Peanut allergy gene discovery could lead to early diagnosis
Canadian researchers have identified a gene associated with the allergy to peanuts that could prove to be a useful target for predicting and treating food allergies.
The gene — called c11orf30/ EMSY — appears to play an important role in a variety of allergic responses to peanuts and other foods.
“The discovery of this genetic link gives us a fuller picture of the causes for food allergies and this could eventually help doctors identify children at risk,” said coauthor Denise Daley, a professor at the University of B.C.
That will be a huge relief for worried parents.
“If there had been a test (for nut allergies), armed with that knowledge, life would have been much better,” said Shahee Lakhani, whose 13-year-old son Nurain is allergic to tree nuts and peanuts. “If I had known, I would have been mentally prepared and I would not have exposed him to harm.”
When her son was 18 months old, Lakhani triggered Nurain’s first reaction when she gave him a quarter of a cashew while shopping, completely unaware of his condition.
“I only found out about his allergy when I almost killed him,” she said.
“Had I known, of course I would have done things so differently.”
Nurain has had anaphylaxis — a potentially fatal allergic reaction — five times in the past three years, including incidents at a cruise ship buffet and a birthday party.
“The mother, who is so careful, was absolutely devastated that this happened,” Daley said. “These are accidents, but it’s very stressful. Now he’s a teenage boy with a teenage brain.”
In the study, five additional genetic locations were identified that appear to be involved in how and even whether a person becomes allergic to peanuts, through a process called epigenetics.
Epigenetics is the study of how life events such as exposure to certain substances or pathogens can turn genes on and off like a light switch, sometimes triggering — or curtailing — genetic disease.
“This is important, because we already know from a clinical trial a couple of years ago, peanut allergy can be dramatically reduced through early exposure to peanuts,” said Daley.
The new finding comes as the medical community is overhauling the advice being given to new parents to counter a rising tide of peanut allergy in children, which appears to have risen fourfold in less than two decades. In 1999, peanut allergy was estimated to affect 0.4 per cent of children in the United States, but by 2010 that figure had risen to two per cent of all children. A study by McGill University — also released in 2010 — found that 1.93 per cent of Canadian children have a peanut allergy.
Exposure to peanuts well before the first birthday dramatically reduces the chances of allergic reaction, but cautious parents heeding the misguided advice of some doctors are delaying giving their babies peanuts.
Unless they are known to have pre-existing food allergies or eczema, feeding peanuts to babies between four and eight months of age is the best way to prevent an allergy to peanut, according to Dr. Edmond Chan, director of the allergy clinic at B.C. Children’s Hospital. Introducing peanuts early “trains” the immune system to recognize that the unique proteins it contains are not dangerous invaders.
Unfortunately, about 80 per cent of Canadian physicians counsel parents to delay introducing peanut until 12 months, Chan said.
Daley is hopeful the new genetic findings will also lead to advances in understanding a whole range of related diseases, such as asthma and eczema.
“About 80 per cent of people with asthma also have eczema, hay fever or food allergies,” she said. “You see babies presenting with eczema at three to six months and within a year those same babies will get a wheeze and then food allergies and full-blown allergic disease.”
The findings were published on Tuesday in the Journal of Allergy and Clinical Immunology.