A study just published on bmj.com concludes that the defects in a particular gene known as the filaggrin gene are linked to a considerably amplified risk of developing allergic disorders such as eczema, rhinitis, and asthma.
Over the past years, allergic diseases have increased. In economically developed countries, those diseases now affect up to one in three children. For a long time researchers have looked for genes that might contribute to allergic diseases. Until now, no important links had been discovered and the concept of a real “allergy gene” was vague.
But new information has been constantly indicating that there is a strong influence of the filaggrin gene in maintaining an effective skin barrier against the environment.
In order to find out more, the results of 24 studies were analyzed by researchers at the University of Edinburgh. They investigated if filaggrin gene mutations increase the risk of developing allergic sensitization and allergic disorders.
In order to maintain objectivity, the differences in study quality were identified and taken into account.
After merging the results, it was apparent that filaggrin gene mutations significantly increase the risk of developing allergic sensitization, atopic eczema, allergic rhinitis, and asthma in people with eczema. The association between filaggrin gene mutations and atopic eczema was particularly strong.
Filaggrin gene mutations also amplified the risk of asthma in people with atopic eczema.
The authors explain: “These findings provide strong supporting evidence that, at least in a subset of those with allergic problems, the filaggrin gene defect may be the fundamental predisposing factor not only for the development of eczema but also for initial sensitization and progression of allergic disease.”
They write: “Our finding suggest that filaggrin is a robust biomarker for allergic conditions.”
There is a need for further studies to investigate whether filaggrin can be used to identify individuals that are at high risk. They conclude that restoring skin barrier function in filaggrin deficient people in early life may also help prevent the development of sensitization and stop the development and progression of allergic disease.
In an associated editorial, experts from Singapore say: “This study represents an important breakthrough in understanding the genetic basis of this complex disorder.” They finish by saying: “The next challenge will be to distinguish different genotypes of allergy, which could revolutionize the prevention, diagnosis, and treatment of allergy in children.”
“Filaggrin gene defects and risk of developing allergic sensitisation and allergic disorders: systematic review and meta-analysis”
Rosanne A HMvan den Oord, Socrates research student Aziz Sheikh, professor of primary care research and development
BMJ 2009; 339:b2433
“Gene defects and allergy”
Hugo Van Beve ,professor and head of paediatric allergy, immunology, and rheumatology division, Birgit Lane ,executive director and principal investigator, John Common, senior research fellow.
doi=10.1136/bmj.b1203
Written by Stephanie Brunner (B.A.)