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Map of the World

A new biological atlas focuses on African American genomics

A consortium led by scientists at the University of Oxford and Harvard Medical School has constructed the world’s most detailed genetic map.A WHOLE DIFFERENT ANIMAL: David Reich’s work in genetics often uncovers unexpected findings. Recently, for example, he and colleagues found that Africa has two distinct elephant species.<br/>Photo by Stephanie Mitchell/Harvard News Office

A genetic map specifies the precise areas in the genetic material of a sperm or egg where the DNA from the mother and father has been reshuffled in order to produce this single reproductive cell. The biological process whereby this reshuffling occurs is known as recombination. While almost every genetic map built so far has been developed from people of European ancestry, this new map is the first constructed from recombination genomic data of African Americans.

“This is the world’s most accurate genetic map,” says David Reich, an HMS professor of genetics, who co–led the study with Simon Myers, a lecturer in the Department of Statistics at the University of Oxford.

The researchers were surprised to find that positions on the map where recombination occurs in African Americans differ significantly from those in non–African populations.

“More than half of African Americans carry a version of the biological machinery for recombination that is different than Europeans,” Myers says. “As a result, African Americans experience recombination where it almost never occurs in Europeans.”

These findings—and the ability to map these genes more precisely—are expected to help researchers both understand the roots of congenital conditions that occur more often in African Americans and discover new disease genes in all populations.

“The places in the genome where there are recombination hotspots can also be disease hotspots,” says Reich. “Charting recombination hotspots can thus identify places in the genome that have an especially high chance of causing disease.” The findings appear in the July 21 issue of Nature.


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