Maternal hypertensive traits and adverse outcome in pregnancy: a Mendelian randomization study.

INTRODUCTION: Hypertensive disorders of pregnancy are associated with adverse feto-maternal outcomes. Existing evidence is mostly limited to observational studies, which are liable to confounding and bias. This study investigated the causal relevance of component hypertensive indices on multiple adverse pregnancy outcomes using Mendelian randomization. METHODS: Uncorrelated ( r2  < 0.001) genome-wide significant ( P  < 5 × 10 -8 ) single-nucleotide polymorphisms associated with SBP, DBP and pulse pressure (PP) were selected as instrumental variables. Genetic association estimates for outcomes of preeclampsia or eclampsia, preterm birth, placental abruption and hemorrhage in early pregnancy were extracted from summary statistics of genome-wide association studies in the FinnGen cohort. Two-sample, inverse-variance weighted Mendelian randomization formed the primary analysis method. Odds ratios (OR) are presented per-10 mmHg higher genetically predicted hypertensive index. RESULTS: Higher genetically predicted SBP were associated with higher odds of preeclampsia or eclampsia [OR 1.81, 95% confidence interval (CI) 1.68-1.96, P  = 5.45 × 10 -49 ], preterm birth (OR 1.09, 95% CI 1.03-1.16, P  = 0.005) and placental abruption (OR 1.33, 95% CI 1.05-1.68, P  = 0.016). Higher genetically-predicted DBP was associated with preeclampsia or eclampsia (OR 2.54, 95% CI 2.21-2.92, P  = 5.35 × 10 -40 ). Higher genetically predicted PP was associated with preeclampsia or eclampsia (OR 1.68, 95% CI 1.47-1.92, P  = 1.9 × 10 -14 ) and preterm birth (OR 1.18, 95% CI 1.06-1.30, P  = 0.002). CONCLUSION: This study provides genetic evidence to support causal associations of SBP, DBP and PP on multiple adverse outcomes of pregnancy. SBP and PP were associated with the broadest range of adverse outcomes, suggesting that optimized management of blood pressure, particularly SBP, is a key priority to improve feto-maternal health.

Maternal-fetal genetic interactions, imprinting, and risk of placental abruption.

RESULTS: Abruption cases were more likely to experience preeclampsia, have shorter gestational age, and deliver infants with lower birthweight compared with controls. Models with MFGI effects provided improved fit than models with only maternal and fetal genotype main effects for SNP rs12530904 (p-value = 1.2e-04) in calcium/calmodulin-dependent protein kinase [CaM kinase] II beta (CAMK2B), and, SNP rs73136795 (p-value = 1.9e-04) in peroxisome proliferator-activated receptor-gamma (PPARG), both MB genes. We identified 320 SNPs in 45 maternally-imprinted genes (including potassium voltage-gated channel subfamily Q member 1 [KCNQ1], neurotrimin [NTM], and, ATPase phospholipid transporting 10 A [ATP10A]) associated with abruption. Top hits included rs2012323 (p-value = 1.6E-16) and rs12221520 (p-value1.3e-13) in KCNQ1, rs8036892 (p-value = 9.3E-17) and rs188497582 in ATP10A, rs12589854 (p-value = 2.9E-11) and rs80203467 (p-value = 4.6e-11) in maternally expressed 8, small nucleolar RNA host (MEG8), and rs138281088 in solute carrier family 22 member 2 (SLC22A2) (p-value = 6.8e-9). CONCLUSIONS: We identified novel PA-related maternal-fetal MB gene interactions and imprinting effects that highlight the role of the fetus in PA risk development. Findings can inform mechanistic investigations to understand the pathogenesis of PA.

Association of MTHFR 677C>T polymorphism with IUGR and placental abruption risk: A systematic review and meta-analysis.

