Scientists find that a gene called EMSY is linked to food allergy.
In a paper published in the Journal of Allergy and Clinical Immunology, the Canadian team explains how it scanned millions of genetic markers in nearly 1,900 people and re-analyzed data pooled from six other genetic studies to reach the new findings.
Food allergy arises when the body's immune system wrongly reacts to a specific food as if it were a harmful substance. The symptoms and severity of the reaction can be different in different people, as well as different in the same person at different times. Sometimes they can be sudden and life-threatening, such as in anaphylaxis.
Research suggests that around 4 percent of children and teenagers are affected by food allergy in the United States, where eight types of food account for 90 percent of cases. These food types are peanuts, tree nuts, milk, fish, eggs, crustacean shellfish, soy, and wheat.
"One of the hurdles in developing new treatments for food allergies," explains co-first author Aida Eslami, a postdoctoral fellow at the University of British Columbia in Canada, "is identifying the specific genes and pathways we need to target."
The new study is the first to link a known gene called c11orf30/EMSY (EMSY) to food allergy.
"These results suggest that EMSY could be a useful target for predicting and managing food allergy treatments in the future."
Dr. Aida Eslami
More evidence of genetic basis
In their study paper, the researchers discuss how food allergy is the result of both genes and environment. Many studies have examined and confirmed the role of environment.
For example, the authors note that in the case of peanut allergy, the role of environment is supported by studies that show that "early oral exposure to peanut leads to development of tolerance."
Evidence that peanut allergy is rising rapidly and differs among nations also supports the idea that environment is important, as this "cannot be explained by genetic changes."
However, evidence on the genetic basis of food allergy is much less abundant. If there were more genetic clues, then researchers would be in a better position to develop tools that can identify children at risk.
For the new study, the Canadian researchers scanned more than 7.5 million genetic locations in the DNA of 850 people with peanut allergy and nearly 1,000 people without it to search for markers that might be linked to food allergy. They recruited the peanut allergy participants from the Canadian Peanut Allergy Registry.
The team also conducted a fresh analysis of results pooled from six other genetic studies of populations in North America, Australia, Germany, and the Netherlands.
Evidence of 'epigenetic regulation'
The results showed that EMSY was linked to a raised risk of peanut allergy as well as food allergy. The team also found evidence that five other genetic locations might be involved.
In previously published work, the researchers had already established that a fault in another gene called filaggrin can raise children's risk of peanut allergy. However, that study only offered a genetic explanation for around 20 percent of cases.
The new findings now offer many more genetic clues about the causes of peanut and food allergy, note the authors.
For instance, the new evidence suggests that some of the genetic markers may exert their influence by altering the expression of other genes through "epigenetic regulation."