The map, dubbed a "Brain Atlas" by its creators, details the locations of more than 21,000 genes in a male mouse's brain. Researchers have placed the complete three-dimensional map on the Internet and opened it up to scientists and the public free of charge.
Scientists now spend months, and sometimes years, performing what essentially amounts to busy work: confirming that genes they suspect of playing a role in disease actually operate in a particular brain region.
The map will let scientists immediately locate such genes, at least in the mouse, potentially taking away the need for the confirmatory work. This means genes can now be ruled in or ruled out in a matter of minutes or hours, researchers said.
"All of the prospecting has been done. You can go there and start mining (the genes) yourself," said David Anderson, a California Institute of Technology brain researcher. He is a member of the board of the Allen Institute for Brain Science, which reported the project.
The atlas is the Seattle-based Institute's first major project since it was founded three years ago with a $100 million endowment from Allen. It follows the publicly-funded Human Genome Project, which opened a complete catalogue of the human genetic sequence to the public in 2003.
Biotech and pharmaceutical companies already generate their own location maps for targeted genes in the brain. Anderson said the Allen Institute's map is not only the largest created, but is also the first to be shared worldwide with all comers.
"We are very unique in that we're making all of this data publicly available," he told reporters at a briefing on Capitol Hill in Washington.
About 90 percent of the genes in a mouse's brain have a human counterpart, so the mouse atlas can serve as a close analogue for gene locations in people, researchers said. But research on the atlas has already shown more genetic complexity in the brain than scientists originally suspected. More than 80 percent of the genes in a mouse's DNA are expressed in the brain, and almost no genes are found in only one brain region.
Thomas Insel, M.D., who directs the National Institute of Mental Health, said in an interview that the new Brain Atlas, along with the Human Genome Project and related maps, have cut up to five years of basic research time off genetic disease studies. "If you know where something is expressed, it helps explain what it might do," he said.
Still, he cautioned that the Atlas is only a "snapshot" of a mouse's life and will not shed light on the key question of how genes turn on and off during aging. "This answers the 'where' question. It leaves out a couple of questions. One that this leaves out is the 'when' question," Insel said.
Allan Jones, Ph.D., the Allen Institute's chief scientific officer, said the institute is now moving to compile a gene atlas of the human neo-cortex, the folded structure that forms the outer layers of brain tissue. That project requires only about one-quarter the data used to construct the mouse atlas, he said.
The laboratory has no plans to generate a genetic map of the complete human brain, Jones said, noting that such a project would take "orders of magnitude" longer to complete than the three years needed for the mouse project. "The scale would be enormous," he said.
SOURCES: David Anderson, professor of biology, California Institute of Technology; board member, Allen Institute for Brain Science. Thomas Insel, M.D., director, National Institute of Mental Health. Allan Jones, Ph.D., chief science officer, Allen Institute.
By Todd Zwillich
Reviewed by Louise Chang, M.D