OBJECTIVE: The effects of the MTHFR 677C > T polymorphism on the intrauterine growth restriction (IUGR) and placental abruption risk have been evaluated in some studies. However, those studies results were conflicting and ambiguous. Therefore, we carried out the current meta-analysis to evaluate the association of MTHFR 677C > T polymorphism with risk of IUGR and placental abruption from all eligible studies. METHODS: An electronic search of the PubMed, Embase, Scopus and CNKI databases was performed up to February 25, 2020. RESULTS: A total of 25 case-control studies including eight studies with 687 cases and 2336 controls for IUGR and 17 studies with 1574 cases and 5758 controls for placental abruption were selected. The analysis results indicated that MTHFR 677C > T polymorphism was associated with an increased risk of IUGR and placental abruption in global population. When stratified by ethnicity a significant association between the MTHFR 677C > T polymorphism and IUGR risk was found in Caucasians and Africans. However, there was no a significant association between the MTHFR 677C > T polymorphism and placental abruption risk by ethnicity. CONCLUSIONS: Our pooled data indicated that the MTHFR 677C > T polymorphism might play a role in development of IUGR and placental abruption.

Genetic Polymorphisms Implicated in Major Pregnancy Complications: a Review.

Pregnancy short- or long-term complications may involve the mother's health, the fetus's health, or both. A systematic literature review was performed, including studies up to October 2018 from Medline (PubMed), Science Direct, Web of Science and Google Scholar. The following inclusion criteria were applied: studies published until 2018 concerning the genetic background of pregnancy complications such as high blood pressure, gestational diabetes, preeclampsia, pregnancy loss, endometrial death, placental abruption, premature labor, and intrauterine growth retardation which may render pregnancy a high risk condition.We identified 164 articles that met the inclusion criteria and reviewed and analyzed them. The results so far are contradictory and the pathogenicity of these pregnancy complications remains unclear. For most of the polymorphisms studied so far, data refer to small studies size but research is on-going.The identification of genetic polymorphisms with strong correlations with certain pregnancy complications could provide us with useful tools which could be incorporated in diagnostic algorithms that could facilitate early detection and treatment of major pregnancy complications.

Genetic risk assessment of thrombophilia in patients with adverse obstetric outcomes.

OBJECTIVES: To investigate the incidence of inherited thrombophilias in patients with adverse obstetric outcomes and to compare detection rates of thrombophilias between standard blood tests and a novel genetic test. METHODS: This is a case-control prospective study performed in Hospital Sant Joan de Déu in Barcelona, Spain. Cases had a history of intrauterine growth restriction requiring delivery before 34 weeks gestation, placental abruption before 34 weeks gestation, or severe preeclampsia. Controls had at least two normal, spontaneously conceived pregnancies at term, without complications or no underlying medical disease. At least 3 months after delivery, all case and control women underwent blood collection for standard blood tests for thrombophilias and saliva collection for the genetic test, which enables the diagnosis of 12 hereditary thrombophilias by analyzing genetic variants affecting different points of the blood coagulation cascade. RESULTS: The study included 33 cases and 41 controls. There were no statistically significant differences between cases and controls in the standard blood tests for thrombophilias in plasma or the TiC test for genetic variables. One clinical-genetic model was generated using variables with the lowest P values: ABO, body mass index, C_rs5985, C_rs6025, and protein S. This model exhibited good prediction capacity, with an area under the curve of almost 0.7 (P <0.05), sensitivity of almost 67%, and specificity of 70%. CONCLUSION: Although some association may exist between hypercoagulability and pregnancy outcomes, no significant direct correlation was observed between adverse obstetric outcomes and inherited thrombophilias when analyzed using either standard blood tests or the genetic test. Future studies with a larger sample size are required to create a clinical-genetic model that better discriminates women with a history of adverse pregnancy outcomes and an increased risk of poor outcomes in subsequent pregnancies.

Risk of Ischemic Placental Disease in Relation to Family History of Preeclampsia.

