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Map of African-American genes a new guide for disease research

By Carolyn Y. Johnson
Globe Staff / July 21, 2011

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An international team of scientists led by a Harvard researcher published a sweeping genetic map of African-Americans yesterday, an accomplishment that could help illuminate the biological basis for disease.

The study analyzed data from 30,000 African-Americans and highlights a subtle but surprising variability between people of different ancestry: During the genetic shuffling that occurs when DNA from a mother and father mix to create their children’s sperm and eggs, African-Americans’ genetic material combines differently from that of Europeans.

“The genetic map is one of the fundamental tools that people use for interrogating the genome, to find disease genes and to find risk factors. This is a big leap forward in one’s ability to do that,’’ said David Reich, a Harvard Medical School genetics professor who headed the study with Simon Myers of University of Oxford.

To create the detailed map, published in the journal Nature, 81 researchers from around the world combed data from five earlier studies that examined genetic risk factors among African-Americans for cardiovascular disease and lung, breast, and prostate cancer.

Researchers found that among 2.1 million regions in the genome where genetic material is swapped during the shuffling process, known as recombination, there are about 2,500 spots that are vastly more active in West Africans than in Europeans. The reason, they found, has to do with a difference in a gene called PRDM9.

Other studies have shown that errors at the spots where genetic material is exchanged can lead to rare genetic diseases. The new study provides areas that researchers may be able to investigate in their quest to better understand the roots of diseases more common to African-Americans. But because the map is the single most comprehensive genetic map charted so far, it may provide clues in the hunt for genes that cause disease in all people.

John Novembre, a member of the interdepartmental program in bioinformatics at University of California, Los Angeles, said the study, with a study he published yesterday in Nature Genetics, provides a powerful new tool.

“Documenting these recombination rates is really important for disease studies, for multiple reasons,’’ Novembre said. “When it goes wrong, it can cause large-scale rearrangements of chromosomes that end up creating heritable diseases.’’

Carolyn Y. Johnson can be reached at cjohnson@globe.com.

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