[From atopic dermatitis to asthma]

Atopic dermatitis (AD) is the most common chronic skin disorder in infancy and childhood and is the main hallmark of atopic constitution. The disease is multifactorial, and although genetic predisposition is certainly a prerequisite, a number of environmental factors modulate the phenotypic expression of AD. The majority of affected children shows IgE sensitisation towards a large variety of foods and aeroallergens. Since at least 1600, it has been recognized that patients with AD have a high predisposition to develop asthma. Recent epidemiological studies show that AD is commonly seen in individuals from families with a history of asthma. In addition, in population where asthma is uncommon, AD is also uncommon. The sex distribution of AD and asthma is the same, with boys affected significantly more often by these two atopic diseases and in similar proportions. The ETAC project (Early Treatment of the Atopic Child) is a large multicenter, multi-national, double blind, placebo controlled, randomised trial. The main objective of the study is to stop the progression from AD to asthma in young children with AD using early therapeutic intervention with Cetirizine and the second objective is to investigate the main risk factors for the onset of asthma. The results of this study indicate that exposure to potent allergens such as cat or mite significantly increased the risk of sensitisation to these allergens. Prolonged breast feeding was associated with a lowest sensitisation rate to cow milk proteins and to egg. Therefore environmental factors seem to play a crucial role in IgE sensitisation in children with AD.