Finnish Genetics Of Pre-eclampsia Consortium Research Articles

Fetal cord plasma herpesviruses and preeclampsia: an observational cohort study

A previous study suggested that fetal inheritance of chromosomally integrated human herpesvirus 6 (ici-HHV6) is associated with the hypertensive pregnancy disorder preeclampsia (PE). We aimed to study this question utilizing cord plasma samples (n = 1276) of the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort: 539 from a pregnancy with PE and 737 without. We studied these samples and 30 placentas from PE pregnancies by a multiplex qPCR for the DNAs of all nine human herpesviruses. To assess the population prevalence of iciHHV-6, we studied whole-genome sequencing data from blood-derived DNA of 3421 biobank subjects. Any herpes viral DNA was detected in only two (0.37%) PE and one (0.14%) control sample (OR 2.74, 95% CI 0.25–30.4). One PE sample contained iciHHV-6B and another HHV-7 DNA. The control’s DNA was of iciHHV-6B; the fetus having growth restriction and preterm birth without PE diagnosis. Placentas showed no herpesviruses. In the biobank data, 3 of 3421 subjects (0.08%) had low level HHV-6B but no iciHHV-6. While iciHHV-6 proved extremely rare, both fetuses with iciHHV-6B were growth-restricted, preterm, and from a pregnancy with maternal hypertension. Our findings suggest that human herpesviruses are not a significant cause of PE, whereas iciHHV-6 may pose some fetal risk.

Impact of physical activity on preeclampsia and angiogenic markers in the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort

Introduction Effect of physical activity in pregnancy on preeclampsia (PE) and angiogenic markers is not well understood. We studied the association of physical activity and PE in a case-control setting and assessed whether exercise in PE and non-PE women associate with maternal serum concentrations of soluble fms-like tyrosine kinase 1 (s-Flt-1), placental growth factor (PlGF) and soluble endoglin (sEng) and sFlt-1/PlGF ratio in the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort. Materials and methods Participants completed a questionnaire on their background information and serum samples were collected from a subset. Questionnaire data on physical activity were available from 708 PE women and 724 non-PE women. Both first trimester serum samples and questionnaire data on physical activity were available from 160 PE women and 160 non-PE women, and second/third trimester serum samples and questionnaire data on physical activity were available from 139 PE women and 47 non-PE women. The PE and non-PE women were divided into categories of physically active (exercise 2 − 3 times/week or more) and physically inactive (exercise less than 2 − 3 times/week). Results A total of 43.4% of the PE women and 42.4% of the non-PE women were categorized as physically active. There were no differences in physical activity and exercise habits between the groups. The physically active women were more often nulliparous and non-smokers and had a lower body mass index. There were no differences in the concentrations of angiogenic markers (sFlt-1, PlGF and sEng and sFlt-1/PlGF ratio) between the groups who exercised more or less than 2 − 3 times/week. Conclusions In the FINNPEC study cohort, there was no association between physical activity and PE and no associations of physical activity in pregnant women with and without PE with maternal serum concentrations of sFlt-1, PlGF and sEng and sFlt-1/PlGF ratio.

Validation of the Finnish Care register for Health Care diagnoses for preeclampsia, gestational diabetes and preterm delivery

BackgroundCentrally collected Finnish national health register data on adverse pregnancy outcomes are available for research, but the validity of the data is largely unknown. Our aim was to compare the diagnoses of preeclampsia (PE), gestational diabetes (GDM), and preterm delivery from hospital records with the registry based diagnoses from the Finnish Care Register for Health Care (FCR). Data on gestational age at delivery from the Medical Birth Registry (MBR) was also studied. MethodsThe Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) Study cohort was used as a data source. Each diagnosis was ascertained from electronic hospital records. The validity of diagnoses obtained by record linkage of FCR and MBR was assessed against the classification previously confirmed independently by a research nurse and a study physician. ResultsSensitivity of PE diagnoses in FCR was 80.3 % (95 % CI 78.3 % to 82.2 %) andspecificity 95.3 % (95 % CI 93.9 % to 96.4 %). Sensitivity for GDM was 64.1 % (95 % CI: 58.7 % − 69.3 %) and specificity 98.5 % (95 % CI: 97.9 % − 98.9 %), whereas sensitivity and specificity for preterm delivery were 32.4 % (95 % CI: 29.0 % − 36.0 %) and 99.7 % (95 % CI: 99.3 % − 99.9 %). Sensitivity of preterm delivery in the MBR was 99.1 % and specificity 99.9 %. ConclusionsFCR registry diagnoses for PE have satisfactory sensitivity and high specificity. Diagnoses for GDM and preterm delivery have lower sensitivity limiting their use in studies, and data from MBR should be preferred when studying preterm deliveries.

