Associations between 2 polymorphisms in the methylenetetrahydrofolate reductase gene and placental abruption

Placental abruption at near-term and term gestations: pathophysiology, epidemiology, diagnosis, and management

Placental abruption is the premature separation of the placenta from its uterine attachment before the delivery of a fetus. The clinical manifestations of abruption typically include vaginal bleeding and abdominal pain with a wide variety of abnormal fetal heart rate patterns. Clinical challenges arise when pregnant people with this condition present with profound vaginal bleeding, necessitating urgent delivery, especially when there is a concern for maternal and fetal compromise and coagulopathy. Abruption occurs in 0.6% to 1.2% of all pregnancies, with nearly half of abruption occurring at term gestations. An exposition of abruption at near-term (defined as the late preterm period from 34 0/7 to 36 6/7 weeks of gestation) and term (defined as ≥37 weeks of gestation) provides unique insights into its direct effects, as risks associated with preterm birth do not impact outcomes. Here, we explore the pathophysiology, epidemiology, and diagnosis of abruption. We discuss the interaction of chronic processes (decidual and uteroplacental vasculopathy) and acute processes (shearing forces applied to the abdomen) that underlie the pathophysiology. Risk factors for abruption and strengths of association are summarized. Sonographic findings of abruption and fetal heart rate tracings are presented. In addition, we propose a management algorithm for acute abruption that incorporates blood loss, vital signs, and urine output, among other factors. Lastly, we discuss blood component therapy, viscoelastic point-of-care testing, disseminated intravascular coagulopathy, and management of abruption complicated by fetal death. The review seeks to provide comprehensive, clinically focused guidance during a gestational age range when neonatal outcomes can often be favorable if rapid and evidence-based care is optimized.

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.

Methylation map genes can be critical in determining the methylome of intracranial aneurysm patients

Aim: Intracranial aneurysm is often asymptomatic until the time of rupture. Elevated homocysteine is reported in vascular diseases. Identifying early events in homocysteine metabolism through methylation map genes may prevent fatality. Materials & methods: In the present study, we investigated the role of variants in methylation map genes in ethnically matched 480 individuals that can influence the homocysteine levels and promote development of aneurysm. Results: The study demonstrates that the genetic variants in folate cycle and methionine cycle genes such as MTHFR, MTRR, MTR, BHMT and DNMT1 are associated with the risk of aneurysm. Conclusion: The associated allelic variants in these genes have functional relevance and are predictive of decreased expression indicative of altered methylation levels that may result in elevated homocysteine.

Change in paternity, risk of placental abruption and confounding by birth interval: a population-based prospective cohort study in Norway, 1967-2009

OBJECTIVES

We examined abruption risk in relation to change in paternity, and evaluated if birth interval confounds this association.

SETTING

Population-based study of singleton births in Norway between 1967 and 2009.

PARTICIPANTS

Women who had their first two (n=747 566) singleton births in the Norwegian Medical Birth Registry. The associations between partner change between pregnancies and birth interval were examined in relation to abruption in a series of logistic regression models.

PRIMARY OUTCOME MEASURES

Risk, as well as unadjusted and adjusted OR of placental abruption in relation to change in paternity and interval between births.

RESULTS

Among women without abruption in their first pregnancy, the risks of abruption in the second pregnancy were 4.7 and 6.5 per 1000 in women who had the same and different partners, respectively (OR=1.39, 95% CI 1.26 to 1.53). After adjustments for confounders including birth interval and smoking, partner change was not associated with abruption (OR=1.01, 95% CI 0.79 to 1.32). Among women with abruption in the first pregnancy, the association between partner change and abruption in the second pregnancy was 0.98 (95% CI 0.75 to 1.28). Interval <1 year was associated with increased abruption risk in the second pregnancy among women with the same as well as different partners, but interval over 4 years was only associated with increased risk among women with the same partner. No such patterns were seen for recurrent abruption.

CONCLUSIONS

We find no evidence that a change in partner is associated with increased abruption risk. Theories supporting an immune maladaptation hypothesis afforded by change in paternity are not supported insofar as abruption is concerned.

Inherited and acquired thrombophilias

Thrombophilias represent an evolving story that continues to stir controversy for care providers and obstetrical patients. The predominant thrombophilic mutations include the factor V Leiden mutation, prothrombin gene mutation G20210A, methylene tetrahydrafolate reductase C667T, and deficiencies of the natural anticoagulants proteins C and S, and antithrombin. Prospective cohort studies have provided an accurate assessment of the risk of placenta-mediated complications posed by common inherited thrombophilic conditions. Acquired thrombophilic conditions consist of the antiphospholipid antibody syndrome (APAS) and hyperhomocysteinemia. Well-conducted, placebo-controlled, randomized trials have demonstrated no benefit of anticoagulation in women with recurrent pregnancy loss and inherited thrombophilia. The routine use of anticoagulation to prevent other placenta-mediated complications in the setting of inherited thrombophilia should be considered experimental until the results of adequate clinical trials are available. Heparin anticoagulation and antiplatelet therapies are the cornerstone of treatment of APAS in pregnancy.

