IL-6 gene promoter polymorphisms: genetic susceptibility to recurrent pregnancy loss.

Recurrent pregnancy loss (RPL) is defined as three or more pregnancy losses before 20 weeks. RPL is a multifactorial condition with several etiologic factors including genetic abnormalities of the parents, anatomical, endocrinological, hematologic and immunologic abnormalities, infections, nutritional and environmental factors. The causes of pregnancy loss in about half of the women with RPL even after extensive investigations remain unknown. We analyzed IL-6 -174 G/C, -572 G/C, -597 G/A, -1363 G/T, -2954 G/C promoter region polymorphisms in 113 RPL patients and 113 healthy subjects by using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) assay. The -174G/C genotypic and -174C allelic frequency and the -2954G/C genotypic and -2954C allelic frequency of IL-6 was higher in RPL patients than healthy controls and a significant association was found between RPL and -174G/C, -2954G/C polymorphisms (p < 0.0001, OR: 0.28, 95% CI: 0.15-0.51, p < 0.034, OR: 0.16, 95% CI: 0.01-1.12 respectively). We found remarkably similar frequencies in RPL patients compared to controls for IL-6 -572G/C,-597G/A and -1363G/T genotypes/alleles and no association was observed between RPL and these polymorphisms. Our study supported that IL-6 -174G/C and -2954G/C polymorphisms were associated with an increased risk of RPL in Turkish patients (Tab. 3, Ref. 24).