title: Twins studies as a model for studies on the interaction between smoking and genetic factors in the development of chronic bronchitis.
abstract: Smoking is the main risk factor for COPD (chronic obstructive pulmonary disease) but genetic factors are of importance, since only a subset of smokers develops the disease. Sex differences have been suggested both in disease prevalence and response to environmental exposures. Furthermore, it has been shown that acquisition of 'addiction' to smoking is partly genetically mediated. Disease cases and smoking habits were identified in 44919 twins aged >40 years from the Swedish Twin Registry. Disease was defined as self-reported chronic bronchitis or emphysema, or recurrent cough with phlegm. The results showed that chronic bronchitis seems to be more prevalent among females, and that the heritability estimate for chronic bronchitis was a moderate 40% and only 14% of the genetic influences were shared by smoking. In addition, 392 twins have been invited to a clinical investigation to evaluate: (i) to what extent genetic factors contribute to individual differences (variation) in FEV(1) (forced expiratory volume in 1 s), vital capacity and DL(CO) (diffusion capacity), taking sex into consideration, and (ii) whether smoking behaviour and respiratory symptoms influence these estimates.
authors.affiliation: Department of Public Health Science, Karolinska Institutet at Norrbacka, SE-171 76 Stockholm, Sweden. magnus.svartengren@ki.se
authors.forename: Magnus
authors.initials: M
authors.lastname: Svartengren
authors.forename: Gunnar
authors.initials: G
authors.lastname: Engström
authors.forename: Martin
authors.initials: M
authors.lastname: Anderson
authors.forename: Jenny
authors.initials: J
authors.lastname: Hallberg
authors.forename: Goutham
authors.initials: G
authors.lastname: Edula
authors.forename: Maria Gerhardsson
authors.initials: MG
authors.lastname: de Verdier
authors.forename: Magnus
authors.initials: M
authors.lastname: Dahlbäck
authors.forename: Claes M
authors.initials: CM
authors.lastname: Lindberg
authors.forename: Kristina
authors.initials: K
authors.lastname: Forsman-Semb
authors.forename: Ulf
authors.initials: U
authors.lastname: Nihlén
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Fehniger
mesh_terms: D029481:Bronchitis, Chronic / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology / Q000235:genetics; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D018433:Twin Studies as Topic; D014427:Twins