Researchers have discovered a genetic mutation unique to African Americans that could help explain why blacks are so susceptible to asthma

Prior studies looking for asthma genes have turned up several, but most of the studies have been too small to confirm these genes or to detect genetic changes unique to different races. The new study pools research from nine different research groups looking for genes associated with asthma among ethnically diverse North American populations. It confirmed four genes that had been seen in previous studies and a fifth that shows up only in people of African descent. "This is the first discovery of a gene where we see a signal in African Americans only," Dan Nicolae of the University of Chicago, a study author and co-chair of a national research consortium called EVE that identified the gene, said. "The rates of asthma in different ethnic groups are different. African Americans have shown increasing asthma rates. We don't know why. It can be due to changing environmental risk factors," Nicolae said. But, he said, the new findings suggest that genetics also play a significant role. "Understanding these genetic links is an important first step toward our goal of relieving the increased burden of asthma in this population," said Dr. Susan Shurin, acting director of the National Heart, Lung, and Blood Institute, one of the National Institutes of Health, which co-funded the study. Asthma affects more than 300 million people globally, but effects vary widely. According to the researchers, U.S. asthma rates in 2001 to 2003 ranged from 7.7% among European Americans to 12.5% among African Americans. Because the study was so large and ethnically diverse - including data on European Americans, African Americans, African Caribbeans and Latinos - it enabled the researchers to find the new gene variant that exists only in African Americans and African Caribbeans. This new variant, located in a gene called PYHIN1, is part of a family of genes linked with the body's response to viral infections. The researchers were very excited when they realized that it didn't exist in Europe.