Abstract
Bronchial hyperresponsiveness is a fundamental characteristic of asthma thought to have a heritable component.
1
Longitudinal studies in children show that bronchial hyperresponsiveness precedes asthma and is a risk factor for the development of asthma.
2
,
3
Studies in both humans and animals have demonstrated a genetic predisposition to bronchial hyperresponsiveness,
2
–
10
such as greater concordance for this trait among monozygotic twins than among dizygotic twins.
9
,
10
Bronchial hyperresponsiveness to carbachol appears to be inherited as an autosomal dominant trait,
4
but the bimodal distribution of bronchial responsiveness to methacholine is not controlled by a single gene.
5
Although these studies confirm a strong . . .
