Gene-environment interaction in allergic disease: More questions, more answers?

Abstract

Allergic disease results from the interplay between individual genetic susceptibility and environmental exposures. 1 The genetic contribution to allergic disease has been estimated from twin studies to be generally greater than 50%, with heritability estimates ranging from 36% to 79%. 2 The environmental contribution to allergic disease is evidenced by the increase in the prevalence of allergy in the past decades. This increase is the result of changes in the environment. Interestingly, children raised on farms appear to have been protected against this increase in prevalence compared with children not raised on farms. Protective lifestyle factors on the farm include exposure to livestock, the consumption of unpasteurized farm milk, and increased endotoxin levels in the farm environment. 3 The