Determining the risk of development of atopic diseases based on genetic susceptibility factor has become a routine matter due to a large amount of scientific research in this area. For instance, it has been proved that atopy in both parents indicates an extremely high risk of development of similar diseases in the child. Researches and clinical observations suggest that genetic susceptibility to atopy depends on many factors: most often, the researchers note the significant role of interleukins (in particular, IL-4 and IL-13), Langerhans cells, and dendritic cells.
However, with all the diversity of atopic diseases (allergic rhinitis, allergic conjunctivitis, urticaria and many others), only respiratory allergies (bronchial asthma) were 100% proven to have a high risk of passing down through genes from parents to their kids. Patients suffering from this disease have a specific atopy gene.
This article describes genetic foundations of atopic dermatitis. Various molecular-genetic studies are aimed at identifying the main locus of this disease. In this article, we will discuss three main issues concerning the heritability of atopic dermatitis which seem very important for practitioners such as dermatologists or cosmetologists.
Is atopic dermatitis proven to be an inherited disease?
Clinical studies concerning the issue of genetic susceptibility to atopic diseases were mostly carried out using genetic twin studies. According to the data collected by the pediatric allergist Schulz-Larsen, the concordance of atopic dermatitis in monozygous and dizygotic twins is 73% versus 23%, respectively.
Another method of studying atopic dermatitis is a genealogical one – in particular, the one based on of parental anamnesis. In this regard, we can mention the study conducted by Uehara and Kimura, which says that 60% of adults with this disease passed it down to their children.
Thus, several dozen independent clinical and statistical studies indirectly prove the genetic susceptibility of atopic diseases. All the diseases of this kind are associated with specific immune response to allergens (antigens).
Is it possible to assert that susceptibility is common not only to atopic diseases in general but also to atopic dermatitis in particular?
Despite the previously mentioned clinical studies, the question is still actual: can we conclude that atopic dermatitis has genetic foundations? Or maybe the fact that the skin becomes the main “target” of the disease is not determined by the specific manifestations of allergy in parents and previous generations?
In Uehara’s and Kimura’s research that we mentioned above (with 270 parents with atopic diseases involved in the study), the following pattern was revealed: if both parents had atopic dermatitis, the prevalence of the disease in children was 81%. The percentage decreased to 59% if the second parent was found to have not respiratory atopy, but dermatitis. When the second parent did not suffer from any atopic diseases, the percentage of children with atopic dermatitis was only 56%.
A study of the genetic explanation of atopy in schoolchildren conducted in 1992 showed that the odds ratio (OR) of atopic dermatitis was 3.4 in those schoolchildren whose parents suffered from one particular disease. If one of the parents suffered from another type of allergic disease, the OR of atopic dermatitis significantly decreased – to 1.5 for bronchial asthma and 1.4 for allergic rhinitis.
These particular studies, as well as dozens of other researches, let us suppose that there is a direct susceptibility not only to atopic diseases in general, but to atopic dermatitis in particular.
What is the practical value of the information concerning the inheritance of this disease?
What exactly can this information about the genetic susceptibility to atopic dermatitis give to a practicing pediatrician? It helps the doctor to:
- determine the risk of the development of the disease in children: such probability occurs when parents have any type of atopic diseases and it increases significantly if one or two parents suffer from atopic dermatitis. In both parents have it, the chances are very high.
- recommend appropriate preventive measures for children being at risk of developing atopic dermatitis, even if the symptoms of the disease have not been found. In this case, doctor will have an evidence base that will justify these recommendations.
- focus on the most effective treatment techniques of the disease based on knowledge of its molecular-genetic nature.