Pre-eclampsia is a common and complex pregnancy disorder that often involves impaired placental development. In order to identify altered gene expression in pre-eclamptic placenta, we sequenced ...placental transcriptomes of nine pre-eclamptic and nine healthy pregnant women in pools of three. The differential gene expression was tested both by including all the pools in the analysis and by excluding some of the pools based on phenotypic characteristics. From these analyses, we identified altogether 53 differently expressed genes, a subset of which was validated by qPCR in 20 cases and 19 controls. Furthermore, we conducted pathway and functional analyses which revealed disturbed vascular function and immunological balance in pre-eclamptic placenta. Some of the genes identified in our study have been reported by numerous microarray studies (BHLHE40, FSTL3, HK2, HTRA4, LEP, PVRL4, SASH1, SIGLEC6), but many have been implicated in only few studies or have not previously been linked to pre-eclampsia (ARMS2, BTNL9, CCSAP, DIO2, FER1L4, HPSE, LOC100129345, LYN, MYO7B, NCMAP, NDRG1, NRIP1, PLIN2, SBSPON, SERPINB9, SH3BP5, TET3, TPBG, ZNF175). Several of the molecules produced by these genes may have a role in the pathogenesis of pre-eclampsia, and some could qualify as biomarkers for prediction or detection of this pregnancy complication.
Preeclampsia (PE) is a common vascular disease of pregnancy with genetic predisposition. Dysregulation of the complement system has been implicated, but molecular mechanisms are incompletely ...understood. In this study, we determined the potential linkage of severe PE to the most central complement gene,
. Three cohorts of Finnish patients and controls were recruited for a genetic case-control study. Participants were genotyped using Sequenom genotyping and Sanger sequencing. Initially, we studied 259 Finnish patients with severe PE and 426 controls from the Southern Finland PE and the Finnish population-based PE cohorts. We used a custom-made single nucleotide polymorphism (SNP) genotyping assay consisting of 98 SNPs in 18 genes that encode components of the complement system. Following the primary screening,
was selected as the candidate gene and consequently Sanger sequenced. Fourteen SNPs from
were also genotyped by a Sequenom panel in 960 patients with severe PE and 705 controls, including already sequenced individuals. Three of the 43 SNPs observed within
were associated with severe PE: rs2287845 (
= 0.038, OR = 1.158), rs366510 (
= 0.039, OR = 1.158), and rs2287848 (
= 0.041, OR = 1.155). We also discovered 16 SNP haplotypes with extreme linkage disequilibrium in the middle of the gene with a protective (
= 0.044, OR = 0.628) or a predisposing (
= 0.011, OR = 2.110) effect to severe PE depending on the allele combination. Genetic variants associated with PE are located in key domains of C3 and could thereby influence the function of C3. This is, as far as we are aware, the first candidate gene in the complement system with an association to a clinically relevant PE subphenotype, severe PE. The result highlights a potential role for the complement system in the pathogenesis of PE and may help in defining prognostic and therapeutic subgroups of preeclamptic women.
Preeclampsia is a multisystem disorder of pregnancy, originating in the placenta. Cytochrome P450 (CYP)-dependent eicosanoids regulate vascular function, inflammation, and angiogenesis, which are ...mechanistically important in preeclampsia.
We performed microarray screening of placenta and decidua (maternal placenta) from 25 preeclamptic women and 23 control subjects. The CYP subfamily 2J polypeptide 2 (CYP2J2) was upregulated in preeclamptic placenta and decidua. Reverse-transcription polymerase chain reaction confirmed the upregulation, and immunohistochemistry localized CYP2J2 in trophoblastic villi and deciduas at 12 weeks and term. The CYP2J2 metabolites, 5,6-epoxyeicosatrienoic acid (EET), 14,15-EET, and the corresponding dihydroxyeicosatrienoic acids, were elevated in preeclamptic women compared with controls in the latter two thirds of pregnancy and after delivery. Stimulating a trophoblast-derived cell line with the preeclampsia-associated cytokine tumor necrosis factor-α enhanced CYP2J2 gene and protein expression. In 2 independent rat models of preeclampsia, reduced uterine-perfusion rat and the transgenic angiotensin II rat, we observed elevated EET, dihydroxyeicosatrienoic acid, and preeclamptic features that were ameliorated by the CYP epoxygenase inhibitor N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide (MsPPOH). Uterine arterial rings of these rats also dilated in response to MsPPOH. Furthermore, 5,6-EET could be metabolized to a thromboxane analog. In a bioassay, 5,6-EET increased the beating rate of neonatal cardiomyocytes. Blocking thromboxane synthesis reversed that finding and also normalized large-conductance calcium-activated potassium channel activity.
