HARVARD GAZETTE ARCHIVES

Charles Lee (right) and John Iafrate discuss the surprising gaps they found in the human genome. (Staff photo Stephanie Mitchell/Harvard News Office)

Contrary to expectation, a startling number of large variations have been found in the human genome. The genetic blueprints for humans were thought to be 99.9 percent similar, but researchers at Harvard Medical School and the University of Toronto in Canada have accidentally discovered large chunks of missing or added DNA in normal, healthy people.

"We were extraordinarily surprised to see that some people have so much more or less DNA," says Charles Lee, a geneticist and assistant professor at Harvard. "This is very exciting. It could explain differences in human nature, and help us identify people who are more prone to certain diseases."

The researchers looked at 55 healthy, unrelated men and women, and they discovered 255 regions with relatively large gains or losses in their DNA. Some experts speculate that these variations could be responsible for differences in intelligence and behavior, as well as predispositions to certain diseases.

"This discovery may help us to better understand the nature of humanity," says Lee.

For full Gazette story, see http://www.news.harvard.edu/gazette/2004/08.26/13-genegaps.html.