Abstract
Background: We studied the relative influence of genetic and environmental factors on the variation in susceptibility to chronic bronchitis.
Methods: In a population-based questionnaire study of 13,649 twins, 50-71 years of age, from the Danish Twin Registry, we calculated the sex-specific concordance rates and heritability of chronic bronchitis.
Results: The prevalence of CB was 9.3% in men and 8.5% in women. The concordance rate for chronic bronchitis was higher in monozygotic twins than in dizygotic twins among women; 0.30 vs. 0.17, but not among men; 0.15 vs. 0.18. The heritability of chronic bronchitis adjusted for smoking and age was 50% (30-67%) in women, whereas familial aggregation of chronic bronchitis in men was ascribable to 25% (8-41%) familial environment but not to genetic factors.
Conclusions: Chronic bronchitis shows moderate familial aggregation, particularly in women. Increased respiratory morbidity and mortality among female smokers relative to male smokers may have a genetic origin.
- © 2011 ERS