Our data implicate CYP2J2 in the pathogenesis of preeclampsia and as a potential candidate for the disturbed uteroplacental remodeling, leading to hypertension and endothelial dysfunction.
Preeclampsia is a vascular pregnancy disorder that often involves impaired placental development. HO-1 (heme oxygenase 1, encoded by HMOX1) is a stress response enzyme crucial for endothelial and ...placental function. Long version of the guanine–thymine (GTn) microsatellite in the HMOX1 promoter decreases HO-1 expression, and the long maternal repeat is associated with late-onset preeclampsia. Our aim was to study whether the length of fetal repeat is associated with mother’s preeclampsia, whether the length of fetal and maternal repeats affect HO-1 levels in placenta and maternal serum, and whether HO-1 levels are altered in preeclampsia. We genotyped the repeat in the cord blood of 609 preeclamptic and 745 nonpreeclamptic neonates. HO-1 levels were measured in 36 placental samples, and in the first (222 cases/243 controls) and third (176 cases/53 controls) pregnancy trimester serum samples using enzyme-linked immunosorbent assay. The long fetal GTn repeat was associated with preeclampsia and its severe and early-onset subtypes. Interaction analysis suggested the maternal and fetal effects to be independent. Placental or serum HO-1 levels were not altered in preeclamptics, possibly reflecting heterogeneity of preeclampsia. Carriers of the long fetal and maternal repeats had lower placental and serum HO-1 levels, respectively, providing functional evidence for the association. We conclude that the long fetal GTn repeat may increase mother’s risk for especially severe and early-onset preeclampsia. The fetal and maternal risk alleles likely predispose to different disease subtypes.
Preeclampsia is a serious and phenotypically heterogeneous vascular pregnancy disorder. Heme oxygenase-1 (HO-1) is a stress response enzyme that may protect the maternal endothelium and facilitate ...adequate metabolic adaptation to pregnancy by its antioxidant and anti-inflammatory functions. HO-1 stress response is modulated by HO-1 gene (HMOX1) polymorphisms. Individuals with the long allele of a guanine-thymine (GTn) microsatellite repeat located in the promoter region of HMOX1 have a higher risk of cardiometabolic diseases compared with those with the short allele. We investigated whether the long GTn allele of HMOX1 is associated with subtypes of preeclampsia. The GTn repeat was genotyped in 759 patients and in 779 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort using DNA fragment analysis. In subtype analyses, the long-long (LL) genotype was associated with nonsevere (additive modelodds ratio OR, 1.94; 95% confidence interval CI, 1.13–3.31; recessive modelOR, 1.39; 95% CI, 1.02–1.89) and late-onset (additive modelOR, 1.44; 95% CI, 1.02–2.05; recessive modelOR, 1.28; 95% CI, 1.02–1.59) preeclampsia and with preeclampsia without a small-for-gestational-age infant (recessive modelOR, 1.27; 95% CI, 1.02–1.58). The long allele was associated with nonsevere (OR, 1.35; 95% CI, 1.07–1.70) and late-onset (OR, 1.21; 95% CI, 1.03–1.42) preeclampsia and with preeclampsia without a small-for-gestational-age infant (OR, 1.19; 95% CI, 1.02–1.40). Moreover, both the LL genotype and the long allele were associated with preeclampsia in women who had smoked during pregnancy. In conclusion, the GTn long allele seems to predispose to late-onset, less severe form of preeclampsia. This finding supports the role of HO-1 in the pathogenesis of preeclampsia and suggests that the HO-1 pathway may provide a potential target for the treatment of preeclampsia.
