Interferon gamma gene polymorphism as a biochemical marker in Egyptian atopic patients.

OBJECTIVES The aim of this study was to clarify the role of interferon (IFN) gamma in the diagnosis and follow-up of atopic patients. We genotyped the IFN-gamma polymorphism at position +874 to examine the relationship between serum levels of IFN-gamma and disease severity and the role of IFN-gamma as a biochemical and immunologic marker. METHODS The study population comprised 75 patients suffering from atopic asthma, atopic dermatitis, and allergic rhinitis (25 each), and 25 control participants. Total immunoglobulin (Ig) E and serum IFN-gamma were measured by enzyme-linked immunosorbent assay, the IFN-gamma polymorphism at position +874 was determined by amplification refractory mutation system-polymerase chain reaction, and eosinophil counts were recorded. RESULTS There was a significant association between genotype and the frequency of the A allele of the +874T/A polymorphism in atopic patients when compared with controls (P < .001). In all 3 groups, there was a significant increase in total IgE levels and eosinophil counts, and a decrease in serum IFN-gamma levels towards the presence of homozygous AA compared with homozygous TT. CONCLUSIONS The IFN-gamma gene polymorphism at position +874 contributes to susceptibility to atopic diseases by decreasing the amount of IFN-gamma. Identification of variants of IFN-gamma gene signalling and its role in the development of atopic diseases provides a focus for the development of novel diagnostic and therapeutic strategies for these diseases.