Asthma: nature versus nurture
Clin Respir J (2012) 6:228-237
Environment accounts for around three-quarters of the variation in the severity of asthma symptoms, according to a study of 575 identical and non-identical twins, at least one of whom who suffered from the respiratory disease.
After adjusting for potential confounders (such as age, sex, current airway infection, smoking and body mass), genetic factors accounted for 24% of the difference in severity of asthma symptoms between the twins.
Environmental factors explained the remainder. Genetic factors also accounted for about 12% and 17% of the variation in the severity of wheezing and shortness of breath between the twins, but did not seem to significantly influence the likelihood of experiencing chest tightness or cough.
Symptom severity correlated weakly with asthma's pathophysiological changes, such as airway obstruction, responsiveness and inflammation.
The authors suggest that differences between the 'genetic architecture' that underlies symptom severity and that contributing to 'objectively measured asthma-related traits' might account for this weak correlation.
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