SCOTTISH researchers believe they have made a significant medical breakthrough by identifying a genetic defect which can triple the risk of a child developing an allergy to peanuts.
The gene responsible - filaggrin - is found in human skin and had previously been shown by scientists at Dundee University to be a significant factor in causing eczema and asthma.
They have now found that one in five of all peanut allergy sufferers also have a filaggrin defect.
Dr Sara Brown, the Dundee-based scientist who led the international study involving researchers in Canada, Ireland, England, and the Netherlands, said yesterday that the discovery marked a "significant breakthrough" in understanding the causes of an allergic condition which has increased dramatically over the past 30 years.
At least one in every 100 children in the UK suffer from the potentially life-threatening allergy which can cause symptoms ranging from a mild stomach upset to a fatal anaphylactic reaction.
Dr Brown, the Wellcome Trust intermediate clinical fellow in molecular medicine at Dundee, said: "We know that peanut allergy runs really strongly in families. Now, for the first time, we have a genetic change that can be firmly linked to peanut allergy."
Having shown that filaggrin was a significant factor in causing eczema and asthma, the research team decided it was a "logical next step" to investigate whether the gene might also be a cause of peanut allergy.
"A child may develop all three of these diseases together," Dr Brown said. "Allergic conditions often run in families, which tells us that inherited genetic factors are important. In addition, 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."
According to the study, a fifth of all peanut allergy sufferers have a filaggrin defect. Those with the defect can be three times more likely to suffer peanut allergy than people with normal filaggrin.
Dr Brown said: "There are lots of children who have a filaggrin defect and don't get a peanut allergy. So it's not as simple as saying that a filaggrin defect causes peanut allergy in those children - there are obviously other things going on as well. But in those children who have a peanut allergy, it would be a significant contributing factor."
She added: "We are a little way off doing screening test. But what it paves the way for is a better understanding of the skin's importance and a clearer understanding that we need to develop treatments to improve filaggrin in the skin.
"We are now working on treatments to improve the amount of filaggrin protein in our lab. And if those treatments become widely available then we would hope that they would reduce the number of children with peanut allergies."A spokeswoman for Allergy UK said: "This is a very important discovery and an exciting step towards increasing our understanding of peanut allergy, although as highlighted by the researchers in Dundee this will not apply to all peanut allergy sufferers and there is more work to be taken forward."