Exposure to gene-environment interactions before 1 year of age may favor the development of atopic dermatitis.

BACKGROUND: The aims of this study were to determine (1) the prevalence of atopic dermatitis (AD) in Seoul, Korea, and (2) the influence of environmental and genetic factors on disease risk. METHODS: A questionnaire survey was conducted in 5,036 primary school children and 4,607 middle school children in 2008. For each child, a modified version of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and a questionnaire assessing exposure to environmental variables were completed. RESULTS: In primary school children, the lifetime prevalence of itchy eczema was 24.3%, the 12-month prevalence of itchy flexural eczema was 18.0%, the lifetime prevalence of AD diagnosis was 31.3%, and the 12-month prevalence of AD treatment was 14.5%. In middle school children, the corresponding rates were 16.0, 10.8, 22.1, and 8.3%, respectively. These rates are significantly higher than those reported in similar studies conducted in 1995 and 2000. In both primary and middle school children, a parental history of allergic disease and a history of having moved into a newly built house before 1 year of age were independently associated with a risk for current AD. For current AD, the prevalence odds ratio was higher in the subgroup with both a genetic and a specific environmental risk factor than in the subgroup with no risk factor or subgroups with only one risk factor. CONCLUSIONS: The prevalence of AD in primary and middle school children in Seoul has increased. Its development may be influenced by gene-environment interactions, particularly before 1 year of age.ope