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The shape of the future
Sunday, June 25, 2000
What is the Human Genome Project?
This is the international effort to find the location of every human gene -- a process called gene mapping -- and to determine the spelling of the genetic code, the sequence of chemical letters in the DNA molecules that comprise our chromosomes. It formally began in 1990 and is scheduled to finish by 2003. In the United States, the project is run by the U.S. Department of Energy's Human Genome Program and the National Institutes of Health's National Human Genome Research Institute.
I've heard of genes, but what is a genome?
A genome is a complete set of genes and other genetic material. In humans, every cell with a nucleus carries a complement of 23 pairs of chromosomes, which are made of DNA and contain all of the human genes.
What do you mean by "other genetic material?"
Chromosomes are made of DNA, a long, chain-like molecule. Genetic information is encoded by a sequence of four chemical "letters" in the DNA chain. But genes account for only about 3 percent of the DNA in our cells. No one is sure what, if anything, the rest of our DNA does. This "extra" DNA is sometimes called junk DNA.
How big is the genome?
The DNA in each cell contains about 3 billion letters -- enough to fill 200 Manhattan telephone directories (each with 1,000 pages). It would take you 91/2 years to read it out loud, assuming you could read 10 letters per second and read nonstop.
What is the rough draft of the human genome that we've heard about?
Both the Human Genome Project and a private firm, Celera Genomics of Rockville, Md., are sequencing the human genome. The public consortium had promised to have a rough draft ready by this month. But now the consortium and Celera reportedly have reached an agreement to combine their efforts. An announcement is expected this week. The sequence is expected to be more than 3 billion letters long and initially will have gaps of varying sizes every 10,000 letters or so. Those areas, missed by the assembly-line methods used for sequencing so far, will be filled in by other methods later.
What will mapping and sequencing the human genome accomplish?
Detailed information about our DNA will provide important new clues about how people evolved, how genes work and interact, and what differentiates people from each other. From a medical standpoint, it should help reveal the genetic underpinnings of most diseases, leading to new diagnostic tests, new strategies for preventing disease and new therapies. Changes in gene expression may be used to identify infectious agents. Genes might be manipulated to produce natural proteins that can be used as pharmaceuticals, or genetic insights might be used to develop drugs that are more effective or have fewer side effects.
How long will this take?
It might take another century before biologists have figured out most of the genome's secrets. New genetic tests for diseases are becoming available all the time, but it will take years to develop new therapies for those diseases. Most authorities say it will be another decade before genetics transforms medical practice.
How many human genes are there?
Scientists have discovered 6,000 to 7,000 human genes, but no one is sure yet what the total is. A decade ago, estimates ranged from 50,000 to 100,000, but the discrepancy in estimates has only grown larger as researchers have learned more details about the human genome. Some biotech companies say they have evidence for as many as 140,000 genes; recently, academics at the University of Washington suggested the real number is closer to 34,000. Some say there are as few as 28,000.
How much does our DNA weigh?
All of the DNA in all of our cells equals about 1 percent of our body weight. A 160-pound man, for instance, carries around 25 ounces of DNA.
Who else is involved in the Human Genome Project?
Eighteen countries, including Canada, China, Russia, Germany, France, Japan and the United Kingdom, have human genome programs. The Human Genome Organization provides international coordination of these efforts.
Who is doing the sequencing work?
Five centers are doing the bulk of the sequencing work. Three are sponsored by the NIH: The Whitehead Institute/MIT Center for Genome Research in Cambridge, Mass.; Baylor College of Medicine in Houston, Texas; and the Washington University Genome Sequencing Center in St. Louis. The DOE's Joint Genome Institute combines efforts at the Los Alamos, Lawrence Livermore and Lawrence Berkeley national laboratories. A fifth major center is the Sanger Center in Cambridge, England. Another 11 centers around the world also contribute to the sequencing effort.
Whose DNA is being sequenced?
No one knows exactly whose DNA is being studied. Several volunteers contributed cell samples to a researcher in Buffalo, N.Y., but no one knows which ones ultimately were used for sequencing. The final reference sequence will be compiled from several individuals. From a genetic standpoint, we're all pretty much the same -- on average, individuals differ by only one letter for every 10,000 letters in the genome.
How much does all this cost?
The NIH and DOE expect to spend $2.8 billion by the time the project is complete in 2003. The cost of sequencing alone will total about $250 million.
Who does medical genetic research?
Among academic institutions, Washington University and Baylor College of Medicine, both homes to genome sequencing centers, ranked one and two last year in funding from the National Institutes of Health for genetic programs, receiving $45 million and $37 million, respectively. Rounding out the top five were Stanford University, Case Western Reserve University and the University of Pittsburgh. Pitt received $11 million from the NIH for genetics research.
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