The same genes may influence asthma, hay fever, and eczema risk.
An international study published by Nature Genetics indicates that more than 100 genetic factors may play a role in common allergies.
The authors said that this was the first study to pinpoint specific genetic risks that are shared among asthma, hay fever, and eczema, which affect millions of individuals.
"Asthma, hay fever and eczema are allergic diseases that affect different parts of the body: the lungs, the nose and the skin," said senior author Lavinia Paternoster, PhD.
Asthma is an allergic condition that can result in airway inflammation, swelling, and extra mucus production, which makes it difficult to breathe. Similarly, hay fever—commonly known as seasonal allergies—is characterized by watery eyes and sneezing, while patients with eczema experience an itchy, inflamed skin rash.
"We already knew that they were similar at many levels,” Dr Paternoster said. “For example, we knew that the 3 diseases shared many genetic risk factors. What we didn’t know was exactly where in the genome those shared genetic risk factors were located.”
Included in the genome-wide association study were 360,838 individuals.
The authors identified a total of 136 risk variants for the allergic conditions, 73 of which were not previously discovered, according to the study.
If inherited, individuals may have a significantly higher risk of developing asthma, hay fever, or eczema.
"It’s really exciting that we have been able to find so many genetic variants that influence these diseases which affect so many people,” Dr Paternoster said.
Additionally, the investigators found that disease-specific effects were present for 6 variants, suggesting that these conditions have shared risk factors, according to the study.
Significantly, the authors found that existing drugs may modify the 6 genes to provide relief for symptoms of the allergic conditions.
The authors also discovered that asthma, hay fever, and eczema may coexist due to inherited variants that change immune-related gene expression, according to the study.
"Some of the genes implicated in our study already have drugs available that can target them,” Dr Paternoster said. “So, these drugs (currently used for other conditions) may be effective in treating allergic conditions. The next step is to test these in the laboratory."