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Childhood asthma genetic variant can be neutralized, say scientists

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Childhood asthma

A new study from the Ludwig-Maximilians-Universitaet (LMU) has discovered that the effect of a genetic variant that increases the likelihood of having childhood asthma can be neutralized.

The study was also able to show that young infants are benefiting to the positive effects of exposure to farm dust.

Asthma scientists from LMU in Munich have shown that specific environmental experiences and
influences can actually neutralize the effect of a prevalent genetic variant that poses a risk for the
development of childhood asthma. The same study was able to show that those that have this genetic
variant are also very responsive to environmental factors that are able to provide long term protection
against asthma. Children who had the genetic variant and were exposed to airborne microorganisms in
animal sheds before their first birthday were found to be more resistant to infections of the lower
respiratory tract as compared to those who had the genetic variant and hadn't been exposed to farm
animals in the early stages of their lives.

The study was conducted by Markus Ege, Professor of Pulmonary Epidemiology at Dr. Von Hauner's
Children's Hospital, together with Professor Erika von Mutius, Director of the Outpatient Clinic for Asthma
and Allergy, and first author Dr. Georg Loss, who is a member of von Mutius' team. It was published in the
American Journal of Respiratory and Critical Care Medicine. We can conclude from this observation that
these children are also less likely to develop asthma later on than carriers who did not benefit from the
˜farm effect', says Professor Ege.

The data was acquired from the long-term epidemiological study Pasture. They were in the form of
weekly diaries from around 1000 mothers who were recruited for the project and were residents in
predominantly rural regions. The mothers recorded details of the early development of their children
starting from birth and until the children reached 6 years of age. The diaries contained many information
including occurrences of respiratory illnesses and noted how much time the children spent in the farms.
When the researchers focused on the children that had a known genetic variant for asthma, which is
located on the q21 region of chromosome 17, they found out that carriers of the variant that were
exposed as infants for at least 2 hours a week to the air in animal sheds had an 80% drop in the occurrence
of wheezing, as compared to carriers of the variant in non-farm settings.

Childhood Asthma

Children who spend a lot of time with farm animals usually inhale small particles of hay and grass. Along
with these particles are many microorganisms such as bacteria, fungal cells and spores, as well as pollen
grains, which are carried into the airways. When these microorganisms reach the respiratory epithelium
that line the airways, they modulate the inflammatory response in the body. The ultimate goal of the
researchers is to discover what exactly causes this so-called farm effect, as this knowledge would truly
be helpful in developing new strategies that would be able to help prevent asthma. This is especially true
since having the genetic variant is not at all rare, which is estimated to be about 75% of the population.