The researchers found that 90 percent of children under age 3 who wheezed after catching a cold and had the genetic marker, which is a DNA sequence associated with a particular gene, developed asthma by the time they turned 6.
"We're pretty excited about it. One of the most important findings in the study is that now we have a genetic marker that helps us identify those children with the highest risk of developing asthma," said co-senior author Carole Ober, a professor of human genetics at the U. of C. "In the first three years of life, one-third of children who get sick and wheeze go on to develop asthma. Now we have a genetic marker to potentially help differentiate between transient and persistent wheezers."
Researchers from the University of Wisconsin at Madison and from Copenhagen, Denmark, also participated in the study, which was published April 11 in the New England Journal of Medicine.
One-quarter of the children who participated had two copies of the genetic marker, and 50 percent had one copy.
Those children who had two copies of the genetic marker were almost four times as likely to develop asthma as children who did not wheeze when they caught a cold and do not have the genetic marker, the researchers said.
"We think the same gene is related to how many wheezing illnesses a baby gets, and we think the gene is also determining how the baby recovers from wheezing illnesses and how lung cells repair themselves, or clear themselves of the virus," Ober said.
The researchers' next steps include trying to understand how this particular gene works in lung cells, Ober said.
Dr. Fernando D. Martinez, director of the BIO5 Institute and of the Arizona Respiratory Center and a professor of pediatrics at the University of Arizona, called the paper "a very well-done, very important study."
"It really changes the way we think about the way we have to study these complex diseases in the future, in an integrated way, to really understand them," Martinez said.