OBJECTIVE: To assess the risk of ischemic placental disease (IPD) including preeclampsia, small for gestational age (SGA), and abruption, in relation to preeclampsia in maternal grandmother, mother, and sister(s). STUDY DESIGN: We performed a secondary analysis of data from a randomized trial of vitamins C and E for preeclampsia prevention. Data on family history of preeclampsia were based on recall by the proband. The associations between family history of preeclampsia and the odds of IPD were evaluated from alternating logistic regressions. RESULTS: Of the 9,686 women who delivered nonmalformed, singleton live births, 17.1% had IPD. Probands provided data on preeclampsia in 55.5% (n = 5,374) on all three family members, 26.5% (n = 2,562) in mother and sister(s) only, and 11.6% (n = 1,125) in sister(s) only. The pairwise odds ratio (pOR) of IPD was 1.16 (95% confidence interval [CI]: 1.00-1.36) if one or more of the female relatives had preeclampsia. The pORs of preeclampsia were 1.54 (95% CI: 1.12-2.13) and 1.35 (95% CI: 1.03-1.77) if the proband's mother or sister(s) had a preeclamptic pregnancy, respectively, but no associations were seen for SGA infant or abruption. CONCLUSION: This study suggests that IPD may share a predisposition with preeclampsia, suggesting a familial inheritance.

Placenta-mediated pregnancy complications are not associated with fetal or paternal factor V Leiden mutation.

OBJECTIVE: Maternal thrombophilia is a risk factor for adverse pregnancy outcomes. The aim of this study was to elucidate the controversial role of fetal and paternal thrombophilia in the development of severe placenta-mediated pregnancy complications. STUDY DESIGN: The study group comprised 126 mothers, 72 fetuses and 58 fathers. 111 mothers, 50 fetuses and 91 fathers acted as controls. 106 couples were selected to study the thrombophilias of paternal inheritance, 58 from the study group and 48 from the control group. The prevalence of factor V Leiden mutation, prothrombin G20210 A mutation and homozygous 10-methylenetetrahydrofolate reductase C677 T mutations were compared between the study and control groups to study whether maternal, fetal or paternal thrombophilias increase the risk of severe preeclampsia, intrauterine growth restriction, placental abruption and stillbirth. RESULTS: The total prevalence of fetal thrombophilic mutations was 8.3% in the study group and 14.0% in the control group. Paternal prevalence of thrombophilic mutations was 6.8% and 4.3%, respectively. There were no statistical differences between fetal or paternal thrombophilic mutations between the study and control groups. CONCLUSION: Fetal or paternal factor V Leiden mutation is not associated with severe placenta-mediated pregnancy complications.

Abruptio placentae risk and genetic variations in mitochondrial biogenesis and oxidative phosphorylation: replication of a candidate gene association study.

