Mould may trigger severe asthma

Living in a home with high levels of mould may increase the risk of severe asthma attacks in people with certain gene variants, finds a new study.

"We found that the interaction between environmental mould exposure and certain variants of chitinase genes were positively associated with severe asthma exacerbations requiring hospitalisation," lead researcher Ann Wu, an assistant professor at Harvard Medical School and Harvard Pilgrim Health Care Institute, said.

Chitinases, which break down a component in fungi called chitin, are induced during allergic inflammation. It's known that people with asthma have higher expression of certain variants of chitinase.

The study

In this study, Wu and colleagues analysed data from the Childhood Asthma Management Program, a trial that enrolled children between the ages of five and 12 with mild to moderate persistent asthma. The children's homes were classified as having more or less than 25 000 mould colonies per gram of household dust. A level greater than 25 000 is considered high for a home.

The researchers also conducted genetic tests on blood samples taken from the children. They concluded that certain variants of the chitinase gene CHIT1, along with exposure to high levels of mould, are associated with an increased risk of severe asthma attacks.

The study, published online and in an upcoming print issue of the American Journal of Respiratory and Critical Care Medicine, suggests that chitinases may offer a target for new types of asthma treatments. - (HealthDay News, June 2010)

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