HIGH SPEED GENE MAPPING
By Sean Henahan, Access Excellence
DENVER A new gene mapping technique should greatly speed
the work of geneticists involved in the international Human Genome Project,
Researchers at the University of Colorado Health Sciences Center have
developed a method called "STS gene mapping". The method developed
by Dr. James Sikela, PhD, and his team uses a mapping marker (a genetic
"bar code" ) called an STS, which can be used to determine the
chromosomal location of any segment of DNA. STS stands for 'sequence tagged
In 1991, Sikela and associates showed how STSs could be rapidly generated
from human genes so that each gene would have its own unique STS. Each STS
could then be easily assigned to a chromosome, thus simultaneously mapping
the corresponding gene. The team has now refined the technique, using new
tools that have recently become available, so that a gene's exact location
on a chromosome can be determined.
Locating genes associated with specific diseases has traditionally been
a slow and painstaking process. The first step is usually to determine the
approximate location of a disease gene on one of the 23 chromosomes. However,
each section of a chromosome may have several hundred genes on it, so each
gene must be located and tested individually to determine which one triggers
a disease. This approach can take several years to complete. In the case
of Huntington's disease, for example, it took researchers 10 years to identify
the gene after the first marker was discovered.
Only about 5 percent of the estimated 50,000 to 100,000 human genes have
been mapped so far. The new technique is already being used by an international
consortium of scientists to develop the world's first detailed map of human
genes. With the gene map, researchers will be able to quickly find the genes
in virtually any region of any chromosome. Using the new method, researchers
hope to produce a comprehensive gene map, showing the location of the majority
of human genes by 1997.
"A comprehensive gene map will permanently change the way the majority
of disease genes are discovered," said Dr. Sikela, associate professor
of pharmacology. "Instead of spending many months and often years trying
to find all the genes in a chromosomal region thought to contain a disease
gene, a computer search of the gene map will get the same information in
a matter of seconds."
For more details on the new technique, see Dr. Sikela's article in the
August 1995 issue of Nature Genetics.
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