Study Suggests Genetic Factors in Smoking may Increase Risk of Chronic Bronchitis

Expert Rev Resp Med. 2008;2(2):145-147. 

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While smoking is the leading risk factor for chronic bronchitis, genes also play a major role in the development of the disease, a recent Swedish study reports.

A recent study, published in the first issue for March of the American Journal of Respiratory and Critical Care Medicine, highlights the importance of genes in the development of smoking-related respiratory diseases, such as chronic bronchitis.

The study, which analyzed data on more than 40,000 Swedish twins born in 1958 or earlier, found that inherited genes accounted for 40% of the risk for chronic bronchitis and that 14% of the genetic risk was also linked to a genetic predisposition to smoke, whether or not a person actually smoked.

The researchers analyzed data from the Screening Across Lifespan Twin (SALT) study in Sweden, which surveyed all known living twins in Sweden born in 1958 or earlier. The investigators used the survey data and statistical modeling to determine the extent to which the genetic and environmental influences that comprise an individual's risk of developing chronic bronchitis were responsible for disease progression.

"...inherited genes accounted for 40% of the risk for chronic bronchitis..."

Jenny Hallberg of the Department of Public Health Sciences at the Karolinska Institutet, Stockholm, cautioned that the finding that the genetic factors contributing to chronic bronchitis were largely independent of those that contribute to smoking should not be interpreted to mean that smoking has no effect on chronic bronchitis. "Although there was some genetic interplay, it is safe to say that smoking itself, and not the genes that predispose one to smoking, is a larger risk factor in developing chronic bronchitis of environmental exposures primarily smoking than genetic predisposition. This is true in both men and women," said Hallberg.

The research team is currently working on a clinical follow-up study that relates clinical measures of lung function to obstruction. "We believe that it is important to also include testing of lung function to disentangle whether there are genetic differences by sex," stated Hallberg. "There is also data in the literature that social factors have different importance for smoking behavior in men and women. We know much less regarding the genetic influences."

Source: Hallberg J, Dominicus A, Eriksson UK et al. Interaction between smoking and genetic factors in the development of chronic bronchitis. Am. J. Respir. Crit. Care Med. 177, 486-490 (2008).


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