Genetic Risk Factors Associated With Preeclampsia and Hypertensive Disorders of Pregnancy

A genetic contribution to preeclampsia susceptibility has been established but is still incompletely understood. To disentangle the underlying genetic architecture of preeclampsia and preeclampsia or other maternal hypertension during pregnancy with a genome-wide association study (GWAS) of hypertensive disorders of pregnancy. This GWAS included meta-analyses in maternal preeclampsia and a combination phenotype encompassing maternal preeclampsia and preeclampsia or other maternal hypertensive disorders. Two overlapping phenotype groups were selected for examination, namely, preeclampsia and preeclampsia or other maternal hypertension during pregnancy. Data from the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC, 1990-2011), Finnish FinnGen project (1964-2019), Estonian Biobank (1997-2019), and the previously published InterPregGen consortium GWAS were combined. Individuals with preeclampsia or other maternal hypertension during pregnancy and control individuals were selected from the cohorts based on relevant International Classification of Diseases codes. Data were analyzed from July 2020 to February 2023. The association of a genome-wide set of genetic variants and clinical risk factors was analyzed for the 2 phenotypes. A total of 16 743 women with prior preeclampsia and 15 200 with preeclampsia or other maternal hypertension during pregnancy were obtained from FINNPEC, FinnGen, Estonian Biobank, and the InterPregGen consortium study (respective mean [SD] ages at diagnosis: 30.3 [5.5], 28.7 [5.6], 29.7 [7.0], and 28 [not available] years). The analysis found 19 genome-wide significant associations, 13 of which were novel. Seven of the novel loci harbor genes previously associated with blood pressure traits (NPPA, NPR3, PLCE1, TNS2, FURIN, RGL3, and PREX1). In line with this, the 2 study phenotypes showed genetic correlation with blood pressure traits. In addition, novel risk loci were identified in the proximity of genes involved in the development of placenta (PGR, TRPC6, ACTN4, and PZP), remodeling of uterine spiral arteries (NPPA, NPPB, NPR3, and ACTN4), kidney function (PLCE1, TNS2, ACTN4, and TRPC6), and maintenance of proteostasis in pregnancy serum (PZP). The findings indicate that genes related to blood pressure traits are associated with preeclampsia, but many of these genes have additional pleiotropic effects on cardiometabolic, endothelial, and placental function. Furthermore, several of the associated loci have no known connection with cardiovascular disease but instead harbor genes contributing to maintenance of successful pregnancy, with dysfunctions leading to preeclampsialike symptoms.

Searching for a paternal phenotype for preeclampsia

AbstractIntroductionPreeclampsia (PE) is a heterogeneous disorder and research to date has principally focused on maternal factors. In this study, however, we considered the associations between background factors and preeclampsia in men who fathered preeclamptic and non‐preeclamptic pregnancies.Material and methodsFrom 2008 to 2011, participants in the Finnish Genetics of Pre‐eclampsia Consortium (FINNPEC) cohort completed a questionnaire on their background information. Questionnaire data were available from 586 men who had fathered a preeclamptic pregnancy (PE fathers) and 660 control men who had fathered a non‐preeclamptic pregnancy. Two different control groups were established: Group 1: healthy controls (n = 457), which consisted of fathers whose current partners were healthy women with uncomplicated pregnancies; Group 2: other controls (n = 203), which also included fathers whose current partners had other pregnancy complications.ResultsThe PE fathers more often reported preeclampsia in a previously fathered pregnancy (p < 0.05 for all). The PE and control fathers were similar in age, body mass index, smoking, and preexisting medical conditions. There were no differences in the socioeconomic background or health history of the PE and control fathers or their parents.ConclusionsIn the FINNPEC study cohort, the occurrence of preeclampsia in a previously fathered pregnancy was more common among the men who had fathered a preeclamptic pregnancy; other paternal phenotypic and lifestyle characteristics did not play a significant role in preeclampsia susceptibility of their partners.

