A new study published in the online edition of Trends in Genetics reveals that the HLA genes, which help the immune system differentiate between foreign invaders and the body's own cells have been evolving faster than previously thought.
The resulting degree of variation improves our ability to fight off disease, but could also present challenges to current worldwide efforts aimed at identifying potential donors for patients undergoing stem cell transplantation.
"This new work makes clear the daunting and near hopeless challenge of keeping track of the continuous output from the HLA mutational spigot," says first author William Klitz, from the University of California, Berkeley.
The difficulty is that within the human population, HLA genes are mutating rapidly and Klitz estimates that more than a million variants exist in the current population. Trying to identify all the variants will be nearly impossible and ultimately pointless, according to Klitz, because of how quickly these genes are evolving. This rapid evolution is a boon in some ways because it means that, at the population level, our immune systems are getting better at fighting off pathogens. For transplant recipients, however, the most likely implication is that the best chance for a match will be found in first-degree relatives rather than in a worldwide search for donors.