Researchers create genetic map of human brain

About 84 percent of human genes are active in the brain, a finding that may help explain its complexities and a person's diseases, according to the most extensive DNA analysis of the organ to date.

In mapping the ways the genes link to the brain's structures, researchers at the Allen Institute for Brain Science, funded by Microsoft co-founder Paul Allen, found that the vast majority of the 20,000 genes in the human genome play a role in its function and architecture. That's more than in any other organ in the body, says a report published yesterday in the journal Nature.

Figuring out how the brain is organized may help in studying diseases, pointing out which part of it uses a gene that previous research has shown to be faulty, said study author Seth Grant of Edinburgh University. "The human brain is the most complex structure known to mankind," he said. "This allows us for the first time to overlay the human genome on the human brain."

Brains from two males ages 24 and 39 were mapped, and the genes' expression between the two were similar. Before today it wasn't clear how alike any two brains would be. They were of similar ethnicity, and their high degree of similarity suggests a "strong underlying common blueprint" for all human brains, the scientists wrote.

"It's breathtaking in its ambition," said Steve McCarroll of the Stanley Center for Psychiatric Research at the Broad Institute in Cambridge, Mass. "I was amazed to see how many anatomically defined sites they'd actually dissected out of each brain. In the effort to make a geographic atlas of regional gene expression it goes really far beyond anything that's been done before."