If hay fever slays you, ragweed has you depleting every tissue box around, or certain foods have you flaring up with hives or grabbing for your epi-pen, you might wonder how you got so unlucky. Allergies can put a big damper on your quality of life.
So why are you allergic while the guy or gal next door is allergy-free? The answer is complex. Environment plays a role, and so does age (young people are generally more prone to food allergies, for example, than adults). And genetics are also a big piece of the puzzle. That’s right, you can blame Mom and Dad for at least some of your allergic misery. (But don’t be too hard on them—you may unwittingly pass the same allergic curse down to your kids.)
Studies generally show that if one of your parents has allergies, you have a 50 percent chance of developing allergies yourself. If both of your parents have allergies, your risk increases to 75 percent. But new research has shed even more light on the tie between genetics and allergies. Here’s a closer look at findings from recent studies.
Professor Hasan Arshad, DM, a consultant in allergy and immunology at Southampton General Hospital in England, launched a long-term study of the role that gender plays in hereditary allergies. He tracked nearly 1,500 patients from birth to 23 years over the course of 18 years with periodic checkups to assess their allergies. Parents and children were subjected to regular diagnostics, including skin prick tests, blood tests, and spirometry to measure allergic sensitivities.
The results, published in the Journal of Allergy and Clinical Immunology (JACI), found that the risk of asthma in boys is only increased if their fathers suffered from the condition. If mothers had asthma, it doubled the risk in their daughters but not their sons. Furthermore, maternal eczema led to a 50% increase in the risk of eczema in daughters, and paternal eczema led to the same increase in sons.
A genetic basis for food allergies
With the rise of food allergies in recent years (up by 50 percent between 1997 and 2011), there has been a lot of attention on what causes them and how to treat them. This has fueled a number of studies on the connection between food allergies and genetics.
In a study published in the Journal of Allergy and Clinical Immunology in 2017, a Canadian research team examined over 7 million genetic markers in nearly 2,000 people and also re-examined data from six other genetic studies. Through this exhaustive research, the team was able to pinpoint a new gene (known as EMSY) associated with peanut allergy.
Another 2017 study published in Nature Communications shed additional light on the influence of genes on food allergies. This study examined 1,500 children with food allergies in Germany and the U.S. It was remarkably comprehensive, examining more than 5 million genetic variations in each participant in the study. This study discovered a total of five genetic risk “loci”—defined as positions of genes or mutations on a chromosome—that drive food allergies.
These are just two of many recent studies that show strong genetic underpinnings for food allergies.
More symptoms linked
Many of these genetic studies show that the genes behind food allergies also contribute to other types of allergy. For example, in the JACI study, the EMSY gene connected to food allergy had already been linked to eczema, asthma, and other allergy-related conditions. Thus, it seems to play a broad role in making people more prone to allergies in general.
In the Nature Communications study, four of the five genetic markers for food allergies also showed a strong correlation with those for atopic dermatitis (eczema) and asthma. Specifically, one gene cluster on chromosome 18 tied to food allergies expresses itself in the skin and mucous membrane of the esophagus. This finding suggests that the genes may be responsible for problems with the integrity of the “epithelial barriers” in the skin—which could lead to eczema—and airways—which could lead to upper respiratory allergy symptoms, including asthma.
There is much more research to do to understand the scope of the relationship between allergies and the genetics behind them, but these advanced new studies are putting us on a path to better predicting allergies and knowing how to prevent and treat them.
Environment matters, too
Of course, while genetics may make you more prone to allergies, as mentioned earlier in the article, environment plays a critical role in their development as well.
There is plenty of research showing that increased exposure to allergens can heighten allergic sensitivities. This can explain why 8 to 12 percent of people who work in the health care industry have latex allergies as compared to 1 to 6 percent of the general population (think latex gloves).
It can also explain why you can move to an area with new pollens and not have any symptoms, then start developing sensitivities to those pollens over time. As an example, many transplants to Central Texas will sail through their first winter and spring without any problems, only to have the dreaded Mountain Cedar pollens in the area catch up to them and cause raging hay fever within a year or two.
So yes, allergies are genetic—to a point. And while we don’t have all the answers, new research is helping us understand more about prediction, prevention, and environmental and food allergy treatment, so maybe your children or your children’s children will have it just a little easier during allergy season than you do.