Pre-eclampsia is a common pregnancy disorder that is a major cause for maternal and perinatal mortality and morbidity. Variants predisposing to pre-eclampsia might be under negative evolutionary ...selection that is likely to keep their population frequencies low. We exome sequenced samples from a hundred Finnish pre-eclamptic women in pools of ten to screen for low-frequency, large-effect risk variants for pre-eclampsia. After filtering and additional genotyping steps, we selected 28 low-frequency missense, nonsense and splice site variants that were enriched in the pre-eclampsia pools compared to reference data, and genotyped the variants in 1353 pre-eclamptic and 699 non-pre-eclamptic women to test the association of them with pre-eclampsia and quantitative traits relevant for the disease. Genotypes from the SISu project (n = 6118 exome sequenced Finnish samples) were included in the binary trait association analysis as a population reference to increase statistical power. In these analyses, none of the variants tested reached genome-wide significance. In conclusion, the genetic risk for pre-eclampsia is likely complex even in a population isolate like Finland, and larger sample sizes will be necessary to detect risk variants.
High-throughput sequencing using pooled DNA samples can facilitate genome-wide studies on rare and low-frequency variants in a large population. Some major questions concerning the pooling sequencing ...strategy are whether rare and low-frequency variants can be detected reliably, and whether estimated minor allele frequencies (MAFs) can represent the actual values obtained from individually genotyped samples. In this study, we evaluated MAF estimates using three variant detection tools with two sets of pooled whole exome sequencing (WES) and one set of pooled whole genome sequencing (WGS) data. Both GATK and Freebayes displayed high sensitivity, specificity and accuracy when detecting rare or low-frequency variants. For the WGS study, 56% of the low-frequency variants in Illumina array have identical MAFs and 26% have one allele difference between sequencing and individual genotyping data. The MAF estimates from WGS correlated well (r = 0.94) with those from Illumina arrays. The MAFs from the pooled WES data also showed high concordance (r = 0.88) with those from the individual genotyping data. In conclusion, the MAFs estimated from pooled DNA sequencing data reflect the MAFs in individually genotyped samples well. The pooling strategy can thus be a rapid and cost-effective approach for the initial screening in large-scale association studies.
Pre-eclampsia is a common and complex pregnancy disorder that often involves impaired placental development. In order to identify altered gene expression in pre-eclamptic placenta, we sequenced ...placental transcriptomes of nine pre-eclamptic and nine healthy pregnant women in pools of three. The differential gene expression was tested both by including all the pools in the analysis and by excluding some of the pools based on phenotypic characteristics. From these analyses, we identified altogether 53 differently expressed genes, a subset of which was validated by qPCR in 20 cases and 19 controls. Furthermore, we conducted pathway and functional analyses which revealed disturbed vascular function and immunological balance in pre-eclamptic placenta. Some of the genes identified in our study have been reported by numerous microarray studies (
BHLHE40
,
FSTL3
,
HK2
,
HTRA4
,
LEP
,
PVRL4
,
SASH1
,
SIGLEC6
), but many have been implicated in only few studies or have not previously been linked to pre-eclampsia (
ARMS2
,
BTNL9, CCSAP
,
DIO2
,
FER1L4
,
HPSE
,
LOC100129345
,
LYN
,
MYO7B
,
NCMAP
,
NDRG1
,
NRIP1, PLIN2
,
SBSPON, SERPINB9, SH3BP5
,
TET3
,
TPBG
,
ZNF175
). Several of the molecules produced by these genes may have a role in the pathogenesis of pre-eclampsia, and some could qualify as biomarkers for prediction or detection of this pregnancy complication.
Introduction: Preeclampsia is a common and partially genetic pregnancy complication characterized by hypertension and proteinuria. Association with cardiovascular disease and type 2 diabetes has been ...reported in 9p21 by several genome-wide association studies. It has been hypothesized that cardiometabolic diseases may share common etiology with preeclampsia.
Materials and methods: We tested association with the 9p21 region to preeclampsia in the Finnish population by genotyping 23 tagging single nucleotide polymorphisms (SNPs) in 15 extended preeclampsia families and in a nationwide cohort consisting of 281 cases and 349 matched controls. Replication was conducted in additional datasets.
Results: Four SNPs (rs7044859, rs496892, rs564398 and rs7865618) showed nominal association (p ≤ 0.024 uncorrected) with preeclampsia in the case-control cohort. To increase power, we genotyped two SNPs in additional 388 cases and 341 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort. Partial replication was also attempted in a UK cohort (237 cases and 199 controls) and in 74 preeclamptic families from Australia/New Zealand. We were unable to replicate the initial association in the extended Finnish dataset or in the two international cohorts.
Conclusions: Our study did not find evidence for the involvement of the 9p21 region in the risk of preeclampsia.
Key Message
Chromosome 9p21 is not associated with preeclampsia.
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