Evidence for genetic associations between asthma, atopy, and bronchial hyperresponsiveness: A study of 8- to 18-yr-old twins

Abstract

We measured asthma in the last 12 mo, diagnosed by a respiratory physician at interview; atopy, defined by a positive skin prick test to any of eight common allergens; and bronchial hyperresponsiveness (BHR) to hypertonic saline, in 381 twin pairs aged 8 to 18 yr selected from the Australian Twin Registry - 183 monozygous (MZ) and 198 dizygous (DZ). The associations between twins, as measured by an odds ratio, were greater in MZ pairs compared with DZ pairs for asthma: 25.6 (95% confidence interval 11.3-57.8) versus 1.9 (1.0-3.5); atopy: 14.6 (7.1-30.1) versus 2.5 (1.4-4.5); and BHR: 14.1 (6.4-31.0) versus 4.2 (2.1-8.6) (all p < 0.002). The associations between each pair of traits within an ..