Most of the kids also had moderate-to-severe asthma, not mild asthma, again indicating that their disease might have a strong genetic component. All were taking fairly high doses of inhaled steroids to help control their illness.
The analysis identified two genetic regions linked to asthma. One was the previously identified chromosome 17 locus, but there was also a newly spotted gene linked to asthma, called DENND1B, pinpointed on chromosome 1q31.
To make sure this wasn't a chance finding, the authors replicated the findings in groups of children in both the United States and Europe, including a group of black children.
"DENND1B is expressed most intensely on dendritic cells and on T lymphocytes [both key players in immune function]," Hakonarson explained. "Dendritic cells sit in the airway and take up any virus, allergen or any foreign culprit which is invading the airway and presents it to the T lymphocyte. Then the T lymphocyte determines what to do with the [invader]."
The T lymphocyte could then decide to ignore the invader, attack it or make a clone so the compound will be recognized again, in which case the person becomes sensitized to this particular compound.
Additional research not reported in this paper has revealed that the DENND1B gene regulates the release of cytokines -- key immune system signaling molecules.
"The level of cytokines probably has something to do with what [T lymphocytes] ultimately do -- ignore it, attack it or make a clone," Hakonarson said.
Now, researchers have "a truckload of work to do" to clarify the picture, he said.
And the whole picture, when ultimately revealed, is likely to be a complex one.
"It's not a surprise to find a confir
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