Is DNA to blame for seasonal allergies and ACHOO syndrome?
Sometimes, the sneeze will hit you before you even know it’s happening. Your face crinkles, your head cocks back, and you propel particles from your nose at speeds exceeding 100 miles per hour. Such a forceful reaction is more than funny (and slightly gross)—it’s the product of evolution. Our noses offer potentially harmful invaders a quick route into the body. To defend us from things like bacteria and fungi, we’ve evolved mucus to slow them down, and sneezing to expel them.
Among the top culprits for inducing a sneeze are seasonal allergies. In academic literature, you may see it referred to allergic rhinitis. As the name implies, this is a condition where a person is prompted to sneeze in reaction to some nearby pollen that’s a part of the natural seasonal cycle for plants. Aside from pollen, there’s a whole host of things that can promote a sneeze: cat dander, bacteria, fungi, pepper, and—for some—sunlight. People who sneeze in response to sunlight are said to have autosomal dominant heliopthalmic outburst syndrome, or ACHOO syndrome. People who have this condition know exactly what we’re talking about. For them, walking out from a shaded area into the bright sunlight might cause a sudden sneeze.
Studies looking into these conditions have noticed that both ACHOO syndrome and seasonal allergies may run in families, which suggests a possible genetic component to both of them. These studies have identified numerous variants in the DNA that may predispose someone to having one of these conditions, but it’s important to remember that DNA is just one piece of the puzzle—neither seasonal allergies nor ACHOO syndrome appear to be entirely caused by genetic factors. With complex traits like sneezing, there’s often a mixture of environmental factors and multiple, small-impact genetic factors that contribute to the final trait1-3.
2Gao, Zhiwei, Donna C Rennie, and Ambikaipakan Senthilselvan. “Allergic Rhinitis and Genetic Components: Focus on Toll-like Receptors (TLRs) Gene Polymorphism.” The Application of Clinical Genetics 3 (2010): 109–120. PMC. Web. 14 Aug. 2018.
3Dean, Laura. “ACHOO Syndrome.” Advances in Pediatrics., U.S. National Library of Medicine, 27 July 2015, http://www.ncbi.nlm.nih.gov/books/NBK109193/. Web. 14 Aug. 2018.