Background: Genetic and environmental factors are known to play a role in the development
of atopic diseases, such as asthma, eczema, and rhinitis. However, the atopy gene (or
genes) has yet to be defined. Studies of familial asthma have identified several regions that
may contain genes predisposing to atopy, but the data for candidate regions do not show
agreement, which may be due to heterogeneity, ascertainment bias, or stochastic factors.
Factors such as an early age of onset, a positive family history, and a clearly defined …