Genetics of atopic diseases

Atopic (allergic) disorders develop out of a close interaction between genetic predisposition and environmental triggers. A unifying attribute underlying these disorders is atopy, defined as the predisposition of those affected to generate IgE antibodies to environmental antigens and to respond with immediate-type hypersensitivity reactions upon subsequent exposure. Atopy is a heritable trait, and recent studies have identified several genes that engender atopy by increasing either the production of or the responsiveness to IgE. Other genes that contribute to the development of allergic disorders include leukocyte histocompatibility alleles, which specify responsiveness to individual environmental antigens, and disease-related genes, which promote distinctive aspects of an allergic disorder, such as tissue localization. A model is presented whereby the evolution of specific allergic disorders is predicated on the confluence of predisposing genetic elements, coupled with exposure to environmental triggers.