Increased Risk of Preeclampsia in Women With a Genetic Predisposition to Elevated Blood Pressure.

Background:Preeclampsia causes significant maternal and perinatal morbidity. Genetic factors seem to affect the onset of the disease. We aimed to investigate whether the polygenic risk score for blood pressure (BP; BP-PRS) is associated with preeclampsia, its subtypes, and BP values during pregnancy.Methods:The analyses were performed in the FINNPEC study (Finnish Genetics of Pre-Eclampsia Consortium) cohort of 1514 preeclamptic and 983 control women. In a case-control setting, the data were divided into percentiles to compare women with high BP-PRS (HBP-PRS; >95th percentile) or low BP-PRS (≤5th percentile) to others. Furthermore, to evaluate the effect of BP-PRS on BP, we studied 3 cohorts: women with preeclampsia, hypertensive controls, and normotensive controls.Results:BP values were higher in women with HBP-PRS throughout the pregnancy. Preeclampsia was more common in women with HBP-PRS compared with others (71.8% and 60.1%, respectively; P=0.009), and women with low BP-PRS presented with preeclampsia less frequently than others (44.8% and 61.5%, respectively; P<0.001). HBP-PRS was associated with an increased risk for preeclampsia (odds ratio, 1.7 [95% CI, 1.1–2.5]). Furthermore, women with HBP-PRS presented with recurrent preeclampsia and preeclampsia with severe features more often.Conclusions:Our results suggest that HBP-PRS is associated with an increased risk of preeclampsia, recurrent preeclampsia, and preeclampsia with severe features. Furthermore, women with HBP-PRS present higher BP values during pregnancy. The results strengthen the evidence pointing toward the role of genetic variants associated with BP regulation in the etiology of preeclampsia, especially its more severe forms.

A non-targeted LC\u2013MS metabolic profiling of pregnancy: longitudinal evidence from healthy and pre-eclamptic pregnancies

IntroductionMaternal metabolism changes substantially during pregnancy. However, few studies have used metabolomics technologies to characterize changes across gestation.Objectives and methodsWe applied liquid chromatography–mass spectrometry (LC–MS) based non-targeted metabolomics to determine whether the metabolic profile of serum differs throughout the pregnancy between pre-eclamptic and healthy women in the FINNPEC (Finnish Genetics of Preeclampsia Consortium) Study. Serum samples were available from early and late pregnancy.ResultsProgression of pregnancy had large-scale effects to the serum metabolite profile. Altogether 50 identified metabolites increased and 49 metabolites decreased when samples of early pregnancy were compared to samples of late pregnancy. The metabolic signatures of pregnancy were largely shared in pre-eclamptic and healthy women, only urea, monoacylglyceride 18:1 and glycerophosphocholine were identified to be increased in the pre-eclamptic women when compared to healthy controls.ConclusionsOur study highlights the need of large-scale longitudinal metabolomic studies in non-complicated pregnancies before more detailed understanding of metabolism in adverse outcomes could be provided. Our findings are one of the first steps for a broader metabolic understanding of the physiological changes caused by pregnancy per se.

The non-traditional and familial risk factors for preeclampsia in the FINNPEC cohort.

