In addition, the new map enabled researchers to quantify more precisely the rates of shuffling, or recombination, seen among different gene classes in the human genome. In their overview paper, researchers report that recombination rates vary more than six-fold among different gene classes. The highest rates of recombination were found among genes involved in the bodys immune defense, while the lowest rates appear among genes for chaperones, which are proteins that play a crucial role in making sure other proteins are folded properly. In general, genes that code for proteins associated with the surface of cells and external functions, such as signaling, were found to be more prone to recombination than those that code for proteins internal to cells.
While the reasons for the varying recombination rates remain to be determined, the findings pose interesting evolutionary questions. In their paper, researchers suggest that one explanation may be that some recombinations in areas of the genome that affect responses to infectious agents or other environmental pressures may be selected for because they provide a survival advantage.
A related study appearing in the same issue of Nature describes how the enhanced map can help pinpoint pivotal changes in the human genome that arose in recent history. These changes, now common among various populations worldwide, became prevalent through natural selection meaning they were somehow beneficial to human health. Although these DNA variants may still be important, their biological significance remains largely unkno
|Contact: Geoff Spencer|
NIH/National Human Genome Research Institute