Considering that atopic diseases such as allergic rhinitis, atopic dermatitis, and allergic asthma have a differential prevalence among women and men, with prevalence differences depending on age (affecting young males more than females, higher in post pubertal females where the incidence of allergies increases to become superior or equivalent to that reported in post pubertal males), we can understand how IgE levels and sensibilization are influenced by the menstrual cycle, and, in particular, by sex hormones. This evidence concerns the gene IGHE and allergic disease.