BACKGROUND: Abruptio placentae is a complex multifactorial disease that is associated with maternal and neonatal death and morbidity. Abruptio placentae's high recurrence rate, high prevalence of heritable thrombophilia among women with abruptio placentae, and aggregation of cases in families of women with the disease support the possibility of a genetic predisposition. Previous genome-wide and candidate gene association studies have identified single nucleotide polymorphisms in mitochondrial biogenesis and oxidative phosphorylation genes that potentially are associated with abruptio placentae risk. Perturbations in mitochondrial biogenesis and oxidative phosphorylation, which results in mitochondrial dysfunction, can lead to the impairment of differentiation and invasion of the trophoblast and to several obstetrics complications that include abruptio placentae. OBJECTIVE: The purpose of this study was to determine whether the results of a candidate genetic association study that indicated a link between DNA variants (implicated in mitochondrial biogenesis and oxidative phosphorylation) and abruptio placentae could be replicated. STUDY DESIGN: The study was conducted among participants (507 abruptio placentae cases and 1090 control subjects) of the Placental Abruption Genetic Epidemiology study. Weighted genetic risk scores were calculated with the use of abruptio placentae risk-increasing alleles of 11 single nucleotide polymorphisms in 9 mitochondrial biogenesis and oxidative phosphorylation genes (CAMK2B, NR1H3, PPARG, PRKCA, THRB, COX5A, NDUFA10, NDUFA12, and NDUFC2), which previously was reported in the Peruvian Abruptio Placentae Epidemiology study, a study with similar design and study population to the Placental Abruption Genetic Epidemiology study. Logistic regression models were fit to examine associations of weighted genetic risk scores (quartile 1, <25th percentile; quartile 2, 25-50th percentile; quartile 3, 50-70th percentile, and quartile 4, >75th percentile) with risk of abruptio placentae, adjusted for population admixture (the first 4 principal components), maternal age, infant sex, and preeclampsia. The weighted genetic risk score was also modeled as a continuous predictor. To assess potential effect modification, analyses were repeated among strata that were defined by preeclampsia status, maternal age (≥35 vs 18-34 years), and infant sex. RESULTS: Abruptio placentae cases were more likely to have preeclampsia, shorter gestational age, and lower infant birthweight. Participants in quartile 2 (score, 12.6-13.8), quartile 3 (score, 13.9-15.0) and quartile 4 (score, ≥15.1) had a genetic risk score of 1.45-fold (95% confidence interval, 1.04-2.02; P=.03), a 1.42-fold (95% confidence interval, 1.02-1.98; P=.04), and a 1.75-fold (95% confidence interval, 1.27-2.42; P=7.0E-04) higher odds of abruptio placentae, respectively, compared with those in quartile 1 (score,<12.6; P-for trend=.0003). The risk of abruptio placentae was 1.12-fold (95% confidence interval, 1.05-1.19; P=3.0×1004) higher per 1-unit increase in the score. Among women with preeclampsia, those in quartile 4 had a 3.92-fold (95% confidence interval, 1.48-10.36; P=.01) higher odds of abruptio placentae compared with women in quartile 1. Among normotensive women, women in quartile 4 had a 1.57-fold (95% confidence interval, 1.11-2.21; P=.01) higher odds of abruptio placentae compared with those in quartile 1 (P-for interaction=.12). We did not observe differences in associations among strata defined by maternal age or infant sex. CONCLUSION: In this study, we replicated previous findings and provide strong evidence for DNA variants that encode for genes that are involved in mitochondrial biogenesis and oxidative phosphorylation pathways, which confers risk for abruptio placentae. These results shed light on the mechanisms that implicate DNA variants that encode for proteins in mitochondrial function that are responsible for abruptio placentae risk. Therapeutic efforts to reduce risk of abruptio placentae can be enhanced by improved biologic understanding of maternal mitochondrial biogenesis/oxidative phosphorylation pathways and identification of women who would be at high risk for abruptio placentae.

Genetic variations and risk of placental abruption: A genome-wide association study and meta-analysis of genome-wide association studies.

INTRODUCTION: Accumulating epidemiological evidence points to strong genetic susceptibility to placental abruption (PA). However, characterization of genes associated with PA remains incomplete. We conducted a genome-wide association study (GWAS) of PA and a meta-analysis of GWAS. METHODS: Participants of the Placental Abruption Genetic Epidemiology (PAGE) study, a population based case-control study of PA conducted in Lima, Peru, were genotyped using the Illumina HumanCore-24 BeadChip platform. Genotypes were imputed using the 1000 genomes reference panel, and >4.9 million SNPs that passed quality control were analyzed. We performed a GWAS in PAGE participants (507 PA cases and 1090 controls) and a GWAS meta-analysis in 2512 participants (959 PA cases and 1553 controls) that included PAGE and the previously reported Peruvian Abruptio Placentae Epidemiology (PAPE) study. We fitted population stratification-adjusted logistic regression models and fixed-effects meta-analyses using inverse-variance weighting. RESULTS: Independent loci (linkage-disequilibrium<0.80) suggestively associated with PA (P-value<5e-5) included rs4148646 and rs2074311 in ABCC8, rs7249210, rs7250184, rs7249100 and rs10401828 in ZNF28, rs11133659 in CTNND2, and rs2074314 and rs35271178 near KCNJ11 in the PAGE GWAS. Similarly, independent loci suggestively associated with PA in the GWAS meta-analysis included rs76258369 near IRX1, and rs7094759 and rs12264492 in ADAM12. Functional analyses of these genes showed trophoblast-like cell interaction, as well as networks involved in endocrine system disorders, cardiovascular diseases, and cellular function. CONCLUSIONS: We identified several genetic loci and related functions that may play a role in PA risk. Understanding genetic factors underlying pathophysiological mechanisms of PA may facilitate prevention and early diagnostic efforts.

