WEDNESDAY, April 9 (HealthDay News) -- Just a small change in one gene, called CHI3L1, can increase a person's risk of developing asthma.
The genetic variation in CHI3L1 causes the gene to release high levels of a protein known as YKL-40, and high levels of this protein have been associated with an increased risk of asthma in past research. The current study found that high levels of YKL-40 in four different population groups were linked to the development of asthma in all four groups, suggesting that YKL-40 and CHI3L1 are likely at the root of some cases of asthma.
That means if scientists can block YKL-40, they could create a novel, potentially more effective treatment for people with asthma.
"While there won't be one silver bullet for all asthma, we can start to think about tailoring medications to get at the cause, rather than just alleviating asthma symptoms," said study author Carole Ober, a professor of human genetics at the University of Chicago. "These findings give us optimism that one day there will be better treatments, more targeted to the specific cause of asthma."
The findings were published online April 9 by the New England Journal of Medicine and were expected to be in the journal's April 17 print issue.
It's believed that YKL-40 was originally produced by the body as a defensive mechanism against harmful parasitic worms, called helminths, according to Dr. Burton Dickey, chairman of pulmonary medicine at M.D. Anderson Cancer Center in Houston. Dickey said that helminths contained a substance called chitin that is also found in fungi, crustaceans and in insects such as dust mites and cockroaches. YKL-40 is what's known as a chitinase-like protein, because it attaches itself to chitin, possibly alerting the body that chitins are present.
But, Dickey pointed out that in the developed world, chitin infections simply aren't an issue any longer, so now this defense mechanism may be reacting to chitin in harmless settings.
In November 2007, Yale researchers reported that people with severe asthma had higher levels of YKL-40. This finding led to the current study, which measured levels of YKL-40 in an isolated population called the Hutterites. The Hutterites settled their isolated religious community in South Dakota in 1874. They live communally, share the same food, have the same education and socioeconomic status. About 11 percent of Hutterites have asthma, and 12 percent have hyperactive airways.
Working with the Yale team, Ober found that the Hutterites with asthma or overactive airways had elevated levels of YKL-40. After searching their genetic code, Ober and her colleagues found that one tiny change in the CHI3L1 gene was slightly different in Hutterites with asthma. When the researchers compared these findings to three different groups of people from Chicago; Madison, Wisc.; and Freiberg, Germany, they found an association with changes in CHI3L1 and YKL-40 levels, and the development of asthma. Some children were too young to have developed asthma, but already showed higher levels of YKL-40 if they had the genetic change.
Ober said that not everyone with high levels of YKL-40 develops asthma, but that someone with the CHI3L1 change inherited from both parents "was twice as likely to develop asthma as someone who doesn't have it."
"YKL-40 seems to be involved in many different diseases in which inflammation is a component, and so it is likely to be an important component of the innate immune response, and treatments directed at YKL-40 may be helpful in all of these diseases," said Dr. William Cookson, co-author of an accompanying editorial and a professor of respiratory genetics at the National Heart and Lung Institute at Imperial College in London.
Dickey said the Yale team is currently working on an animal model that doesn't produce YKL-40 to see if the protein is important in other functions in the body.
"If the protein doesn't contribute importantly to any other biological process, it's likely just involved as a parasitic defense, and inhibiting it may not cause any problems, yet could provide substantial benefit [in terms of asthma treatment]," said Dickey.
More information
To learn more about the causes of asthma, visit the National Heart, Lung, and Blood Institute.
MONDAY, April 7 (HealthDay News) -- Researchers have identified a probable case of human-to-human transmission of bird flu in China.
The finding lends credence to the idea that there's a genetic component to human-to-human transmission of this potentially dangerous virus, a new study reported.
"This suggests that there's some genetic component to resistance in the person who's infected," said Philip Alcabes, an epidemiologist and associate professor at the School of Health Sciences of Hunter College in New York City.
The finding follows reports of probable human-to-human transmission of the H5N1 bird flu virus in Pakistan.
A person's ability to monitor foreign microscopic invaders such as avian virus is essentially genetic, Alcabes said. "That may account for why certain families seem to be susceptible whereas most people aren't," he added.
According to background information for the new study, published online Tuesday in The Lancet, there have been 376 reported cases of infection with avian H5N1 virus around the world as of April 2, with 238 deaths since November 2003.
The H5N1 virus has infected poultry throughout Southeast Asia, Central Asia, Africa and Europe, prompting the destruction of millions of birds. The concern among health officials is that the virus will mutate and acquire the ability to jump easily between humans, leading to a pandemic and millions of deaths. Unlike the seasonal flu, humans have no immunity to bird flu.
In December 2007, according to the Lancet report, a father and son in Nanjing, China were diagnosed within one week of each other as being infected with H5N1. Researchers from the Chinese Centre for Disease Control and Prevention in Beijing conducted field and laboratory tests of both men, as well as 91 people who had had close contact with them.
It seems that the 24-year-old son, who died, was exposed to H5N1 when visiting a poultry market six days before he fell ill. The 52-year-old father, who survived, had had substantial contact with his son while caring for him in the hospital. The father had no known direct exposure to birds or other sick individuals.
The H5N1 viruses sampled from the father and the son were virtually genetically identical.
The father received antiviral treatment as well as plasma from an individual who had been vaccinated against the virus as part of a vaccine trial. The son was diagnosed too late to receive appropriate treatment.
All 91 exposed contacts, including the son's girlfriend and mother, tested negative for H5N1.
Transmission may have occurred if the father inhaled droplets coughed out by his son, or by contact with the son's clothing that was contaminated with fecal matter. The father wore a surgical mask during his last visit with his son but had not worn protective gear before that, the report stated.
Interestingly, no outbreaks of H5N1 in poultry were identified in Nanjing, a city in eastern China, before or after these two human cases. No sick or dead poultry were seen either, the report said, adding that it's also important to note that this case of son-to-father transmission has not been proven yet.
According to the study authors, more than 90 percent of H5N1 clusters in humans have occurred in blood-related family members.
And, experts said, this latest case is no reason for alarm.
Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, which funded the study, said, "This is not something new. Limited human-to-human transmission has been seen intermittently for years and years. This is just another example among a few. It's what we call a dead-end person-to-person transmission."
He added, "What we worry about is secondary and tertiary transmissions, when someone gives it to someone who gives it to someone. That is not the case here."
"I took great reassurance from this study," Alcabes added. "Very, very occasionally, you can get limited transmission of the avian virus from one infected human to another human, but it seems only to happen in families. There's nothing here to suggest new reasons to worry, let alone panic."
Added Dr. Pascal James Imperato, chairman of the department of preventive medicine and community health at SUNY Downstate Medical Center in New York City, "There's no proof positive that the father was not independently exposed to poultry."
The Pakistan case involved a poultry worker who became infected and survived last year, while three of his brothers were also infected, and two died, according to a BBC News report on Saturday.
Genetic-sequencing tests on bird flu virus samples collected from three of the four brothers confirmed human-to-human transmission of the H5N1 virus, the World Health Organization reported.
The northwestern region of Pakistan has 85 percent of the country's poultry farms and was one of the regions hardest hit by bird flu last year BBC News noted.
More information
The World Health Organization 
has more on avian flu.