Methylenetetrahydrofolate Reductase C677T and A1298C Mutations in Women with Recurrent Spontaneous Abortions in the Northwest of Iran

Introduction. Recurrent spontaneous abortion (RSA) is a significant obstetrical complication that may occur during pregnancy. Various studies in recent years have indicated that two common mutations (C677T and A1298C) of the methylenetetrahydrofolate reductase (MTHFR) gene are risk factor for RSA. This study was carried out to determine the influence of (C677T and A1298C) of the methylenetetrahydrofolate reductase (MTHFR) gene mutations with RSA. Materials and Methods. A total of 139 women were included in this study: 89 women with two or more consecutive miscarriages and 50 healthy controls. Total genomic DNA was isolated from blood leukocytes. To determine the frequency of the two common C677T and A1298C MTHFR gene mutations in the patients and controls, we used two methods, amplification refractory mutation system-PCR and PCR-restriction fragment length polymorphism. Results. There is no significant difference in the prevalence of 677T/T genotype among women with RSA and healthy controls (P = 0.285). Also no statistically significant difference in the frequency of A1298C MTHFR gene mutation was detected between the two groups (P = 0.175 ). Conclusion. In conclusion, the results indicate that the Amplification Refractory Mutation System-PCR method was in complete concordance with the results obtained by standard PCR-restriction fragment length polymorphism method. The results also show no significant difference in MTHFR C677T/A1298C genotype distribution among the two groups; therefore, further studies on larger population and other genetic variants to better understand the pathobiology of RSA are needed.

Effects of maternal 5,10-methylenetetrahydrofolate reductase C677T and A1298C Polymorphisms and tobacco smoking on infant birth weight in a Japanese population

Background

Intracellular folate hemostasis depends on the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. Because 5,10-MTHFR 677TT homozygosity and tobacco smoking are associated with low folate status, we tested the hypothesis that smoking in mothers with 5,10-MTHFR C677T or A1298C polymorphisms would be independently associated with lower birth weight among their offspring.

Methods

We assessed 1784 native Japanese mother-child pairs drawn from the ongoing birth cohort of The Hokkaido Study on Environment and Children’s Health. Data (demographic information, hospital birth records, and biological specimens) were extracted from recruitments that took place during the period from February 2003 to March 2006. Maternal serum folate were assayed by chemiluminescent immunoassay, and genotyping of 5,10-MTHFR C677T/A1298C polymorphisms was done using a TaqMan allelic discrimination assay.

Results

The prevalence of folate deficiency (<6.8 nmol/L) was 0.3%. The 5,10-MTHFR 677CT genotype was independently associated with an increase of 36.40 g (95% CI: 2.60 to 70.30, P = 0.035) in mean infant birth weight and an increase of 90.70 g (95% CI: 6.00 to 175.50, P = 0.036) among male infants of nonsmokers. Female infants of 677TT homozygous passive smokers were 99.00 g (95% CI: −190.26 to −7.56, P = 0.034) lighter. The birth weight of the offspring of smokers with 5,10-MTHFR 1298AA homozygosity was lower by 107.00 g (95% CI: −180.00 to −33.90, P = 0.004).

Conclusions

The results suggest that, in this population, maternal 5,10-MTHFR C677T polymorphism, but not the 5,10-MTHFR A1298C variant, is independently associated with improvement in infant birth weight, especially among nonsmokers. However, 5,10-MTHFR 1298AA might be associated with folate impairment and could interact with tobacco smoke to further decrease birth weight.

Rare case of spina bifida in both twins with possible genetic basis

Neural tube defects (NTD) are a group of congenital malformations of the brain and spine, the etiology of which is still debated. Although presumed to be the consequence of interactions between genetic and environmental factors, so far, it is not known which genes are involved in the pathogenesis of these malformations. NTD affecting both fetuses in a twin gestation is a rare event. In view of this rarity, we present a case of dichorionic diamniotic twin pregnancy with spina bifida in both fetuses concordantly. This gestation was preceeded by another dichorionic diamniotic twin pregnancy that was complicated by placental abruption.

Novel insights into molecular mechanisms of abruption-induced preterm birth

Preterm birth (PTB) complicates more than 12% of all deliveries. Despite significant research, the aetiology of most cases of PTB remains elusive. Two major antecedents of PTB, intra-amniotic infection and decidual haemorrhage (abruption), can exhibit dissimilar demographic and genetic predispositions, despite sharing common molecular and cellular pathways. The use of high-throughput, high-dimensional technologies reveals substantial crosstalk between the coagulation and inflammation pathways. Tissue factor, thrombin and cytokines are key mediators of this crosstalk. Abruptions are associated with excess thrombin generated from decidual-cell-expressed tissue factor. Although thrombin is a primary mediator of the coagulation cascade, it can also promote inflammation-associated PTB by enhancing expression of matrix metalloproteinase and neutrophil-chemoattracting and -activating chemokines. Here, we provide novel insights into the molecular mechanisms and pathways leading to PTB in the setting of placental abruption.

