Analysis of an interleukin-6 gene promoter polymorphism in women with endometriosis by pyrosequencing

J Soc Gynecol Investig. 2003 Jan;10(1):32-6.


Interleukin (IL)-6 has been implicated in the etiology of endometriosis. A single nucleotide polymorphism (SNP) at position -174 in the IL-6 gene promoter appears to influence IL-6 transcription rates in vitro and basal IL-6 levels in vivo. We determined the genotype and the allele frequencies of the -174 IL-6 promoter polymorphism and the corresponding IL-6 serum levels in women with endometriosis. The pyrosequencing technique was used to assess the IL-6 genotypes in 94 women with histologically confirmed endometriosis (study group). A series of 70 healthy women without history of uterine disease served as clinical controls (control group).Allele frequencies for the G allele among women with and without endometriosis were 59.6% and 55.0%, respectively (P =.430; odds ratio [OR] 0.83, 95% confidence interval [CI] 0.53, 1.29). Homozygotes for the protective allele C were present in 17.0% of women with endometriosis and in 18.6% of controls were homozygous for the protective allele C (P =.797; OR 0.90, 95% CI 0.40, 2.02). When patients with various disease manifestations were compared, we found an association between the -174 G allele and chocolate cysts (P =.037). Serum levels of IL-6 were significantly higher in women with endometriosis than in controls (P <.001), with highest levels in women with chocolate cysts. There was no association between serum IL-6 levels and IL-6 genotype. The IL-6 promoter polymorphism -174 G/C does not contribute significantly to overall disease susceptibility but does predispose the carrier to distinct endometriosis with chocolate cysts. A genetically determined high IL-6 response might play a pathogenic role in this disease condition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Endometriosis / genetics*
  • Female
  • Gene Frequency
  • Genetic Predisposition to Disease
  • Genotype
  • Humans
  • Infertility, Female / genetics
  • Interleukin-6* / blood
  • Interleukin-6* / genetics*
  • Ovarian Cysts / genetics
  • Polymerase Chain Reaction
  • Polymorphism, Genetic*
  • Promoter Regions, Genetic / genetics*


  • Interleukin-6