What are the genetic causes of food allergies?

About 5–8% of all children suffer from food allergies which can be caused by both genetic and environmental factors. A study has found five genetic risk loci that highlight the importance of skin and mucous membrane barriers and the immune system in the development of food allergies.

Led by the Max Delbrück Center for Molecular Medicine (MDC) and Charité – Universitätsmedizin Berlin, a study examined 1500 children who suffer from food allergies in Germany and the United States.

“Studies of twins suggest that about 80% of the risk for food allergies is heritable, but little is known so far about these genetic risk factors,” stated Professor Young-Ae Lee, a researcher at the MDC and head of Charité’s outpatient pediatric allergy clinic.

Certain foods can cause severe allergic reactions such as breathing difficulties, vomiting, diarrhoea and anaphylaxis, which can be fatal. While children often outgrow common food allergies or intolerances including chicken eggs and cow’s milk, peanut allergies can persist for life and are most commonly associated with anaphylaxis.

Published in Nature Communications, the genome-wide study looked at over five million genetic variations, called single nucleotide polymorphisms (SNPs), in each participant and compared the frequency of these SNPs with that of the control subjects. To confirm the allergy diagnosis, researchers used an oral food challenge test in which patients ingested small amounts of the suspected allergen in the hospital under emergency conditions.

“We know from clinical practice that as many as 80% of presumed food allergies are not actually allergies. These food sensitivities are frequently due to food intolerance rather than an allergic response,” said Lee.

Of the five genetic risk loci the study found, four of them showed a strong correlation with known loci for conditions such as atopic dermatitis and asthma, chronic inflammatory diseases like Crohn’s disease and psoriasis, and other autoimmune disorders.

The SERPINB gene cluster on chromosome 18 was identified as a specific genetic risk locus for food allergies. It involves 10 members of the serine protease inhibitor (serpin) superfamily. The genes in this cluster are expressed primarily in the skin and in the mucous membrane of the oesophagus. Consequently, researchers believe they play an important role in ensuring the integrity of the epithelial barrier function.

The study also found that four of the five risk loci were associated with all food allergies, with the only exception being the human leukocyte antigen (HLA) region, which is specific to peanut allergy cases.

By establishing potential hereditary markers of food allergies in children, the study builds the foundations for better diagnostic tests and possible treatment strategies.