NCPA - National Center for Policy Analysis

Genetic Origin of Asthma

October 30, 2001

Genetic makeup appears to play a more important role than environmental factors such as cigarette smoke, pets or dust in the development of asthma in young children, report researchers.

Researchers interviewed the parents of more than 4,000 4-year-old identical and fraternal twins. Twins raised in the same home share a similar environment, but identical twins have all the same genes, too. In contrast, fraternal twins share as many genes as any other pair of siblings. Asthma rates were more similar among identical twins than non-identical twins, the researchers report in a recent issue of the Archives of Diseases in Childhood.

  • They calculated that genes account for 68 percent of asthma prevalence.
  • Exposure to similar allergens accounted for just 13 percent of asthma prevalence.
  • Genetic factors appear to be more important for girls than boys.

"Asthma is highly heritable, even in preschool children exposed to the same environmental allergens in the home," the researchers conclude.

The report adds to a growing body of research into the causes of asthma, a chronic respiratory disease that is more common today than in the past. While some studies have found the disorder is largely genetic, others have concluded that factors such as obesity and exposure to dust mites and cat dander play a more significant role.

It is also likely that asthma develops due to an interaction between hereditary and environmental factors, the study notes.

Source: G. Koeppen-Schomerus, J. Stevenson and R. Plomin, "Genes and environment in asthma: a study of 4 year old twins," Archives of Diseases in Childhood, November 2001; "Genes more important than environment for asthma," Reuters Health, October 22, 2001.


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