A genetic variant frequently found in Chinese populations may explain why severe
complications from swine flu are more common in China. The discovery may also have implications for other influenza virus strains and help
scientists understand why flu outbreaks hit some populations harder than others.
The variant is an alternative form - an allele - of a key
immune system gene. Chinese and British researchers looked for the variant in 83
patients admitted to a Beijing hospital during the 2009 and 2010 swine flu
pandemic. The allele was found in 22 of the 32 patients who suffered severe
complications from the virus but only 13 of the 51 patients with comparatively
The scientists calculated that the variant
increases the risk of developing a serious illness by five to six times once a
person is already infected. The allele is found in around a quarter of Han
Chinese, the largest ethnic group in China. It is also common among Japanese
and Korean populations but found in only one in 3,000 caucasians.
'It doesn't mean you should panic if you have this gene
variant', said Professor
Sir Andrew McMichael, director of the Weatherall Institute of Molecular
Medicine at the University of Oxford and one of the study's authors. 'Most people who
have it won't run into any trouble at all'.
Previous research has shown that the variant — called rs12252-C
— is associated with more severe disease for other kinds of flu. Although it doesn't make people more likely to catch the flu, it could help
explain why new strains of the virus often emerge first in Asia. Swine flu
swept around the world in 2009, infecting an estimated one in
five people worldwide. Around 200,000 people died in the first year of the
The latest results may lend support to the idea that genetic screening should eventually be included in national flu plans in order to
better assess people at greatest risk of severe infection. Professor Peter
Openshaw, director of the Centre for Respiratory Infection at Imperial
College London, who was not involved in the study, told
Associated Press: ' Further work needs to be done to justify that, but
maybe in the future we would be able to say that if you're of a certain
ethnicity, you are more at risk and should be prioritised for vaccination or
However, he added: 'It's possible we could one
day do a genetic test before treating someone with flu to see what the best
treatment would be'.
The study was published in Nature Communications.