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Original Article
 

Polymorphisms in IL4 and IL4RA Confer Susceptibility to Asthma
 

AA Amirzargar,1,2 M Movahedi,3 N Rezaei,4,5 B Moradi,1 S Dorkhosh,1 M Mahloji,3 SA Mahdaviani3

1 Immunogenetic Laboratory, Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
2 Molecular Immunology Research Center, Tehran University of Medical Sciences, Tehran, Iran
3 Department of Allergy and Clinical Immunology, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
4 Pediatrics Center of Excellence, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran
5 Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran

J Investig Allergol Clin Immunol 2009; Vol. 19(6): 433-438
 

 Abstract


Background: Asthma is a complex disease that is caused by genetic and environmental factors. The production of interleukin (IL)-4, which can influence mast cell responsiveness to immunoglobulin (Ig) E–mediated signaling, could be modified by genetic variants in the IL-4 promoter.

Objective: To investigate the association between the IL-4 and IL-4RA promoter polymorphisms and asthma in a sample of Iranian patients.

Methods: We used polymerase chain reaction with sequence-specific primers to investigate the allele and genotype frequencies of 2 polymorphic genes coding for IL-4 and IL-4RA in 59 Iranian patients with asthma and 139 healthy controls.

Results: The most frequent genotypes in the patient group were IL-4 TC (–590), IL-4 TC (–33), IL-4 GT (–1098), and IL-4RA GA (+1902). In contrast, the frequencies of IL-4 CC (–590), IL-4 CC (–33), IL-4 TT (–1098), and IL-4RA AA (+1902) were significantly lower in the patient group than in the control group. The most frequent haplotypes in our patients were IL-4 TCT and GTC at positions –1098, –590, –33. The mean total serum IgE level
in patients with the TTT/GCC genotype was 258.8 IU/mL, which was significantly higher than the 95.4 IU/mL observed for other genotypes.

Conclusion: We showed a strong association between the polymorphisms of the IL-4 gene promoter at positions –590, –33 and –1098 and bronchial asthma. We also demonstrated an association between their haplotypes and serum total IgE.

Key words: Asthma. Genetic polymorphism. IL-4. IgE.