LONDON (Reuters Health) Oct 22 - Genetic factors have a greater influence than environmental factors on whether a child will develop asthma, according to a report published in the November issue of Archives of Disease in Childhood.
Dr. G. Koeppen-Schomerus, from King's College in London, and colleagues studied 4-year-old twins to determine the relative contribution of genetic and environmental factors to the development of childhood asthma. While asthma twin studies have been done before, none have focused on the development of asthma in preschool children.
The study group consisted of 1658 monozygotic twin pairs, 1651 dizygotic same-sex pairs, and 1601 dizygotic opposite-sex pairs. Asthma status was ascertained through parent postal questionnaire.
The overall prevalence of asthma was 18.4%. Genetic factors accounted for 68% of the prevalence, while shared and non-shared environmental factors accounted for only 13% and 19% of the prevalence, respectively, the researchers note.
"The present findings indicate that asthma is highly heritable, even in preschool children exposed to the same environmental allergens in the home," the authors say. The minor impact of shared environments is in agreement with study findings on older twins, they note.
No single gene is likely to determine asthma susceptibility, the researchers state. Genome screening studies have identified markers on most chromosomes that may contribute to asthma development. The researchers call for further studies to identify the genes responsible and to determine the non-shared environmental factors that play a role.
Arch Dis Child 2001;85:398-400. |
