A recent meta-analysis of hay fever (allergic rhinitis) identified 41 risk loci for the condition, including 20 loci not previously associated with allergic rhinitis. According to the authors of the comprehensive study that includes data from more than 30 studies and almost 900,000 participants from Europe, their findings could help identify novel targets for treatment and prevention of hay fever.
"This is the largest genetic study ever conducted into hay fever. The scope of the study has allowed us to learn more about the allergy, and it has only been possible with the help of many other research groups from around the world. The risk genes we have mapped can help us understand what causes hay fever. And in the longer term this will be helpful when it comes to developing drugs and better treatments for the allergy," says Klaus Bønnelykke, clinical research associate professor at the department of clinical medicine, University of Copenhagen.
"Genes are very important, and twin studies show that in more than half of sufferers, the allergy is caused by genetics. We can also see that a great many cases must be due to environmental factors, since the number of people with hay fever has increased over the past 100 years. The allergy is not spreading that fast due to genetic changes. It takes tens of thousands of years for genetic makeups to change. Therefore, I believe that the rise is likely to be caused by an interplay between risk genes like the ones we have found in this study and various environmental factors that trigger the allergy in people with risk genes," Bønnelykke explains.
In the study published yesterday in Nature Genetics, the researchers also found an overlap between risk genes for hay fever and risk genes for autoimmune diseases such as type 1 diabetes, rheumatoid arthritis, and inflammatory bowel disease. As with allergies, the number of people with autoimmune diseases has risen sharply in recent years.
"Our study helps identify genetic commonalities which may be a key to understanding why these illnesses are all on the rise. It seems there are some common factors in the western lifestyle that are causing these illnesses to become more widespread, but we haven't yet understood why. The genetic overlap we have observed seems to suggest that it is the same genes that trigger these illnesses, at least in part. This is important information when trying to understand the mechanisms and causes. It may matter not just to understanding hay fever but also to understanding autoimmune diseases,” adds Bønnelykk.