It's not just genes, environmental exposure too determines if a person would develop asthma, says a leading expert.
Dr. Fernando D. Martinez, director of Arizona Respiratory Center, said that 39 potential "asthma genes" have already been identified.
But, for nearly every gene found to be negatively associated with asthma in one study, other studies have failed to replicate the findings.
"This suggests that the effect of these genes on allergic diseases is not direct and simple. Many genetic variants associated with asthma will not increase the risk of the disease in all persons. Most will modulate the effects of environmental exposures, making certain subjects more or less susceptible," he said.
With respect to environmental exposures worsening asthma, Martinez highlights viral infections, passive smoking and air pollution.
But the impact of all environmental factors is not necessarily obvious, as some exposures play a protective role.
"For example, in farming communities where exposure to microbial products is high, children have significantly less asthma and allergies," said Martinez.
In some cases, an allele (part of a gene) found to be a higher risk factor for allergic asthma in some individuals might be associated with less risk of developing asthma in others.
Martinez has pinpointed the CD14 gene as one such example, saying that when people with a variant of this gene are exposed to high levels of endotoxin (a product present in bacteria), it protects them from developing an allergic response.
But people with this same gene variant who are exposed to low levels of endotoxin are at higher risk of an allergy.
Research is going on to identify and understand the genes related to asthma.
"We have identified many genetic variants associated with asthma and allergies. However, only a fraction of the variants have been discovered. A lot of work still needs to be done to uncover how these diseases are inherited," said Marteniz.
Martinez suggests that the expectation that doctors will someday be able to predict asthma at birth should be replaced with an expectation that experts will be able to identify which children should or should not be exposed to certain environmental factors to lessen their risk of developing asthma.
"The hope is that by combining information on genetic markers and exposures, we will be able to identify even more accurately children at high-risk for different forms of asthma in the future," he said.
Saturday, November 7, 2009
Both genetics and environmental factors determine asthma risk
Sunday, April 19, 2009
Thirsty Camels 'turning the taps on' in central Australia
Camels are coming into communities in central Australia and turning on the taps, the Macdonnell Shire Council says.
The shire has applied to the Federal Government for a $4.5 million slice of infrastructure funding to build camel-proof boundaries around 14 communities.
Wayne Wright from the shire says thirsty camels are causing significant damage.
"In a number of our communities it's quite common for camels to enter the community and if there are any taps adjacent to houses they're quite capable of either turning the taps on or knocking the taps off so they get water."
The intention is to put cattle grids at the entrances of the communities and place fencing around them.
The fencing would also protect the communities from other feral animals, such as donkeys and horses.
Mr Wright says the animals rip up plants and thwart efforts to improve the aesthetics of the communities.
"The big issue for us is should we try to do any beautification works in our communities - tree planting, grassing of areas.
"Unless we can limit the access to those areas, we are going to be wasting our money."
The shire is expecting to find out if the application has been successful next month.
Klik disini untuk melanjutkan »»
