Occurrence of +874T/A gene polymorphism of interferon-gamma in Iraqi atopic patients

Abstract

Traditionally, asthma, atopic dermatitis and allergic rhinitis, in addition to food allergy, categorized as atopic diseases, the term allergy refer to immediate hypersensitivity which used to describe the combined immediate and late phase reactions. This study aimed to determine serum total IgE level, eosinophil count, and serum level of IFN-γ, in relation to the age of atopic patients and genotyping of the IFN-γ gene at +874 T/A in relation to serum IFN-γ level. As well as comparing of IFN-γ concentrations of atopic patients according to genotypes in atopic patients and apparently healthy control. The studied groups were 25 apparently healthy controls and 75 atopic patients (25 asthma patients, 25 allergic rhinitis patients and 25 atopic dermatitis patients). The obtained results showed that, the prevalence of atopic diseases occurred in the age group between 21 and 40 (second group) are more than the age group less than 21 (first group) and the age group of more than 40, third group (p = .0001). Moreover, total IgE is significantly increased in the three atopic groups compare to control (P < .001) and IgE in all age groups is significantly high. The high eosinophil count was seen in patients of atopic subjects than in apparently healthy control (P < .01). Asthma and allergic rhinitis eosinophil count is significantly high in first and second groups but not in third age group and atopic dermatitis eosinophil count is low in atopic dermatitis in all age groups. Furthermore, significant decrease in serum IFN-γ levels was observed in asthmatic patients, slightly decrease in allergic rhinitis and slightly increase in dermatitis patients. TA genotype was higher frequency in control, allergic rhinitis and atopic dermatitis groups than AA and TT, in asthmatics, AA was higher than TA and TT. There was no deviation on Hardy-Weinberg equilibrium, non-significant difference between observed and expected genotypes. Also non-significant association was observed between genotypes in all studied groups according to odd ratio and fisher exact probability. This study concluded that the prevalence of atopic diseases occurred in the age group between 21 and 40 years more than the age group less than 21 years and the age group of more than 40 years. The age can affect some parameters of immune system in atopic patients namely IgE level, eosinophil count and IFN-γ. However, there is no relationship between +874 T/A IFN-γ genotypes and atopic diseases development risk in Iraqi atopic patients.