Placental Genetic Variants in the Upstream Region of the FLT1 Gene in Preeclampsia

Soluble fms-like tyrosine kinase 1 (sFlt-1) is believed to be a prominent component in the pathogenesis of pre-eclampsia, although the precise etiology has remained elusive. In this study, the etiological role of FLT1 variant was further validated in pre-eclampsia by examining this association in a Japanese sample population.

The genotypes of three variants (rs4769613, rs12050029 and rs149427560) were examined in the upstream region of the FLT1 gene in placentas from preeclamptic (n=47) or normotensive control (n=49) pregnancy samples. Additionally, FLT1 mRNA levels in placenta were determined by qRT-PCR. ELISA was further used to detect circulating sFlt-1 levels in maternal sera. The intergroup comparisons were made using the Mann-Whitney U test or one way analysis of variance and P values of less than 0.05 were considered statistically significant.

First, the rs4769613 (C>T) and rs12050029 (G>A) genotypes were examined in placentas but no significant differences were found in the genotype or alleletype frequencies. Next, nearby short tandem repeat, rs149427560, was examined which manifested four size variants. In the genotypewise analysis, the frequency of the 474/476 heterozygote was significantly lower in pre-eclampsia (p<0.05). As expected, the FLT1 mRNA levels were significantly elevated in the pre-eclamptic placentas and sFlt-1 was higher in pre-eclamptic maternal sera. However, the genotype of these variants did not affect the FLT1 mRNA or serum sFlt-1 levels.

Our findings did not support the hypothesis that genetic variations around the FLT1 gene affect the subtle expression changes underlying the etiologic pathway of pre-eclampsia. The hypothesis deserves further investigation through a larger sample size.