Editor—Atopy, a familial clinical syndrome of asthma, rhinitis, and eczema, is characterised by IgE mediated allergy, which results from genetic and environmental events. The disease is immunologically defined by the presence of specific IgE antibodies to common allergens and raised total serum IgE concentrations. Also, because of its high prevalence, age dependent penetrance, and assumed heterogeneity, the mode of inheritance is unknown.1 Several genes which affect IgE responsiveness have been reported.2 Among the genes that have been reported to affect the atopic phenotype, that for IL4 regulates the production of IgE.3 4 Through its receptor (IL4-R), IL4 signals target cells and tissues to mount a response. The IL4-R α chain binds IL4 and mediates its effect through kinases attached to the intracellular domain.5 TheIL4-Rα coding gene has been localised to the short arm of chromosome 16 (16p12.1).6 Sharing of maternal markers flanking the IL4-Rα gene was recently found in atopy.7 A gain of function mutation in the IL4-Rα gene was recently described, and it was reported to be associated with higher levels of expression of CD23 by IL-4, severe atopic dermatitis, raised serum IgE level, or a specific response to a common allergen in a case-control study with 20 affected and 30 unaffected adults in …