Introduction EGEA (Epidemiological study on the genetics and environmental aspects of asthma, bronchial hyperresponsiveness and atopy), a case control and family study including 2048 individuals, was initiated to look for environmental and genetic risk factors for asthma. A synthesis of the results obtained since 2002 on the phenotypes and environmental aspects of asthma severity and allergy are presented in this article.

Methods/Results The results support the hypothesis that hormonal factors play a role in asthma severity and in various allergic markers of asthma. A greater body mass index was related to a more severe form of asthma in women with early menarche. Associations were found between markers of allergy (eosinophils, IgE and atopy) and hormone-dependent events in women (premenstrual asthma, menopause and oral contraceptive use) have been found. In asthmatics, exposure to agents known to be associated with occupational asthma, active and passive smoking were associated with an increased clinical asthma severity score. The study underlines the protective role of a rural environment and exposure to pets in early life on allergy markers in adulthood, supporting the hygiene hypothesis.

Conclusions New hypotheses will be tested in the near future during the second stage of this survey.