Toll-like receptor 4 gene polymorphisms and preeclampsia: Lack of association in a Caucasian population

Abstract

Preeclampsia is a multifactorial disorder with genetic and environmental components. As Toll-like receptor 4 (TLR4) has an essential role in innate immune response, which is exaggeratedly activated in preeclampsia, our aim was to investigate whether two single nucleotide polymorphisms (SNPs) of the TLR4 gene - Asp299Gly (A896G) and Thr399lle (C1196T) - are associated with preeclampsia in a Caucasian population from Hungary. In a case- control study, we analyzed blood samples from 180 preeclamptic patients and 172 normotensive, healthy pregnant women with the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. The linkage disequilibrium (LD) profile of the TLR4 gene was investigated and tag SNPs were identified using data from the International HapMap Project. There were no significant differences in the genotype and allele frequencies of Asp299Gly and Thr399lle polymorphisms between the two study groups. Additionally, no significant difference was found in the distribution of the estimated haplotypes created by the two polymorphisms between the preeclamptic and the control group. Furthermore, no significant differences were detected in the genotype, allele and haplotype frequencies of Asp299Gly and Thr399lle TLR4 SNPs between patients with mild and severe preeclampsia, between patients with late and early onset of the disease, or between preeclamptic patients with and without fetal growth restriction. In conclusion, We did not find an association between TLR4 Asp299Gly and Thr399lle gene polymorphisms and preeclampsia. As the Thr399lle polymorphism is a highly informative tag SNP of the TLR4 gene, our results suggest that variations in this genomic region are not associated with preeclampsia. Nevertheless, further studies are required with determination of fetal TLR4 genotypes to explore the role of TLR4 gene polymorphisms in the risk of preeclampsia, especially in ethnically different populations.