Peanut allergy has a genetic link: Study

By Dr. Ananya Mandal, MDMar 14 2011

A new study suggests that children with a certain gene defect are more likely to develop a peanut allergy. They studied the effect of changes in the gene filaggrin, which helps the skin block out allergens. They noted what has been seen before – the changes in the gene reduce the effectiveness of the barrier, increasing the risk for eczema and asthma.

The U.K., Dutch and Canadian the researchers now find that such changes appear to raise the risk of peanut allergy as well. Their study was published in the March 2011 issue of the Journal of Allergy and Clinical Immunology. ," Dr. Sara Brown of the division of molecular medicine at the University of Dundee said, “It was a logical next step to investigate whether filaggrin may also be a cause of peanut allergy, since a child may develop all three of these diseases together…Allergic conditions often run in families, which tells us that inherited genetic factors are important. In addition to that, changes in the environment and our exposure to peanuts are thought to have been responsible for the recent increase in peanut allergy seen in the Western world in particular.”

The team’s findings suggest one in five peanut allergy sufferers has a filaggrin defect, which means it is not the only cause of peanut allergies, said Prof. Irwin McLean, a study co-author also based at Dundee in Scotland. The people with this defect are three times more likely to suffer a peanut allergy than people with normal filaggrin, the researchers reported.

For the study they involved 71 English, Dutch, and Irish patients with positive peanut results in an oral food test, where the patient eats the food while a physician watches carefully for symptoms. Their genetic findings were compared with 1,000 controls from the English population. The investigation was then repeated in 309 Canadians with peanut allergies and another 891 controls from the general Canadian population. Authors concluded, “Taken together, our experimental data from four populations of European origin demonstrate a strong and significant association of loss-of-function mutations within the filaggrin gene with clinically significant peanut allergy.” It is estimated about one in 50 Canadian children has a peanut allergy, and about one to two per cent of these can have severe or life-threatening reactions, according to Anaphylaxis Canada.

The Canadian peanut allergy study was supported by grants from the Canadian Dermatology Foundation, the University of Saskatchewan, Department of Medicine Research Fund, the Foundations of the McGill University Health Centre and the Montreal Children's Hospital as well as grants from the Canadian Allergy, Asthma, and Immunology Foundation and the AllerGen Network of Centres of Excellence.