The role of interleukin-6 promoter polymorphism -174G/C in Saudi women with hypertensive disorders of pregnancy

OBJECTIVE: To study the relationship between -174 GC interleukin-6 single nucleotide polymorphism and hypertensive disorders of pregnancy (HDP) in Saudi women.

METHODS: In this case-control study, 109 HDP patients and 100 women with normal pregnancy as a control group were studied. The HDP study group constituted of 60 women with gestational hypertension (GH) and 49 women with preeclampsia (PE). All women were randomly selected from the antenatal clinic and the prenatal and postnatal wards at the Antenatal Clinic and the Obstetric Ward of King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia from April 2010 to December 2011. The -174 GC of IL-6 SNP was determined using real time polymerase chain reaction, allele discrimination technique.

RESULTS: Distribution of -174 GC of IL-6 genotype in HDP patients was GG (58.5%), GC (31.1%), and CC (10.4%), while in the control group was GG (67%), GC (30.9%), and CC (2.1%). The CC homozygosity was significantly associated with HDP (odds ratio [OR] = 5.76; 95% confidence interval [CI] 1.23-27.06, p=0.03). This association only manifested with GH (OR = 7.65; 95% CI = 1.54-38.03, p=0.01). However, no significant association was found with PE (OR = 3.48; 95% CI = 0.55-21.99, p=0.19).

CONCLUSION: The results indicate a positive association between -174 GC of IL-6 genotype and the risk of HDP. Genotypes CC and GC are associated with increased risk of GH but not with PE, suggesting that they are of differing genetic predisposition/pathophysiology.