one out of four Americans, making allergies more common than heart disease, cancer and diabetes combined. For many people, allergies involve only symptoms that are a nuisance, like sneezing or itchy eyes. But for some, contact with certain substances can lead to life-threatening anaphylactic shock. To study this mysterious and growing problem, we’ve released our first allergy survey.Allergies occur when your body reacts to a normally harmless substance, called an allergen, like it’s a dangerous invader. Your immune system produces IgE antibodies that recognize the allergen and trigger the release of histamines. While histamines normally help protect your body against infections, they can cause allergy symptoms when released inappropriately. This is why many allergy medications are called “anti-histamines”.The biological process of how symptoms occur after the release of histamines is relatively well-understood, but the question of why the immune systems of people with allergies react to otherwise inoffensive substances like pollen or peanuts remains. There is a growing body of evidence that supports the “hygiene hypothesis.” This theory says that our immune systems need early exposure to parasites like roundworms and tapeworms to mature properly. Without such exposure the risk of developing allergies is increased. This fits with the observation that allergies are more common and generally on the rise in industrialized countries where parasite infections are far less common than in the developing world.It is also clear, however, that genetics play a large role in whether you develop allergies. Having a family history of allergy puts you at much higher risk for also having an allergy, although it may not be the same type. For example, a family history of asthma, which is a type of allergic disease in most cases, puts you at higher risk for a food allergy. While a few genes have been shown to be associated with allergy, the genetic picture is far from complete. If by learning more about the genetics of allergy we could help predict which children may be more likely to develop a dangerous food allergy for example, precautionary measures could be taken. In addition, we may discover better ways to treat different allergies.At best, allergies are annoying. At worst, they’re deadly. You can help us take the first steps to understanding the genetics of allergy by completing our new allergy survey. In the meantime, I’ll be investing in Kleenex!