They studied more than 40,000 Swedish twins to determine the extent to which behavior, environment and genes each play a role in the development of chronic bronchitis. Hereditability accounted for 40 percent of the risk for chronic bronchitis, but, interestingly, 14 percent of the genetic risk was also linked to a genetic predisposition to smoke, whether or not the individual 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 survey included questions on zygosity—whether the twins shared 100 or 50 percent of their genetic material—smoking history and a checklist of common diseases. The interview asked specific screening questions designed to determine whether the interviewee had chronic bronchitis.
“[This] study on the population-based Swedish Twin Registry, showing a genetic effect for the development of chronic bronchitis that does not differ by sex is the first to our knowledge to quantify heritability of the disease,” said Jenny Hallberg, of the Department of Public Health Sciences at Karolinska Institutet in Stockholm. “Because chronic bronchitis had previously been reported to be more prevalent in women than men, the results pointed to a number of intriguing possibilities.
“It is possible that women are more prone to report symptoms,” remarked Hallberg. “Or, more likely, this could be an effect of smoking being more harmful for women due to their smaller lungs from start."
The investigators are currently working on a clinical follow-up study that is relating 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,” said Hallberg.
MEDICA.de; Source: American Thoracic Society