Desprendimiento prematuro de placenta normoinsertada por mutación heterocigota en el gen de la protrombina / Placental abruption associated with heterozygous prothrombin gene mutation

El desprendimiento prematuro de placenta se define como la separación parcial o completa de una placenta normalmente insertada antes del inicio del parto. Esto se produce en un 0,4-1% de las gestaciones. Esta patología se asocia a una elevada morbimortalidad materno-fetal. Existen distintos factores de riesgo asociados con el desprendimiento prematuro de placenta. Entre estos factores se encuentran: trastornos hipertensivos del embarazo, antecedentes de desprendimiento placentario o cesárea, diabetes, multiparidad, sobredistensión uterina (gestación múltiple o polihidramnios), rotura prematura de membranas, traumatismos abdominales, consumo de tóxicos y trombofilias. En un elevado número de casos la causa del desprendimiento es desconocida. El diagnóstico se basa fundamentalmente en las manifestaciones clínicas. El empleo de la ecografía tiene una utilidad muy limitada para el diagnóstico debido a su baja sensibilidad. La actitud va a estar condicionada por el estado materno y fetal, el grado de desprendimiento placentario y la edad gestacional en el momento del diagnóstico. Se presenta un caso clínico de un desprendimiento prematuro de placenta normoinsertada asociado a coagulación intravascular diseminada, útero de Couvelaire y atonía uterina debido a la mutación 620210 A heterocigota en el gen de la protrombina

Placental abruption defined as the complete or partial separation of a normally implanted placenta before delivery, occurs in 0.4-1%. It is one of the most significant causes of maternal and perinatal morbidity and mortality. The risk factor of abruption placentae are hypertension, prior caesarean delivery, previous abruption placentae, pregestational diabetes, high parity, polyhydramnion, multiple gestation, premature rupture of membranes, abdominal trauma, drug abuse and thrombophilia. The cause of placental abruption often remains unexplained. The diagnosis of placental abruption is clinical, based on characteristic signs and symptoms. Sonography is not sensitive for the detection of placental abruption. Prenatal and perinatal management depend on maternal and foetal condition, severity and gestational age. We report the case of placental abruption associated with disseminated intravascular coagulation, Couvelaire uterus and uterine atony. The patient was diagnosed with heterozygous prothrombin gene mutation 620210 A

Genetic variations related to maternal whole blood mitochondrial DNA copy number: a genome-wide and candidate gene study.

We conducted genome-wide (GWAS) and candidate gene association studies of maternal mitochondrial DNA copy number. Maternal peripheral blood was collected during labor and delivery admission from 471 participants of a placental abruption case-control study conducted in Lima, Peru. Single nucleotide polymorphism (SNP) genotyping was performed using the Illumina Cardio-Metabo Chip. Whole blood mitochondrial DNA (mtDNA) copy number was measured using qRT-PCR techniques. We evaluated 119,629 SNPs in the GWAS and 161 SNPs (in 29 mitochondrial biogenesis and oxidative phosphorylation genes) in the candidate association study. Top hits from GWAS and the candidate gene study were selected to compute weighted genetic risk scores (wGRS). Linear regression models were used to calculate effect size estimates and related nominal p values. The top hit in our GWAS was chr19:51063065 in FOXA3 (empirical p values = 2.20e - 6). A total of 134 SNPs had p values < 0.001 including rs17111633 in CNNM1 (p values = 6.32e - 6) and chr19:51083059 in MYPOP (p values = 3.23e - 5). In the candidate association study, several SNPs in PPARG, PRKCA, SP1 and THRB were associated with mtDNA copy number (p values < 0.05). mtDNA copy number was significantly associated with wGRS based on top GWAS hits (ß = 0.49, 95% CI:0.38-0.60, p < 0.001). Variations in nuclear DNA are potentially associated with maternal mtDNA copy number.

The genomics of prematurity in an era of more precise clinical phenotyping: A review.

