BETHESDA, Md. - In today's issue of the journal Science, a team of over 100 scientists from government, university and commercial laboratories around the world reveal a map that pinpoints the locations of over 16,000 genes in human DNA - about one-fifth of the estimated 80,000 genes packaged within the human chromosomes. Constructed largely by scientists at the National Library of Medicine (NLM), research centers supported by the National Center for Human Genome Research (NHGRI), and genome centers in England and France, the map represents the Human Genome Project's (HGP) most extensive effort so far to locate and identify the 80,000 genes in the human genome - the full set of genetic instructions inside a human cell. With it, the number of mapped human genes has tripled in less than two years.
NLM and NHGRI are both components of the National Institutes of Health, the federal government's primary biomedical research facility, located in Bethesda, Maryland.
"This map of human DNA, the literal thread of life, applauds the richness of the human race in several ways," said Vice President Al Gore.
"First, it is an accomplishment attributable to the generosity and cooperation of dedicated researchers around the globe. Second, it will advance our understanding of the genetic basis of baffling diseases that today cause suffering and reduce the quality of life of our family members and fellow citizens. And very importantly, it puts students on the cutting edge of science by providing them with an instantaneous on-line educational tool containing the latest research information about genes and their function in both health and disease," the Vice President said.
"By combining computer technology with biomedical research tools, this map proves the power of a new multi-disciplinary approach to biological science," said NIH Director Harold Varmus, M.D., "and it will make a significant contribution to raising the level of scientific literacy among students.
NLM director Donald A. B. Lindberg, M.D. said, "We are proud of this remarkable voluntary collaboration among several of the world s leading research scientists in molecular biology. The fact that these data are to accessible over the World Wide Web, that is, accessible to millions, means that for the first time, a high school biology student and a university scientist can retrieve data on an equal footing."
Taking full advantage of cutting-edge information technology, an electronic version of the map organizes the details into a readily accessible Internet site with extensive links to supporting data about the DNA structure of the genes and the proteins they encode. In addition, the electronic map is a mouse click away from on-line references in the medical and research literature, which will aid scientists in linking information about a likely disease gene to its role in cell function.
The Internet site will officially be on line at 4:00 p.m. EST, Thursday, October 24.
"A map of this detail gives disease-gene hunters who have narrowed their search to a specific region on a chromosome about a 1 in 5 chance the gene they are looking for has already been characterized by this effort." said NHGRI Director Francis S. Collins, M.D., Ph.D. "And thus, it gives researchers a ready list of genes possibly involved in human disease."
In addition to its value as a research tool, the electronic gene map contains easily understood information useful to American students, who, by using computers at home or in the classroom, can have instant access to the most current information about our genetic constitution.
The goals of the HGP include building various sorts of maps that represent different aspects of the 3 billion subunits, or bases, of human DNA. The two major maps - called genetic maps and physical maps - contain molecular markers scattered throughout the human genome that help researchers locate the position of a gene. In most cases, genetic and physical maps - used in a technique called positional cloning - can tell a scientist the gene he or she is looking for is within a few million DNA bases of a marker on a specific chromosome. The slowest part of a gene hunt nowadays is finding and sorting through all the genes in the target region and determining exactly which one is responsible for the disease. Residing within those millions of bases may be hundreds of genes and much more DNA, irreverently termed junk DNA, because scientists don t yet know what it does.
Placing the 16,334 genes on the new map promises to change all that. It is the first step in the HGP's effort to locate and identify all 80,000 to 100,000 genes packaged along a human cell's 23 pairs of chromosomes. From the gene map, scientists will have immediate on-line access to information about which genes lie in the target region. The sequence of those genes may well suggest which ones go to the top of the list for further study.
This gene-hunting strategy, known as positional candidate cloning, has already been used successfully to locate and isolate genes responsible for Alzheimer's disease, inherited colon cancer and other serious disorders.
About 10 percent of the 16,334 points on the map represent fully characterized genes. The rest are distinct snippets of active genes, small stretches of DNA that fall somewhere within a gene to let researchers know it's there, but that still need more complete characterization to learn what the entire gene looks like and what it does. (Not all genes in the human genome are active all the time. Some carry out functions only during fetal development and then turn off completely. Others are active only in certain tissues. Some diseases and birth defects are caused by genes that turn on or off in the wrong place or at the wrong time.)
Efforts have been underway for the past few years in both publicly funded and commercial laboratories to identify spots throughout the human genome that contain active genes. Scientists developed a way to mark those spots by identifying short, unique segments of the genes, called expressed sequence tags, or ESTs. In just the past two years, the number of ESTs corresponding to genes in the human genome and stored in public databases has grown to nearly 500,000.
Although everyone recognized the value of mapping ESTs, there was so much redundancy in the databases, it just wasn t efficient or cost-effective to map them all, said NLM s Mark Boguski, M.D., Ph.D., who along with Greg Schuler, Ph.D., examined the DNA sequences of over 123,000 ESTs, and boiled them down to a unique set of gene identifiers. Meanwhile, scientists from around the world, including Tom Hudson, Ph.D., at the NHGRI-supported genome center at the Whitehead Institute in Cambridge, Mass., used various techniques to map the location of the ESTs throughout the human genome. Whitehead scientists, as well as those at Stanford University in Palo Alto, Calif., were among the largest contributors of points to the gene map.
Scientists from France, England, Canada and Japan also helped to map the ESTs, which resulted in the gene map tying together information from the genetic and physical maps of the human genome.
"One of the remarkable aspects of this project was that everyone came together to pool resources and build something bigger and more useful than any one group could have done individually," Boguski said.
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Last Updated: May 16, 2010