Genetic causes of food allergies in children

Hereditary causes of food allergy in childhood

More and more people in Germany are allergic to certain foods, including many children. Chicken eggs, cow's milk and peanuts are the most common cause of food allergies in children in Germany. Researchers have now gained more clarity on the hereditary causes of such allergies.

Food allergies increase

Food allergies have been increasing for many years. According to estimates by the German Allergy and Asthma Association (DAAB), around six million people are affected in this country. "The main triggers in infants and children are cow's milk, soy, chicken eggs, wheat, peanuts and hazelnuts. As a rule, adolescents and adults are more likely to react to raw vegetables and fruits, nuts, fish, crustaceans and molluscs, "reads the DAAB website. Researchers have now gained more insight into the role of genes in such allergies.

Chicken eggs, milk and peanuts are the most common triggers of food allergies in children in Germany. One study has now clarified the role of genes in such allergies. (Image: Maksim Kostenko / fotolia.com)

The most common triggers of food allergies in children

About five to eight percent of all children suffer from food allergies. They usually appear in the first years of life and make themselves felt by itchy rash and facial swelling shortly after eating.

Food allergies can also cause severe allergic reactions with dyspnoea, vomiting or diarrhea: they are the most common cause of childhood anaphylaxis. It is the most severe form of immediate allergic reaction that can be fatal.

In Germany, chicken egg, cow's milk and peanut are the most common causes of food allergies in children. In contrast to allergies to cow's milk and chicken eggs, which often disappear within a few years, the peanut allergy usually persists.

For sufferers, this means that they have to adhere to a strict diet for a lifetime and have emergency medications with them.

Hereditary factors play a major role

The causes of food allergies are complex and are based on an interaction between genetic material and the environment.

"Based on twin studies, we suspect that approximately 80 percent of the risk of food allergy is caused by hereditary factors," said Prof. Young-Ae Lee of the Max Delbrück Center for Molecular Medicine (MDC) Berlin in a statement.

"But so far little is known about the genetic risk factors," said the scientist, who is also head of the Outpatient Clinic for Pediatric Allergology, Charité - Universitätsmedizin Berlin.

The study is characterized by a reliable diagnosis of the disease

In a genome-wide association study, her team examined about 1,500 children with food allergies from Germany and the USA.

The scientists examined more than five million hereditary variants, known as SNPs, in each study participant and compared their frequency with those in control subjects.

The study, published in the journal "Nature Communications", involved scientists from Berlin, Frankfurt, Greifswald, Hanover, Wangen and Chicago.

As the communication states, the scientific work is characterized not only by its size, but also by the proven diagnosis of the disease.

Many food allergies are none

In contrast to other studies, the diagnosis of food allergy was confirmed by a provocation test.

This is a complex procedure in which the patient in a clinic in emergency preparedness takes the suspicious food in small quantities to check if he is allergic.

"From practice, we know that up to 80 percent of suspected food allergies are none. Often it is incompatibilities and no allergies, "said Prof. Lee.

In this study, a total of five loci for food allergies were found.

Four of them show strong agreement with known loci for atopic dermatitis and asthma, but also with other chronic inflammatory diseases such as Crohn's disease, psoriasis and autoimmune diseases.

Starting point for the development of better diagnostic tests

As a specific locus for food allergies, Lee's team identified the SERPINB gene cluster on chromosome 18. This is a group of ten representatives of the "serine protease inhibitors.".

The genes of this group are mainly expressed in the skin and in the mucosa of the esophagus. The scientists therefore suspect that they are important for the integrity of the epithelial barrier function.

Another important finding of the study is that four out of five identified loci are associated with all food allergies. Only the peanut allergy-specific HLA locus seems to be an exception here.

The study, according to scientists, provides a foundation for developing better diagnostic tests for food allergies and further exploring their causal mechanisms and potential therapies.

Parents should refrain from unfounded food-avoidance and contact a specialist if they suspect a food allergy. (Ad)