Objective: Recent studies suggest that preterm delivery might be conditioned genetically. The main aim of this study was to examine the relationship between spontaneous preterm delivery (PTD) and the carriage of polymorphic genes that code the following cytokines: interleukin-1beta [IL1beta (+3953C>T)], interleukin-6 promoter [IL6 (-174G>C)], tumour necrosis factor-alpha promoter [TNFalpha (-308G>A)] and interleukin-1 receptor antagonist (IL1RN) in the population of Polish women.
Methods: A case-control study. 125 Caucasian women were examined, among them 62 cases and 63 controls. Case subjects were defined as those who had a delivery at less than 366 weeks of gestation due to either preterm premature rupture of membranes or preterm labour while control subjects gave birth at term. Detailed demographic, medical and obstetric data based on structured questionnaire and medical record were collected. Maternal venous blood samples were collected after the delivery and analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFPL) techniques for the presence of each of the allelic variants. Logistic regression model was used to compute odds ratio and its 95% confidence intervals.
Results: Women that carried IL1RN*2 were found to be at an increased risk of preterm delivery OR = 2.75 (95% CI: 1.02-4.13). No correlation between IL-1beta, IL-6 and TNF-alpha gene polymorphisms and the risk of PTD was found. Coincidence of IL1RN polymorphism (genotype IL1RN*1/ IL1RN*2, IL1RN*1/ IL1RN*3, IL1RN*2/ IL1RN*3) with IL-6 promoter polymorphism (genotype GG, GC) multiplied the risk of preterm delivery OR = 3.02 (95% CI: 1.00-8.91).
Conclusions: Maternal carriage of the IL1RN*2 allele appears to be associated with an elevated risk of preterm delivery in the population of Polish women. Coincidence of IL1RN*2 with at least one copy of IL-6 allele G might increase the risk of preterm delivery even further.