Certain genetic factors and wheezing early in
life are associated with a greatly increased risk of asthma in children, a new
Researchers examined data from nearly 500
children and found that about 90% of those who had two copies of a common
genetic variation and who also experienced wheezing when they had a cold early
in life developed asthma by age 6.
These children, all from families with a history
of asthma or allergies, were nearly four times more likely to develop asthma
than those who did not have the genetic variation and did not wheeze, according
The genetic variation is found on chromosome 17
and is common. Half of the children in the study had one copy and 25% had two
copies. The researchers also noted that colds are extremely common and affect
nearly all infants.
The increased risk is associated with wheezing
during colds caused by a human rhinovirus infection, the University of Chicago
Medical Center researchers said.
"We found that the interaction between this
specific wheezing illness and a gene or genes on a region of chromosome 17
determines childhood asthma risk," study author Carole Ober, a professor of
human genetics at the University of Chicago, said in a medical center news
"The combination of genetic predisposition and
the child's response to this infection has a huge effect."
The researchers said it is not clear how this
gene variation and wheezing interact to increase the risk of developing asthma.
It also should be noted that the research showed only an association between
them, and not a cause-and-effect relationship.
About 25% of children who had no wheezing from a
human rhinovirus infection developed asthma, and 40% of those who experienced
wheezing in the first three years of life but lacked the risk-related gene
variants developed asthma.
That rose to nearly 60% among those with one copy
of the gene variant and to 90% for those with two copies.
The American Lung Association has
more about children and asthma.
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