Spontaneous preterm birth is a major public health problem, with a clear genetic component. Genetic association studies have evolved substantially in recent years, moving away from the traditional candidate gene analyses to newer approaches utilizing sophisticated analysis platforms to examine sequencing data, and shifting towards functional studies including methylation analysis. It is becoming increasingly evident that careful clinical phenotyping is crucial to high quality genetic association studies regardless of the assay or platform being used. Nonetheless, genetic studies of prematurity are hampered by numerous challenges including small sample sizes, incomplete phenotying, population stratification, and multiple comparisons. As the costs of sequencing and functional analyses continue to decrease, unbiased genome-wide assays will be more widely available. Researchers have met improved success recently when critically applying clinical phenotyping knowledge to group women prior to analyzing genotyping results. Eventually, as the analytic approaches evolve, it is likely that this methodology (combining precisely clinically phenotyped subjects with genome-wide data) will provide key information regarding the pathophysiology of prematurity, and provide potential new avenues for exploring innovative therapeutic strategies.

Association of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism with preterm delivery and placental abruption: a systematic review and meta-analysis.

INTRODUCTION: The aim of this study was to summarize evidence on the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and odds of preterm delivery and placental abruption. MATERIAL AND METHODS: PubMed, EMBASE, CBM (Chinese Biomedical Database) and CNKI (Chinese National Knowledge Infrastructure) were searched to identify eligible studies published in English or Chinese before 12 August 2014. The pooled odds ratios (ORs) with 95% confidence intervals were estimated for the association of MTHFR C677T polymorphism with preterm delivery and placental abruption using random effects models. RESULTS: A total of 22 studies that met inclusion and exclusion criteria were included in this meta-analysis. Regardless of the genetic model tested we found no statistically significant association of MTHFR C677T polymorphism with preterm delivery or placental abruption. Funnel plots inspections, Begg's test and Egger's test did not show evidence of publication bias. CONCLUSIONS: This meta-analysis demonstrated that overall there was no association of MTHFR C677T polymorphism with preterm delivery or placental abruption.

Circadian clock-related genetic risk scores and risk of placental abruption.

INTRODUCTION: The circadian clock plays an important role in several aspects of female reproductive biology. Evidence linking circadian clock-related genes to pregnancy outcomes has been inconsistent. We sought to examine whether variations in single nucleotide polymorphisms (SNPs) of circadian clock genes are associated with PA risk. METHODS: Maternal blood samples were collected from 470 PA case and 473 controls. Genotyping was performed using the Illumina Cardio-MetaboChip platform. We examined 119 SNPs in 13 candidate genes known to control circadian rhythms (e.g., CRY2, ARNTL, and RORA). Univariate and penalized logistic regression models were fit to estimate odds ratios (ORs); and the combined effect of multiple SNPs on PA risk was estimated using a weighted genetic risk score (wGRS). RESULTS: A common SNP in the RORA gene (rs2899663) was associated with a 21% reduced odds of PA (P < 0.05). The odds of PA increased with increasing wGRS (Ptrend < 0.001). The corresponding ORs were 1.00, 1.83, 2.81 and 5.13 across wGRS quartiles. Participants in the highest wGRS quartile had a 5.13-fold (95% confidence interval: 3.21-8.21) higher odds of PA compared to those in the lowest quartile. Although the test for interaction was not significant, the odds of PA was substantially elevated for preeclamptics with the highest wGRS quartile (OR = 14.44, 95%CI: 6.62-31.53) compared to normotensive women in the lowest wGRS quartile. DISCUSSION: Genetic variants in circadian rhythm genes may be associated with PA risk. Larger studies are needed to corroborate these findings and to further elucidate the pathogenesis of this important obstetrical complication.

Placental mitochondrial DNA content and placental abruption: a pilot study.

BACKGROUND: Mitochondrial biogenesis and adequate energy production are important for embryogenesis and placentation. Previous studies documented alterations in maternal blood mitochondrial DNA (mtDNA) copy number-a marker of mitochondrial dysfunction-in pregnancies complicated by placental abruption. To further understand the role of mitochondrial dysfunction in the pathogenesis of placental abruption, we conducted a pilot study using placental specimen collected from 103 placental abruption cases and 102 non-abruption controls. Real-time quantitative polymerase chain reaction (PCR) was used to assess the relative copy number of mtDNA in DNA extracted from placental samples collected immediately after delivery. Logistic regression procedures were used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Higher odds of placental abruption was observed with increasing mtDNA copy number (p value for trend = 0.05). The odds of placental abruption was elevated among women who delivered placentas with higher mtDNA copy number (≥120.5, the median) as compared with those with lower values (<120.5) (adjusted OR = 2.38; 95% CI 1.11-5.08). CONCLUSION: We found preliminary evidence for associations of target tissue-specific mitochondrial dysfunction with an adverse perinatal outcome, placental abruption. Larger studies and replication of findings in other populations will further our understanding of relationships between cellular and genomic biomarkers of normal and abnormal placental function and vascular placental disorders.

