Hereditary causes of childhood food allergy
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 causes of food allergies in children in Germany. Researchers have now gained more clarity about the hereditary causes of such allergies.
Food allergies are increasing
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 egg, wheat, peanuts and hazelnuts. Adolescents and adults generally react more often to raw vegetables and fruits, nuts, fish, crustaceans and molluscs, ”says the DAAB website. Researchers have now gained more insight into the role genes play in such allergies.
The most common food allergy triggers in children
About five to eight percent of all children suffer from food allergies. They mostly appear in the first years of life and are noticeable by an itchy rash and swelling of the face shortly after eating.
Food allergies can also cause severe allergic reactions with shortness of breath, vomiting or diarrhea: they are the most common cause of childhood anaphylaxis. It is the most severe form of an immediate allergic reaction that can be fatal.
In Germany, chicken egg, cow's milk and peanut are the most common triggers of food allergies in children. In contrast to allergies to cow's milk and hen's egg, which often disappear within a few years, peanut allergy usually persists.
For those affected, this means that they have to follow a strict diet for life and have to carry emergency medication with them.
Hereditary factors play a major role
The causes of food allergies are complex and are based on an interplay of genetic material and the environment.
"Based on twin studies, we suspect that about 80 percent of the risk of food allergy is determined by hereditary factors," said Prof. Young-Ae Lee from the Max Delbrück Center for Molecular Medicine (MDC) Berlin in a statement.
"But so far little is known about the genetic risk factors," says the scientist, who is also director of the university outpatient clinic for pediatric allergy, Charité - Universitätsmedizin Berlin.
Study is characterized by a reliable diagnosis of the disease
In a genome-wide association study, her team examined around 1,500 children with food allergies from Germany and the United States.
The scientists examined more than five million hereditary variants, so-called SNPs, for each study participant and compared their frequency with that in control subjects.
Scientists from Berlin, Frankfurt, Greifswald, Hanover, Wangen and Chicago were involved in the study, which was published in the journal "Nature Communications".
As stated in the communication, the scientific work is not only characterized by its size, but also by the reliable diagnosis of the disease.
Many food allergies are not
In contrast to other studies, the diagnosis of food allergy was confirmed by a provocation test.
It is a time-consuming procedure in which the patient in a hospital is on call to eat the suspect food in small quantities to check whether he is allergic.
“We know from practice that up to 80 percent of the suspected food allergies are not. It is often an intolerance and not an allergy, ”said Prof. Lee.
A total of five gene locations for food allergies were found in this study.
Four of them show strong agreement with known gene locations for neurodermatitis 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
The team around Lee identified the SERPINB gene cluster on chromosome 18 as a specific gene location for food allergies. This is a group of ten representatives of the "serine protease inhibitors".
The genes in this group are mainly expressed in the skin and in the lining of the esophagus. The scientists therefore suspect that they are important for the integrity of the epithelial barrier function.
Another important finding from the study is that four out of five identified gene locations are associated with all food allergies. Only the HLA locus, which is specific for peanut allergy, appears to be an exception.
According to the scientists, the study is a starting point for the development of better diagnostic tests for food allergies and for further research into their causal mechanisms and possible therapies.
Parents should avoid the unfounded avoidance of food and contact a specialist if they suspect a food allergy. (ad)