title: Genetic and environmental risk factors for asthma: a cotwin-control study.
abstract: In complex diseases of genetic etiology such as asthma and atopy, it is difficult to differentiate causes of disease from consequences, and quantitate the importance of such causative factors. We examined possible risk factors for the development of wheezing and bronchial hyperresponsiveness in a cotwin-control study nested within a larger community-based twin-family study. In 62 monozygotic (MZ) twin pairs discordant for a history of wheezing, skin prick test to house dust extract was the most important discriminator, followed by sensitization to cat and cockroach allergens. In contrast, 62 dizygotic (DZ) discordant twin pairs differed additionally in sensitization to grass pollens and fungi. Markers such as serum haptoglobin, serum magnesium, and alpha-1-antitrypsin levels did not differ significantly between discordant twins. This MZ/DZ difference suggests that pollen allergy in asthmatics is more an epiphenomenon due to a genetic correlation between asthma and the allergic diathesis, whereas indoor allergens are likely to be direct environmental causes of asthma.
authors.affiliation: Epidemiology Unit, Queensland Institute of Medical Research, Brisbane, Australia.
authors.forename: D L
authors.initials: DL
authors.lastname: Duffy
authors.forename: C A
authors.initials: CA
authors.lastname: Mitchell
authors.forename: N G
authors.initials: NG
authors.lastname: Martin
mesh_terms: D000328:Adult; D000368:Aged; D016902:Air Pollution, Indoor / Q000009:adverse effects; D000485:Allergens / Q000009:adverse effects; D000818:Animals; D001249:Asthma / Q000209:etiology / Q000235:genetics*; D015415:Biomarkers / Q000097:blood; D016535:Bronchial Hyperreactivity / Q000235:genetics / Q000503:physiopathology; D016022:Case-Control Studies; D002415:Cats; D015984:Causality; D003058:Cockroaches / Q000276:immunology; D004200:Diseases in Twins; D004391:Dust / Q000009:adverse effects; D004777:Environment; D005260:Female; D005658:Fungi / Q000276:immunology; D006197:Hair / Q000276:immunology; D006242:Haptoglobins / Q000032:analysis / Q000235:genetics; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology / Q000235:genetics; D008274:Magnesium / Q000097:blood; D008297:Male; D008875:Middle Aged; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000009:adverse effects; D012135:Respiratory Sounds / Q000209:etiology / Q000235:genetics; D012307:Risk Factors; D012882:Skin Tests; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics; D000515:alpha 1-Antitrypsin / Q000032:analysis / Q000235:genetics
chemical_list: D000485:Allergens; D015415:Biomarkers; D004391:Dust; D006242:Haptoglobins; D000515:alpha 1-Antitrypsin; D008274:Magnesium