Genetic association of interleukin 18 (-607C/A, rs1946518) single nucleotide polymorphism with asthmatic children, disease severity and total IgE serum level

Introduction
Bronchial asthma is a chronic inflammatory disease. Interleukin 18 (IL-18) single nucleotide polymorphisms (SNPs) can influence IL-18 production and activity. IL-18-607C/A and -137 C/G are two of the commonly studied SNPs of IL-18 due to their role in the etiopathogenesis of allergic diseases.

Aim of the study
The case control study was conducted to investigate the genetic association between IL-18-607C/A polymorphism and pediatric asthma. Also attempts were made to evaluate the prognostic effect of -607C/A SNP with disease severity and total serum IgE.

Material and methods
The case control study was conducted on 60 asthmatic children and 40 healthy subjects; aged 2 to 12 years. PCR-RFLP was used to detect IL-18-607C/A SNP and total serum IgE level was detected using ELISA technique.

Results
Regarding IL-18-607C/A SNP, the frequency of the A allele and CA genotype was significantly higher in asthmatic children compared to healthy control subjects (p < 0.001). Further on, asthmatic children carrying the AA/AC genotype of -607C/A SNP were associated with an increased risk of occurrence of asthma (OR = 6.417; CI = 2.432-17.289). IgE was higher in asthmatic patients carrying the heterozygous CA genotype compared to patients carrying the AA and CC genotypes (p = 0.054).

Conclusion
The frequency of the heterozygous CA genotype and A allele in IL-18-607C/A SNP was higher in asthmatic children. There is no association between the severity of asthma and -607C/A SNP. Total IgE was higher in patients carrying the CA genotypes compared to patients carrying the AA and CC genotypes, respectively.