Preeclampsia is a heritable pregnancy disorder that presents new onset hypertension and proteinuria. We have previously reported genetic linkage to preeclampsia on chromosomes 2q, 5q and 13q in an Australian/New Zealand (Aust/NZ) familial cohort. This current study centered on identifying ]the susceptibility gene(s) at the 5q locus. We firstly prioritized candidate genes using a bioinformatic tool designed for this purpose. We then selected a panel of known SNPs within 10 prioritized genes and genotyped them in an extended set of the Aust/NZ families and in a very large, independent Norwegian case/control cohort (1,139 cases, 2,269 controls). In the Aust/NZ cohort we identified evidence of a genetic association for the endoplasmic reticulum aminopeptidase 1 (ERAP1) gene (rs3734016; p uncorr =0.009) and for the endoplasmic reticulum aminopeptidase 2 (ERAP2) gene (rs2549782; p uncorr =0.004). In the Norwegian cohort we identified evidence of a genetic association for ERAP1 (rs34750; p uncorr =0.011) and for ERAP2 (rs17408150; p uncorr =0.009). The ERAP2 SNPs in both cohorts remained statistically significant (rs2549782; p corr =0.018; rs17408150; p corr =0.039) after corrections at an experiment-wide level. The ERAP1 and ERAP2 genes encode enzymes that are reported to play a role in blood pressure regulation and essential hypertension in addition to innate immune and inflammatory responses. Perturbations within vascular, immunological and inflammatory pathways constitute important physiological mechanisms in preeclampsia pathogenesis. We herein report a novel preeclampsia risk locus, ERAP2, in a region of known genetic linkage to this pregnancy specific disorder.

This study ascertains high PPV of pre-eclampsia in the MBRN using broader traditional criteria, although the PPV decreases through assessment using restricted modern criteria. This illustrates how inclusion of direct measurements may improve registration of complex disorders defined by changing diagnostic criteria.

Elucidating the genetic architecture of preeclampsia is a major goal in obstetric medicine. We have performed a genome-wide association study (GWAS) for preeclampsia in unrelated Australian individuals of Caucasian ancestry using the Illumina OmniExpress-12 BeadChip to successfully genotype 648,175 SNPs in 538 preeclampsia cases and 540 normal pregnancy controls. Two SNP associations (rs7579169, p = 3.58×10 −7 , OR = 1.57; rs12711941, p = 4.26×10 −7 , OR = 1.56) satisfied our genome-wide significance threshold (modified Bonferroni p<5.11×10 −7 ). These SNPs reside in an intergenic region less than 15 kb downstream from the 3′ terminus of the Inhibin, beta B ( INHBB ) gene on 2q14.2. They are in linkage disequilibrium (LD) with each other (r 2 = 0.92), but not (r 2 <0.80) with any other genotyped SNP ±250 kb. DNA re-sequencing in and around the INHBB structural gene identified an additional 25 variants. Of the 21 variants that we successfully genotyped back in the case-control cohort the most significant association observed was for a third intergenic SNP (rs7576192, p = 1.48×10 −7 , OR = 1.59) in strong LD with the two significant GWAS SNPs (r 2 >0.92). We attempted to provide evidence of a putative regulatory role for these SNPs using bioinformatic analyses and found that they all reside within regions of low sequence conservation and/or low complexity, suggesting functional importance is low. We also explored the mRNA expression in decidua of genes ±500 kb of INHBB and found a nominally significant correlation between a transcript encoded by the EPB41L5 gene, ∼250 kb centromeric to INHBB , and preeclampsia (p = 0.03). We were unable to replicate the associations shown by the significant GWAS SNPs in case-control cohorts from Norway and Finland, leading us to conclude that it is more likely that these SNPs are in LD with as yet unidentified causal variant(s).

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Pre-eclampsia is an idiopathic pregnancy disorder promoting morbidity and mortality to both mother and child. Delivery of the fetus is the only means to resolve severe symptoms. Women with pre-eclamptic pregnancies demonstrate increased risk for later life cardiovascular disease (CVD) and good evidence suggests these two syndromes share several risk factors and pathophysiological mechanisms. To elucidate the genetic architecture of pre-eclampsia we have dissected our chromosome 2q22 susceptibility locus in an extended Australian and New Zealand familial cohort. Positional candidate genes were prioritized for exon-centric sequencing using bioinformatics, SNPing, transcriptional profiling and QTL-walking. In total, we interrogated 1598 variants from 52 genes. Four independent SNP associations satisfied our gene-centric multiple testing correction criteria: a missense LCT SNP (rs2322659, P = 0.0027), a synonymous LRP1B SNP (rs35821928, P = 0.0001), an UTR-3 RND3 SNP (rs115015150, P = 0.0024) and a missense GCA SNP (rs17783344, P = 0.0020). We replicated the LCT SNP association (P = 0.02) and observed a borderline association for the GCA SNP (P = 0.07) in an independent Australian case-control population. The LRP1B and RND3 SNP associations were not replicated in this same Australian singleton cohort. Moreover, these four SNP associations could not be replicated in two additional case-control populations from Norway and Finland. These four SNPs, however, exhibit pleiotropic effects with several quantitative CVD-related traits. Our results underscore the genetic complexity of pre-eclampsia and present novel empirical evidence of possible shared genetic mechanisms underlying both pre-eclampsia and other CVD-related risk factors.

The etiology of preeclampsia is complex, with susceptibility being attributable to multiple environmental factors and a large genetic component. Although many candidate genes for preeclampsia have been suggested and studied, the specific causative genes still remain to be identified. Catechol-O-methyltransferase (COMT) is an enzyme involved in catecholamine and estrogen degradation and has recently been ascribed a role in development of preeclampsia. In the present study, we have examined the COMT gene by genotyping the functional Val108/158Met polymorphism (rs4680) and an additional single-nucleotide polymorphism, rs6269, predicting COMT activity haplotypes in a large Norwegian case/control cohort (ncases= 1135, ncontrols= 2262). A low COMT activity haplotype is associated with recurrent preeclampsia in our cohort. This may support the role of redox-regulated signaling and oxidative stress in preeclampsia pathogenesis as suggested by recent studies in a genetic mouse model. The COMT gene might be a genetic risk factor shared between preeclampsia and cardiovascular diseases.

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Variation in the Storkhead box-1 (STOX1) gene has previously been associated with pre-eclampsia. In this study, we assess candidate single nucleotide polymorphisms (SNPs) in STOX1 in an independent population cohort of pre-eclamptic (n = 1.139) and non-pre-eclamptic (n = 2.269) women (the HUNT2 study). We also compare gene expression levels of STOX1 and its paralogue, Storkhead box-2 (STOX2) in decidual tissue from pregnancies complicated by pre-eclampsia and/or fetal growth restriction (FGR) (n = 40) to expression levels in decidual tissue from uncomplicated pregnancies (n = 59). We cannot confirm association of the candidate SNPs to pre-eclampsia (P > 0.05). For STOX1, no differential gene expression was observed in any of the case groups, whereas STOX2 showed significantly lower expression in deciduas from pregnancies complicated by both pre-eclampsia and FGR as compared with controls (P = 0.01). We further report a strong correlation between transcriptional alterations reported previously in choriocarcinoma cells over expressing STOX1A and alterations observed in decidual tissue of pre-eclamptic women with FGR.