Genetic regulation of recurrent spontaneous abortion in humans.

Recurrent pregnancy loss, defined as a pregnancy failure occurring before 24 weeks of gestation more than two or three times according to most definitions, is a fertility defect encountered in 1-5% of the patients. This defect is of course of multifactorial origin. Among the possible origins of recurrent pregnancy loss are uterine structural defaults, defective ploidy control of the embryo, defective immunological dialog between the embryo (or the fetus) and the uterus sometimes in relation with immunological disorders (such as autoimmune diseases), thrombophilia, and free radical metabolism imbalance. Numerous studies attempted to correlate variants of genes supposed to be intervening in the different facets of the early maternal-fetal or maternal-embryonic dialog, and eventually modify the outcome of fertilization, leading to success or failure of post-implantation development. The objective of the present review is to portray the major genes and gene polymorphisms studied for their putative association with recurrent pregnancy loss. Most of these genes have been studied as candidate genes for which strong biological arguments were put forward as to their putative involvement in recurrent pregnancy loss. They were mostly studied by genetic analysis, often in various populations of different ethnic origins, throughout the world. Some of these studies were available only in English as abstracts and were nevertheless used if the information was given with enough detail. With the space being too short to depict all the available literature, different major pathways relevant to the scientific question are presented without any attempt to hide the fact that discordant views often aroused for a given gene.

Placental genome and maternal-placental genetic interactions: a genome-wide and candidate gene association study of placental abruption.

While available evidence supports the role of genetics in the pathogenesis of placental abruption (PA), PA-related placental genome variations and maternal-placental genetic interactions have not been investigated. Maternal blood and placental samples collected from participants in the Peruvian Abruptio Placentae Epidemiology study were genotyped using Illumina's Cardio-Metabochip platform. We examined 118,782 genome-wide SNPs and 333 SNPs in 32 candidate genes from mitochondrial biogenesis and oxidative phosphorylation pathways in placental DNA from 280 PA cases and 244 controls. We assessed maternal-placental interactions in the candidate gene SNPS and two imprinted regions (IGF2/H19 and C19MC). Univariate and penalized logistic regression models were fit to estimate odds ratios. We examined the combined effect of multiple SNPs on PA risk using weighted genetic risk scores (WGRS) with repeated ten-fold cross-validations. A multinomial model was used to investigate maternal-placental genetic interactions. In placental genome-wide and candidate gene analyses, no SNP was significant after false discovery rate correction. The top genome-wide association study (GWAS) hits were rs544201, rs1484464 (CTNNA2), rs4149570 (TNFRSF1A) and rs13055470 (ZNRF3) (p-values: 1.11e-05 to 3.54e-05). The top 200 SNPs of the GWAS overrepresented genes involved in cell cycle, growth and proliferation. The top candidate gene hits were rs16949118 (COX10) and rs7609948 (THRB) (p-values: 6.00e-03 and 8.19e-03). Participants in the highest quartile of WGRS based on cross-validations using SNPs selected from the GWAS and candidate gene analyses had a 8.40-fold (95% CI: 5.8-12.56) and a 4.46-fold (95% CI: 2.94-6.72) higher odds of PA compared to participants in the lowest quartile. We found maternal-placental genetic interactions on PA risk for two SNPs in PPARG (chr3:12313450 and chr3:12412978) and maternal imprinting effects for multiple SNPs in the C19MC and IGF2/H19 regions. Variations in the placental genome and interactions between maternal-placental genetic variations may contribute to PA risk. Larger studies may help advance our understanding of PA pathogenesis.

