Household mould may trigger severe asthma attack

Mould in homes may trigger severs athma attacks Linked to variations in chitinase genes

Living in a home which has mould may increase the risk of a severe asthma attack, new research suggests.

A study by Harvard Medical School found that people who had certain variations in the chitinase gene were more susceptible to high levels of fungus and more likely to require hospitalisation due to asthma.

Chitinases are enzymes which break down chitin, a component in many fungi and are induced during allergic inflammation. Past research has shown that variant chitinase genes are more active in people with asthma.

In the study, the researchers analysed data from the Childhood Asthma Management Program, a trial that enrolled children between the ages of 5 and 12 with mild to moderate persistent asthma.

The children's homes were tested for the amount of mould present at the start of the study. Homes were classified as having greater or less than 25,000 mould colonies per gram of household dust.

The researchers also looked for genetic variations in the chitinanse genes in blood samples taken from the children.

When they compared the two, they found that certain variants of a chitinase gene CHIT1, in conjunction with exposure to high levels of mould high increased the risk of severe asthma attacks.

Dr Ann Wu, assistant professor at Harvard Medical School and Harvard Pilgrim Health Care Institute said: "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 mould, but there is no specific level that is currently accepted to "cause" problems."

Dr Wu also added that treatment designed to block chitinase enzyme activity may be an option in the future.

The research was published online on the American Thoracic Society's journal Web site ahead of the print edition of the American Journal of Respiratory and Critical Care Medicine.

This article was published on Fri 25 June 2010

Image © RomainQuéré -

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