Considering the burden of preeclampsia (PE), it is important to understand better the underlying risk factors involved in its etiology. We studied the association of background factors with PE with an emphasis on socioeconomic factors, reproductive factors and health history enclosing the parents of pregnant women. The Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort participants filled in a questionnaire on background information. The questionnaire data was available from 708 women with PE and 724 control women. Two different control groups, healthy controls with uncomplicated pregnancies (n=498) and all controls (n=724, including controls with uncomplicated pregnancies and pregnancy complications other than PE), were established. PE women had similar socioeconomic status and more often non-communicable diseases including type 1 diabetes, chronic hypertension and hyperlipidemia than the two control groups (p<0.05 for all). Depression and subfertility were more common among PE women and they had earlier menarche (p<0.05 for all). Hypertension was more common in both parents of PE women, stroke in fathers and diabetes in mothers (p<0.05 for all). Mental disorders including depression were more common in mothers of PE women compared to controls (PE women 7.2%, healthy controls 3.7% (p=0.013) and all controls 3.9% (p=0.007)). In the FINNPEC cohort, PE women had similar socioeconomic status, more non-communicable diseases and depression, earlier menarche, more subfertility and more parental non-communicable diseases compared to controls. As a novel finding we found more mental disorders including depression in mothers of PE women.

Impact of obesity on angiogenic and inflammatory markers in the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) cohort

While several studies have demonstrated that obesity increases the risk of pre-eclampsia (PE), the mechanisms have yet to be elucidated. We assessed the association between maternal/paternal obesity and PE and hypothesized that maternal body mass index (BMI) would be associated with an adverse inflammatory and angiogenic profile. High-sensitivity C-reactive protein (hs-CRP) and following serum angiogenic markers were determined: soluble endoglin (sEng), soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF). Data on BMI were available from 1450 pregnant women with PE and 1065 without PE. Serum concentrations of hs-CRP and angiogenic markers were available from a subset at first and third trimesters. Prepregnancy BMI was higher in the PE group than in controls (mean ± SD) 25.3 ± 5.2 vs. 24.1 ± 4,4, p < 0.001, adjusted for parity, mother's age, and smoking status before pregnancy. Increased hs-CRP concentrations were observed in both PE and non-PE women similarly according to BMI category. In women with PE, a higher BMI was associated with lower sFlt-1 and sEng concentrations throughout the pregnancy (p = 0.004, p = 0.008, respectively). There were no differences in PlGF in PE women according to BMI. We confirmed increased pre-pregnancy BMI in women with PE. Enhanced inflammatory state was confirmed in all women with overweight/obesity. Partly paradoxically we observed that PE women with obesity had less disturbed levels of angiogenic markers than normal weight women with PE. This should be taken into account when angiogenic markers are used in PE prediction.

Angiogenic profile in the Finnish Genetics of Pre-Eclampsia Consortium (FINNPEC) cohort.

To study first and second/third trimester levels of soluble fms-like tyrosine kinase 1 (sFlt1), placental growth factor (PlGF) and soluble endoglin (sEng) in FINNPEC case-control cohort. The participants were further divided into subgroups based on parity and onset of the disease. Recommended cut-off values in aid of pre-eclampsia (PE) prediction and diagnosis were also tested. First trimester serum samples were available from 221 women who later developed PE and 239 women who did not develop PE. Second/third trimester serum samples were available from 175 PE and 55 non-PE women. sFlt-1 and PlGF were measured electro-chemiluminescence immunoassays and sEng by ELISA. In all timepoints PlGF, endoglin and the sFlt-1/PlGF ratio were increased in the PE group compared to the non-PE group. The serum concentrations of sFlt-1 were increased only at second/third trimester in PE women. Higher concentrations of s-Flt1, endoglin and higher sFlt/PlGF ratio were found at the third trimester in primiparous women compared to multiparous women. Primiparous PE women also had lower concentrations of PlGF at the third trimester. The proportion of women exceeding all cut-offs of the sFlt-1/PlGF ratio (≥33, ≥38, ≥85 and ≥110) was greater in the PE group, but there were also pre-eclamptic women who met rule-out cut-off or did not meet rule-in cut-off. Primiparous pregnancies have more anti-angiogenic profile during second/third trimester compared with multiparous pregnancies. Our findings also suggest that certain maternal characteristics, e.g. BMI, smoking and pre-existing diseases, should be taken into account when different sFlt-1/PlGF ratio cut-offs are utilized.

