LONDON — A genetic variant commonly found in Chinese people may help explain why some got seriously ill with swine flu, a discovery that scientists say could help pinpoint why flu viruses hit some populations particularly hard and change how they are treated.
Less than 1 percent of Caucasians are thought to have the gene alteration, which has previously been linked to severe influenza. Yet about 25 percent of Chinese people have the gene variant, which is also common in Japanese and Korean people.
British and Chinese researchers analyzed 83 patients admitted to a Beijing hospital during the 2009-2010 swine flu pandemic. Of those with serious complications like pneumonia, respiratory or kidney failure, 69 percent had the genetic alteration. Among patients with mild illness, only 25 percent did.
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‘‘It doesn’t mean you should panic if you have this gene variant,’’ said Andrew McMichael, director of the Weatherall Institute of Molecular Medicine at Oxford University. ‘‘Most people who have it won’t run into any trouble at all.’’ He suggested people with this genetic predisposition to severe flu should be treated earlier and more aggressively than others.
McMichael estimated that people with the genetic variant were five to six times more likely to get severely ill once they are infected. The gene alteration does not make people more likely to catch the flu; that depends on other factors like environmental exposure and previous immunity.
McMichael said the gene variant might give people the same susceptibility to get severely ill from other ailments including dengue and SARS.