Polymorphism of IgE gene in chronic urticaria

Our aim was to determine whether heterogeneity of the IgE (C epsilon) gene could be demonstrated in patients with chronic urticaria (CU). We performed Southern blots on DNA extracted from peripheral blood leucocytes of 20 patients with CU and 20 normal controls. Using a human C epsilon gene probe containing four exons of the constant segment of the IgE heavy chain, we showed the presence of a restriction fragment length polymorphism of the C epsilon gene segment in four of 20 patients with CU, but in none of 20 normal subjects. Family studies of two propositi revealed the presence of this C epsilon gene polymorphism in other family members. Our data show that a proportion of patients with CU have a polymorphism of the constant segment of the C epsilon gene. Further studies of this polymorphic gene fragment indicated that it was derived from duplication of the 3rd and 4th exons of functional C epsilon gene and was very likely to be located close to this gene. It raises the possibility that polymorphism of the functional C epsilon gene may affect expression of this gene. This could possibly lead to dysfunctional IgE-receptor interaction with consequent alteration in mediator release.