Two new genetic maps of African-Americans reveal that people of West African descent have more hot spots where chromosomes mix and match genes than people of European heritage do.
Until recently scientists knew next to nothing about the process humans use to mix and match parents’ genes to create a unique combination in a child, says Chris Spencer, a population geneticist at the Wellcome Trust Centre for Human Genetics at Oxford University in England. This process, known as recombination, also helps chromosomes stick together until it is time to separate during egg and sperm production.
Previously, scientists could trace recombination only in families, and they thought that the exchange of genetic information happened at random. These new studies are the first to describe a way to use unrelated people to map genetic shuffling in populations. The studies also demonstrate that the genetic handover actually takes places at predetermined locations on chromosomes. “They make real contributions to methodology, and they really tell you something about biology,” says Spencer, who was not involved in either study.
People of West African ancestry have about 2,500 recombination hot spots that are inactive in people of European ancestry, David Reich of Harvard Medical School, Simon Myers of Oxford and large team of collaborators report online July 20 in Nature.