"We found that the interaction between environmental mold exposure and certain variants of chitinase genes were positively associated with severe asthma exacerbations requiring hospitalization," said lead researcher, Ann Wu, assistant professor at the at Harvard Medical School and Harvard Pilgrim Health Care Institute.
In the study, mold measures were taken in the subjects' homes at the beginning of the study, and homes were classified as having greater or less than 25,000 mold colonies per gram of household dust.
"This level of mold in dust is high for a residential environment. However, it is not likely to be easily recognized. Studies have shown that homes that have problems with dampness (e.g. visible mold on walls/ceilings, water collection in basement, etc.) have higher levels of mold, but there is no specific level that is currently accepted to 'cause' problems," said Dr. Wu.
They found that certain variants of the chitinase gene CHIT1, in conjunction with high mold exposure, were associated with increased risk of severe asthma attacks.
It is plausible, Wu said, that therapeutics designed to block chitinase enzyme activity might prevent hyper-responsiveness and inflammation related to asthma.
The article is published in American Journal of Respiratory and Critical Care Medicine.