Protective Low-Frequency Variants for Preeclampsia in the Fms Related Tyrosine Kinase 1 Gene in the Finnish Population.

Preeclampsia is a common pregnancy-specific vascular disorder characterized by new-onset hypertension and proteinuria during the second half of pregnancy. Predisposition to preeclampsia is in part heritable. It is associated with an increased risk of cardiovascular disease later in life. We have sequenced 124 candidate genes implicated in preeclampsia to pinpoint genetic variants contributing to predisposition to or protection from preeclampsia. First, targeted exomic sequencing was performed in 500 preeclamptic women and 190 controls from the FINNPEC cohort (Finnish Genetics of Preeclampsia Consortium). Then 122 women with a history of preeclampsia and 1905 parous women with no such history from the National FINRISK Study (a large Finnish population survey on risk factors of chronic, noncommunicable diseases) were included in the analyses. We tested 146 rare and low-frequency variants and found an excess (observed 13 versus expected 7.3) nominally associated with preeclampsia (P<0.05). The most significantly associated sequence variants were protective variants rs35832528 (E982A; P=2.49E-4; odds ratio=0.387) and rs141440705 (R54S; P=0.003; odds ratio=0.442) in Fms related tyrosine kinase 1. These variants are enriched in the Finnish population with minor allele frequencies 0.026 and 0.017, respectively. They may also be associated with a lower risk of heart failure in 11 257 FINRISK women. This study provides the first evidence of maternal protective genetic variants in preeclampsia.

Angiogenic profile and smoking in the Finnish Genetics of Pre-Eclampsia Consortium (FINNPEC) cohort

Objectives: The biological mechanism by which smoking reduces the risk of pre-eclampsia (PE) is unresolved. We studied serum levels of soluble fms-like tyrosine kinase 1 (sFlt-1), placental growth factor (PlGF) and their ratio, in addition to soluble endoglin (sEng) in early and late pregnancy to ascertain whether these factors are altered in women who smoke.Subjects and methods: First trimester serum samples were available from 217 women who later developed PE and 238 women who did not develop PE. Second/third trimester serum samples were available from 174 PE and 54 non-PE women.Results: PE women who smoked during pregnancy had elevated first trimester concentrations of serum PlGF [geometric mean (95% CI): 39.8 (32.6–48.5) pg/ml, p = .001] and reduced sEng concentration [5.0 (4.6–5.6) ng/ml, p = .047] compared to PE non-smokers [30.0 (28.1–32.1) pg/ml and 6.1 (5.9–6.4) ng/ml, respectively]. Non-smoking women in the PE group had the highest sFlt-1/PlGF ratio in early and late pregnancy.Conclusions: The protective effect of smoking in reducing the risk of PE may be due to the early pregnancy change towards pro-angiogenic marker profile. Also, in late pregnancy, smoking exerted effect in sFlt-1/PlGF ratio in PE pregnancies, and may complicate its use as a prognostic and diagnostic marker.Key messagesSmoking appears to have angiogenic effects in early pregnancy with reduced sEng concentrations and elevated PlGF concentrations in both normal and PE pregnancies.Throughout pregnancy, smoking exerted effect in PlGF concentration and sFlt-1/PlGF ratio in PE pregnancies, and thus may complicate its use as a prognostic and diagnostic marker.

Cohort profile: the Finnish Genetics of Pre-eclampsia Consortium (FINNPEC)

PurposeThe Finnish Genetics of Pre-eclampsia Consortium (FINNPEC) Study was established to set up a nationwide clinical and DNA database on women with and without pre-eclampsia (PE), including their partners and...

Stanniocalcin-1 Hormone in Nonpreeclamptic and Preeclamptic Pregnancy: Clinical, Life-Style, and Genetic Modulators.