Non-mosaic uniparental trisomy 16 presenting with asplenia syndrome and placental abruption: a case report and literature review.

Non-mosaic trisomy 16 is rarely seen in later gestation. Herein, we report a fetus with uniparental complete trisomy 16 manifesting with asplenia syndrome, left hand deformity (only 3 deformed fingers on the left hand) and a left low-set ear. The pregnancy ended in severe placental abruption and resultant fetal demise, and maternal hypovolemic shock at 35 weeks of gestation. Only 3 non-mosaic trisomy 16 fetuses, including this case, have been reported to survive into the second or third trimester. Furthermore, this fetus would be the first case of complete trisomy 16 manifesting as asplenia syndrome.

Abruption-induced preterm delivery is associated with thrombin-mediated functional progesterone withdrawal in decidual cells.

Plasma progesterone levels remain elevated throughout human pregnancy, suggesting that reduced reproductive-tract progesterone receptor (PR) initiates labor. Placental abruption and excess thrombin generation elicit preterm delivery (PTD). PR, glucocorticoid receptor (GR), and total and p-ERK1/2 in decidual cells (DCs) and interstitial trophoblasts (IT) were assessed via immunohistochemical staining in abruption-associated PTD versus gestational-age matched control placentas, and in cultured DCs incubated with estradiol (E2) ± medroxyprogesterone acetate (MPA) ± thrombin. Immunostaining for PR was lower in DC nuclei in abruption versus control decidua and was absent from ITs; GR was higher in IT than DCs, with no abruption-related changes in either cell type; p-ERK1/2 was higher in DCs in abruption than control decidua, with total ERK 1/2 unchanged. Immunoblotting of cultured DCs demonstrated strong E2, weak MPA, and intermediate E2+MPA mediated elevation of PR-A and PR-B levels, with constitutive GR expression. In cultured DCs, thrombin inhibited PR but not GR mRNA levels, reduced PR binding to DNA and [(3)H]progesterone binding to PR, and enhanced phosphorylated but not total ERK1/2 levels. Coincubation with a specific p-ERK1/2 inhibitor reversed thrombin-enhanced p-ERK1/2 and lowered PR levels. Thus, abruption-associated PTD is initiated by functional progesterone withdrawal, as indicated by significantly reduced DC nuclear expression of PR-A and PR-B. Functional withdrawal of progesterone results in increased p-ERK1/2, and is thus one pathway initiating abruption-associated PTD.

[Thrombophilic mutation by women with serious pregnancy complications]. / Výskyt trombofilních mutací zen se závaznými tehotenskými komplikacemi.

OBJECTIVE: The purpose of this study was to determine whether maternal or fetal genotype frequencies of the inherited thrombophilic gene mutation (F V Leiden, F II) are altered in adverse pregnancy outcomes - severe preeclampsia, IUGR, abruption of placenta and stillbirth. DESIGN OF THE STUDY: Retrospective study. SETTING: Department of Gynecology and Obstetrics of the Teaching Hospital and the 2nd Medical Faculty of the Charles University in Prague. METHODS: We studied 232 women who had pregnancy complications. All women were tested postpartum for mutation of factor V Leiden and G20210A prothrombine gene. At the same time were tested the newborns of those women. RESULTS: In the group of women with preeklampsia (n=141) we have demonstrated 5 women with mutation encoding for F V, 5 women with mutation encoding for F II and 1 combination of both. In the group of IUGR 2 women with mutation F V, 1 with mutation F II a 1 combination of both were found. In women after stillbirth occure two mutation of F V, one mutation of F II and one combination of both. In the group with abruptio of placenta was 1 case of mutation F V and 3 cases of mutation F II. When we tested a newborn we found 4 cases of mutation F V and 3 cases of F II in the group with preeclampsia, 4 cases of mutation F V 3 cases od mutation of F II in the group with IUGR, no case in the group with abruptio of placenta and 1 case in a death fetus. There was no assotiation between any severe pregnancy complications and any of the maternal or fetal inherited thrombophilia. CONCLUSION: Factor V Leiden and prothrombin gene mutations did not seem play a significant role in adverse pregnancy outcome in our population.