British and Chinese scientists have found a genetic variant which explains why Chinese populations may be more vulnerable to the H1N1 virus, commonly known as swine flu

The discovery of the genetic variant could help doctors find those people at high risk of severe flu and prioritize them for treatment, researchers said. It may also help explain why new strains of flu virus often emerge first in Asia, where the variant known as rs12252-C is more common in the population than elsewhere, they said. "Understanding why some people may be worse affected than others is crucial in improving our ability to manage flu epidemics and to prevent people dying from the virus," said Tao Dong at Britain's Oxford University, who led the study. The research found that having the rs12252-C variant could increase the chances of severe infection by six times. H1N1 swine flu swept around the world in 2009 and 2010. A study published recently estimated that at least one in five people worldwide were infected and around 200,000 killed in the first year of the outbreak, which was declared a pandemic by the World Health Organisation in June 2009. Previous research has found that rs12252-C is linked to more severe flu infections. For this study, researchers focused on the variant because it is 100 times more common in Han Chinese, the predominant ethnic group in China, than in white populations indigenous to West Asia and Europe. The variant is present in the genetic make-up of about 1 in 3,000 people in white populations. The results showed that it was present in 69% of Chinese patients with severe pandemic H1N1 in 2009 compared with 25% who only had a mild version of the infection.