The Most Accurate Human Genetic Map to Date

A map created using DNA sequence from African-Americans highlights "hot spots" in the genome, which are often linked to disease.

Researchers have developed the most sophisticated map yet of the human genome, highlighting the regions where maternal and paternal chromosomes recombine, or swap parts. Recombination is one of the driving forces of genetic variability, which underlies evolution.

The genetic "hotspots" where recombination is most likely to take place are also linked to inherited diseases, since these regions are vulnerable to errors in the genetic code. "When recombination goes wrong, it can lead to mutations causing congenital diseases, for example diseases like Charcot-Marie-Tooth disease, or certain anemias," said Simon Myers, a lecturer in the Department of Statistics at the University of Oxford who led the research, in a release from Harvard Medical School.

"Charting recombination hotspots can thus identify places in the genome that have an especially high chance of causing disease," said David Reich, professor of genetics at Harvard Medical School, who co-led the study, in a release from Stanford.

The map is the first constructed from recombination data collected from African Americans. Previous maps have used genome information primarily from people of European decent. Researchers found that African Americans and Europeans have different recombination sites. 

According to the release;

These findings are expected to help researchers understand the roots of congenital conditions that occur more often in African Americans (due to mutations at hotspots that are more common in African Americans), and also to help discover new disease genes in all populations, because of the ability to map these genes more precisely.

The new map is so accurate because African American individuals often have a mixture of African and European ancestry from over the last two hundred years. David Reich and Simon Myers are experts in analyzing genetic data to reconstruct the mosaic of regions of African and European genetic ancestry in DNA of African Americans. By applying a computer program they previously wrote, Anjali Hinch identified the places in the genomes where the African and European ancestry switches in almost 30,000 people, detecting about 70 switches per person. These areas corresponded to recombination events in the last few hundred years. Thus, the researchers identified more than two million recombination events that they used to build the map.