Specific IgE - one gene fits all?

Specific immunoglobulin E (IgE) production is increased in allergic disease s. Research into the main factors of IgE responsiveness are complicated by different steps in the antibody production from somatic recombination to is otype switching and more general amplification loops. We have therefore sta rted a positional cloning approach to identify relevant genes. Ninety-seven families, each with two children with asthma, were examined. Of these, 415 persons were analysed for 13 specific IgE against major allergens and geno typed for 351 microsatellite markers distributed in equal distances over th e genome. Of the initial set of allergens, four major groups were identifie d where the most frequent allergen was analysed consecutively: birch for th e tree group, mixed grass for grass pollen, Dermatophagoides pteronyssinus for dust mites and cat for the pet group. Parental sensitization with the s ame allergen seemed to be a weak risk factor for the children. Also several environmental exposure variables showed only moderate effects on the preva lence of IgE antibodies in children. A quantitative linkage analysis of the specific IgE values gave evidence for one or two linked regions but was di fferent for each allergen. From this initial observation it is likely that the factors for genetic upregulation of IgE responsiveness cannot be descri bed by the action of a single major gene. Genes seem to be more likely to i nfluence general IgE responsiveness at the amplification level rather than at the level of differentiation into fine specificity of antibodies.