Peanut allergy may begin in the genes, study shows

On a recent day, 21/2-year-old Connor was busy helping his grandmother make cookies, a normal family scene except for what happened before the bowls and measuring spoons came out.

Connor's mother, Rachel Kasprik, and his grandmother had to research a recipe without milk and peanuts and meticulously scan labels on the ingredients because the Bethesda toddler has food allergies.


Up to 10 percent of U.S. children have a food allergy, a large and growing number that experts struggle to explain. But researchers at the Johns Hopkins University now have a clue: A new study suggests some people have a genetic predisposition.

"The information could eventually help us to predict which child would be at risk of a food allergy and help us figure out what environmental modifications may stop the progression of disease," said Dr. Xiaobin Wang, study's principal investigator.


Researchers long suspected a genetic link to food allergies, and that is supported by this study, the first allergy study to analyze the entire human genome, said Wang, a professor and director of the Center on the Early Life Origins of Disease in the Hopkins Bloomberg School of Public Health.

For the gene study, they scanned the genomes of almost 2,760 people, including children and their parents who mostly had a food allergy.

They were able to identify the region harboring genes linked specifically to peanuts — a particular problem, as the number of children with such an allergy doubled in the last 10 years. It's also typically a lifelong allergy, unlike other common allergens including milk and eggs, which kids typically outgrow.

This new genetic information means doctors may be able to tell, perhaps in the womb, who might develop a peanut allergy, according to the findings, published online in the journal Nature Communications.

But not everyone with the genes becomes allergic to peanuts, researchers found. They believe this is because the genes' DNA hasn't changed, but the environment is influencing the genes to act differently.

Wang said that means development of a peanut allergy isn't as simple as specific gene mutations that cause disease such as cystic fibrosis or Huntington's. But it also means that the changes may be reversible because they are set in the code, she said.

"Maybe we interrupt the pathway somehow," said Wang, which could lead to new avenues for prevention or treatment. If possible, that's a ways off, she acknowledges.

For now, researchers are working on another promising avenue of treatment for peanut allergies — offering tiny amounts of peanut in increasing amounts, in an attempt to develop tolerance. There is a patch form and, at Hopkins, a powder form.

The idea has shown promise in adults and older children. It's the same idea as allergy shots, offered for decades to those with allergies to animals, mold, pollen and other environmental elements.

Connor joined a three-year study last fall that uses powder after Kasprik went looking for a study. Once a researcher herself, she recognized the promise of human trials. Even if Connor wouldn't directly benefit, maybe other children would.

Still, she hoped the method would help Connor's body cope with peanuts. For now, the family must continue to cope with a complex allergy, which could give him a range of reactions, a terrifying prospect for his parents.

The family rarely eats out and doesn't fly on vacation. Kasprik also reads labels, calls manufacturers and takes precautions in public places, such as wiping down playground equipment and shopping carts and carrying quick-acting allergy medications.


At his last birthday, they bought grocery store cupcakes billed as allergy-free, but they tasted so bad no one ate them. By this Easter, they substituted toy trucks for candy.

Kasprik discovered he was allergic to milk one day when Connor was about 6 months old and launched his face into an ice cream cone she was eating. He broke out in hives. The same thing happened when a dog rubbed against his face.

She took him to an allergist who discovered his potentially more dangerous peanut allergy.

Kasprik has since discovered that several neighbors also have children with food allergies.

"Even if Connor gets no benefit from his study, it would be great if they figure out treatment for others," she said. "If they figure out the gene part and eliminate the allergy completely, that would be even better."

For now, definitive preventive measures are elusive, said Dr. Robert Wood, chief of the division of allergy and immunology for Hopkins Children's Center. He is overseeing Connor's study and also participated in the gene investigation.

He said mothers cannot prevent the allergy by eating a lot of peanuts while pregnant or breast feeding. The allergy typically shows up in the first two years, mostly when the child consumes the food for the first time.

He's hoping his study will show that children can become desensitized, though the treatment may require that people continue to eat peanuts regularly to avoid developing allergic reactions again later in life.

So far, however, only a few hundred people around the world have participated in studies, and they were mostly adults. Previous attempts to develop tolerance through shots failed, Wood said, when people had severe reactions because doses were too high.

He also pointed to another study published recently in the New England Journal of Medicine that holds promise, called the LEAP study, for Learning Early About Peanut Allergy.

It found infants at risk for allergies, perhaps because of a family history, may be able to avoid developing reactions by eating peanuts at least three times a week beginning by 11 months old. Among children in the study, about 17 percent who avoided peanuts developed an allergy by age 5, but only 3 percent who ate peanuts regularly developed an allergy.

This means doctors can now tell parents not to avoid peanuts so long as there isn't a known allergy, said Dr. James R. Baker, CEO of Food Allergy Research & Education, or FARE, an education and support group that helped fund the genetic and LEAP studies.

Baker, a professor at the University of Michigan and an allergist for 32 years, said the rise in peanut allergies is startling. He said one explanation is that children don't get infected as they once did because of vaccines and antibiotics, and the immune system has gotten off kilter. He said there likely are environmental factors too.

But all the research makes him hopeful for new treatments and preventive measures.

"My true hope is that we're able to get food therapies that are FDA-approved that everyone can use," Baker said. "There just aren't any now."

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