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Whitehead Researchers Make Complete Mouse Genome Map

By Orli G. Bahcall
associate news editor

The Whitehead Institute has finished the world's first complete map of the mouse genome, a major goal of the Human Genome Project. The Human Genome Project is an effort to sequence and understand the entire human genetic code.

The mouse mapping project was made a part of the international genome project because "there are so many striking similarities between the mouse and the human," said Dr. Joyce Miller, project leader of the Whitehead Genome Center.

Comprehensive maps of the human genome were completed by Whitehead and the National Institutes of Health in December. The mouse map appears in the March 14 issue of Nature.

The Whitehead Genome Center "signed on to complete the mapping of the mouse genome from start to finish," said Miller.

The work was supported by the National Center for Human Genome Research at NIH.

It is crucial to map both the mouse and the human genomes because research on human disease often focuses on laboratory mouse models, according to Professor of Biology Eric S. Lander, also director of the Whitehead/MIT Center for Genome Research.

"Mice have diseases that are analogous to human diseases," Miller said. For example, mice have several versions of epilepsy and high blood pressure, she said.

Many insights about genetic diseases have already been derived from this map, including high blood pressure, colon cancer, and obesity, Miller said.

The mouse genome contains complements of some 100,000 genes found in humans, representing a 75 percent match with those of their human counterparts.

The mouse "serves as an excellent model, [in that] most mammals are related in their DNA anywhere from 40 to 60 percent," Miller said.

Use of a mouse model allows researchers "to do a lot of experiments in mice that can't be done in humans, but mice are similar enough to humans that their diseases are similar," Miller said.

"Many genes were identified in humans because they were found first in mice and [researchers were subsequently] able to find the analogous chromosome in humans," Miller said.

The mouse "serves as an excellent stepping stone, it is small, easy to use and easy to study," Miller said.

Specific traits can be studied

"With the completion of dense maps of mouse and man," Lander said, "it is now possible to dissect virtually any genetic trait."

It is possible to extend these maps further, they are more than adequate for genetic studies, Lander said. Instead, efforts should be focused on determining the complete three billion-letter DNAsequence of these two mammals, he added.

"Understanding how different genes work together to affect the timing, severity, and outcome of diseases such as cancer and diabetes will lead to important new strategies for disease prevention and therapy," Lander said.

Once scientists know the chromosomal location of a particular gene, they can get the corresponding large piece of DNA, sequence it, and clone out the specific gene, Miller said.

"The combination of using the genetic and physical map greatly speeds the search for a particular gene," Miller said.