Context and Objectives:The study represents the first comprehensive analysis of Stanniocalcin-1 (STC1) hormone in human pregnancy, assessing clinical, lifestyle, and genetic determinants of circulating STC1 at term.Design, Setting, and Participants:Participants included women with (n = 50) and without (n = 316) preeclampsia (PE) at delivery, recruited in the REPROgrammed fetal and/or maternal METAbolism (REPROMETA) study (2006–2011, Estonia). Genetic association analysis combined PE cases (n = 597) and controls (n = 623) from the REPROMETA and Finnish Genetics of Preeclampsia Consortium (2008–2011) studies.Main Outcome Measure(s):Maternal postpartum plasma STC1 was measured by ELISA (n = 366) and placental STC1 gene expression by TaqMan quantitative RT-PCR (n = 120). Genotyping was performed using Sequenom MassArray.Results:Significantly higher STC1 plasma level was measured for the PE (median, 1952 pg/mL; 1030–4284 pg/mL) compared with non-PE group (median, 1562 pg/mL; 423–3781 pg/mL; P = 3.7 × 10−4, Mann-Whitney U test). Statistical significance was enhanced after adjustment for cofactors (linear regression, P = 1.8 × 10−6). STC1 measurements were negatively correlated with maternal smoking. Prepregnancy body mass index had a positive correlation with STC1 only among PE patients (r = 0.45; P = .001). The strongest genetic association with hormone concentrations was detected for STC1 single nucleotide polymorphisms rs3758089 (C allele: minor allele frequency, 5%; linear regression: β = 249.2 pg/mL; P = .014) and rs12678447 (G allele: minor allele frequency, 7%; β = 147.0 pg/mL; P = .082). rs12678447 placental genotypes were significantly associated with STC1 gene expression (P = .014). The REPROMETA/Finnish Genetics of Preeclampsia Consortium meta-analysis suggested an increased risk to develop late-onset PE for the rs12678447 G allele carriers (P = .05; odds ratio = 1.38 [0.98–1.93]).Conclusions:Increased STC1 hormone represents a hallmark of late-onset PE. STC1 gene variants modulate placental gene expression and maternal hormone levels.

An RGS2 3'UTR polymorphism is associated with preeclampsia in overweight women.

BackgroundPreeclampsia is a common and heterogeneous vascular syndrome of pregnancy. Its genetic risk profile is yet unknown and may vary between individuals and populations. The rs4606 3′ UTR polymorphism of the Regulator of G-protein signaling 2 gene (RGS2) in the mother has been implicated in preeclampsia as well as in the development of chronic hypertension after preeclampsia. The RGS2 protein acts as an inhibitor of physiological vasoconstrictive pathways, and a low RGS2 level is associated with hypertension and obesity, two conditions that predispose to preeclampsia. We genotyped the rs4606 polymorphism in 1339 preeclamptic patients and in 697 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort to study the association of the variant with preeclampsia.ResultsNo association between rs4606 and preeclampsia was detected in the analysis including all women. However, the polymorphism was associated with preeclampsia in a subgroup of overweight women (body mass index ≥ 25 kg/m2, and < 30 kg/m2) (dominant model; odds ratio, 1.64; 95 % confidence interval, 1.10–2.42).ConclusionsOur results suggest that RGS2 might be involved in the pathogenesis of preeclampsia particularly in overweight women and contribute to their increased risk for hypertension and other types of cardiovascular disease later in life.

Preeclampsia does not share common risk alleles in 9p21 with coronary artery disease and type 2 diabetes

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 MessageChromosome 9p21 is not associated with preeclampsia.

Microsatellite polymorphism in the heme oxygenase-1 promoter is associated with nonsevere and late-onset preeclampsia.

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 model: odds ratio [OR], 1.94; 95% confidence interval [CI], 1.13-3.31; recessive model: OR, 1.39; 95% CI, 1.02-1.89) and late-onset (additive model: OR, 1.44; 95% CI, 1.02-2.05; recessive model: OR, 1.28; 95% CI, 1.02-1.59) preeclampsia and with preeclampsia without a small-for-gestational-age infant (recessive model: OR, 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.