Scientists in the US have created a genetic map for African American populations that reveals the precise locations across the genome where DNA from a person's father and mother have been stitched together. UCLA life scientists and colleagues did this by analyzing a biological process called "recombination," which results in new genetic combinations that are then passed on to the children.The map that was produced will help scientists learn the roots of certain diseases and discover genes that play key roles."Research aimed at finding disease variants will be improved by this tool, which could lead to better medications to help ameliorate the effects of those disease variants," said the senior author of the research, John Novembre, a UCLA assistant professor of ecology and evolutionary biology and of bioinformatics. "Health researchers can use a recombination map to refine where a disease gene might be."This research was one of the first times that recombination was not studied using data from Europe. "Now we have a map for African Americans that researchers can use as a tool, instead of using a European map or an African map," says Novembre.Recombination rates between Europe and Africa may look very similar on the surface, explains Novembre, "but there are clear differences in recombination between Africans and Europeans, and African Americans tend to have a map that is a mixture between the African and European map, reflecting the mixture that took place between these two groups."Explaining recombination, Novembre says, "When we pass on DNA to our children, we stitch together the DNA we received from our mother and father. The resulting DNA alternates between DNA from your mother and from your father, and the recombination points are the boundaries. Those points could be chosen uniformly across the whole chromosome, but studies have found that recombinations occur in some locations in the chromosome more than in others. Locations in the chromosome have particular recombination rates — the rate at which break points occur in that location."Comparing this African American recombination map with that of other populations enables researchers to locate recombination hot spots, which have highly elevated rates of recombination.