Polymorphisms in the tumor necrosis factor alpha and interleukin 1-beta promoters with possible gene regulatory functions increase the risk of preterm birth.

To investigate the relation between 19 selected single nucleotide polymorphisms in three cytokine genes, tumor necrosis factor alpha (TNFA), interleukin 1-beta (IL1B) and interleukin 6 (IL6) and preterm birth (<37 weeks' gestation).Case-control association study.A total of 117 singleton pregnant Danish Caucasian women, including 62 preterm birth cases and 55 controls (birth>or=37 weeks).Genotyping was performed using TaqMan probes and traditional sequencing. Descriptive statistics were carried out with Fisher's exact test and Wilcoxon rank-sum test. All genetic data were tested for Hardy-Weinberg equilibrium and analyzed using logistic regression, 2x2 proportions or chi(2). Haplotypes were estimated for each gene and permutation used for association testing.Women carrying the TNFA -857 C>T rare allele (T) and those homozygous for the IL1B -31 T>C and IL1B -511 C>T rare alleles (C and T) have an increased risk of preterm birth with OR 3.1 (95% CI: 1.0-10.3) and OR 6.4 (95% CI: 1.3-60.5), respectively. Two estimated TNFA haplotypes were associated with preterm birth with OR 3.1 (p=0.037) and OR 2.7 (p=0.045).Polymorphisms in the cytokine genes TNFA and IL1B may increase the risk of preterm birth, possibly by a dysregulation of the immune system in pregnancy.