Asthma Linked More to Genes than Environment

The study was published in the Archives of Disease in Childhood (2001;85:398-400), a specialty journal of the British Medical Journal.

Researchers conducted a survey of the parents of 4,910 four-year-old twins. All were born in the UK between 1994 and 1995. Parents were asked whether their twins were identical or nonidentical and what treatment their children had been given for asthma. Identical twins share all their genetic makeup but nonidentical twins share only half. Thus, finding similar rates of asthma in identical twins would suggest that genetic factors are more responsible.

The results of the survey showed that identical twins had more similar rates than nonidentical twins. Using statistical techniques to estimate heritability, the researchers found that genes by far accounted for the largest share of asthma prevalence at 68%.
In contrast, being exposed to environmental allergens accounted for only 13% and different environmental exposure accounted for 19%. The researchers concluded that enivornmental factors such as family diet and air pollution are likely to be much less important than genetic makeup. However, they stress that many genes are probably involved in the development of asthma.




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