk for depression, Alzheimer's disease, or cancer, for example, could open the door to genetic discrimination.
"These sorts of predictions could be used, if you will, to take away people's ability to get life insurance, health insurance, disability insurance, and even a job," said Dr. Arthur Caplan, a leading medical ethicist at the University of Pennsylvania.
Venter and Collins both have called on Congress to pass laws banning genetic discrimination, but none of the six bills introduced on Capitol Hill in 2000 to do this was ever passed.
But science isn't waiting.
"In roughly two decades," said Collins, "I think you will see those kinds of drugs basically entering the mainstream for basically all diseases you can think of."
Venter agreed. "It's the equivalent of going into a darkened room and turning on the light and all of a sudden seeing the foundation of the whole future."
The genetic accomplishments of 2000 are just the beginning.
Gene research yields drug that helps heal chronic ulcers, company announces
National Human Genome Research Institute (NHGRI)
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