Objective: Interleukin-6 (IL-6) is a specific marker of early onset infections in the newborns. In recent years it has been suggested that in regulations of IL-6 activity could play a role the genetic polymorphism (-174G/C) in the promoter region of the gene coding for IL-6. The aim of our study was to analyse the frequency of -174G/C polymorphism of interleukin-6 gene as a genomic marker for individuals at an increased risk of early onset neonatal infection as result of intra-amniotic infection (IAI).
Material and method: A prospective study was conducted in 62 newborns treated in University Hospital tertiary neonatal intensive care unit. Intrauterine infection was diagnosed in 21 children and 41 neonates comprised control group. In the both groups we have analysed -174G/C polymorphism in the gene coding IL-6 using PCR/RFLP (polymerase chain reaction/restriction fragment length polymorphism) assays.
Results: We have observed the overrepresentation of homozygous genotypes -174C/C in the investigated group (9.5% vs. 7.3% in the controls). The frequency of heterozygous genotypes -174G/C was higher in investigated group 61.9% than in controls 56.1%. Homozygous wild type genotypes for -174G/G were detected in 28.6% and 36.6% in investigated group and controls, respectively. These proportions were consistent with the Hardy-Weinberg equilibrium. Analysing allelic frequency we have noticed overrepresentation of -174C alleles in the investigated group (40.5% vs. 35.4% in the controls, O.R. = 1.24, n.s.).
Conclusion: The presence of the C allele in the -174 position in the gene coding for IL-6 could play a role in the pathology of neonatal infection following IAI in the mother and probably is connected with decreased of immunological reaction.