The Normal anticoagulant system and risk of placental abruption: protein C, protein S and resistance to activated protein C

OBJECTIVE

To examine the association between maternal thrombophilia associated with anticoagulation (proteins C and S and activated protein C resistance ratio, APCR) and risk of placental abruption.

METHODS

Data were derived from a case-control study - The New Jersey-Placental Abruption Study (2002-2007). Maternal blood was collected from abruption cases and controls and was assayed for the thrombophilias. Decreased protein C, S and APCR was defined as values <5% and <10% among controls.

RESULTS

Of a total of 132 cases and 127 controls, 3 were heterozygous for the factor V Leiden mutation (1 case and 2 controls). Mean (± standard deviation) protein C (114.2 ± 25.6 vs. 121.4 ± 27.6; P=0.009), protein S (39.9 ± 18.4 vs. 35.7 ± 15.2; P=0.043) and APCR (2.86 ± 0.29 vs. 2.88 ± 0.27; P=0.039) were different between cases and controls. Abruption cases were associated with an odds ratio of 3.2 (95% CI 1.2, 9.9) in relation to decreased protein C (<Fifth centile). Decreases in both protein S and APCR ratio were not associated with abruption.

CONCLUSIONS

A decrease in protein C was associated with an increased risk for abruption, suggesting an important role for the physiologic anticoagulant system in the etiology of placental abruption.

Thromboembolic diseases in families of women with placental abruption

BACKGROUND

We explored the incidence of thromboembolic disease in relatives of women diagnosed with placental abruption, a condition that may be related to disordered coagulation.

METHODS

Using data from a multicenter, case-control study of placental abruption, we assessed thromboembolic diseases in first-degree male and female relatives of women with and without abruption. The analysis was restricted to biologic parents and full siblings, below 65 years of age, and corrected for familial clustering.

RESULTS

The prevalence of thromboembolic disease was 7.5% in 852 relatives of 212 placental abruption cases and 4.8% in 792 relatives of 206 controls. This increased risk was driven by an association among sisters of abruption probands (odds ratio = 6.8 [95% confidence interval = 1.8-26.0]), and to a lesser extent, among mothers (2.0 [1.0-4.2]). The risk of thromboembolic diseases was similar among the male relatives of placental abruption cases and controls.

CONCLUSIONS

These data suggest that thromboembolic diseases aggregate within female relatives of women with placental abruption.

Diagnosis of placental abruption: relationship between clinical and histopathological findings

OBJECTIVE

We evaluated the extent to which histologic lesions bearing a diagnosis of abruption conform to a diagnosis based on established clinical criteria. We further examined the profile of chronic and acute histologic lesions associated with clinical abruption.

METHODS

Data from the New Jersey-Placental Abruption Study - a multi-center, case-control study - were utilized to compare the clinical and histologic criteria for abruption. The study was based on 162 women with clinically diagnosed abruption and 173 controls. We examined the concordance between clinical indicators for abruption with those of a histopathological diagnosis. The clinical criteria for a diagnosis of abruption included (i) evidence of retroplacental clot(s); (ii) abruption diagnosed on prenatal ultrasound; or (iii) vaginal bleeding accompanied by nonreassuring fetal status or uterine hypertonicity. The pathological criteria for abruption diagnosis included hematoma, fibrin deposition, compressed villi, and hemosiderin-laden histiocytes in cases with older hematomas. Acute lesions included chorioamnionitis, funisitis, acute deciduitis, meconium stained membranes, villous stromal hemorrhage, and villous edema. Chronic lesions included chronic deciduitis, decidual necrosis, decidual vasculopathy, placental infarctions, villous mal-development (delayed or accelerated maturation), hemosiderin deposition, intervillous thrombus, and chronic villitis.

RESULTS

Of clinically diagnosed cases, the sensitivity and specificity for a histologic confirmation of abruption were 30.2% and 100%, respectively. Presence of retroplacental clots remained the single most common finding (77.1%) among clinically diagnosed cases. Among the acute lesions, chorioamnionitis and funisitis were associated with abruption. The only chronic histologic lesion associated with abruption was placental infarctions.

CONCLUSIONS

The concordance between clinical and pathologic criteria for abruption diagnosis is poor. The criteria for diagnosing a clinical abruption should include sonographic visualization of abruption, evidence of retroplacental clots, or vaginal bleeding accompanied by nonreassuring fetal status or uterine hypertonicity.

Polymorphisms in thrombophilia and renin-angiotensin system pathways, preterm delivery, and evidence of placental hemorrhage

OBJECTIVE

The purpose of this study was to analyze functional polymorphisms in candidate genes (methylenetetrahydrofolate reductase [MTHFR]677C>T, MTHFR1298A>C, factor 5 1691G>A [FVL], and angiotensinogen (AGT)-6G>A) in relation to a hypothesized placental hemorrhage pathway to preterm delivery (PTD).

STUDY DESIGN

We assessed maternal genotypes, pregnancy outcomes, and placental pathologic evidence among 560 white and 399 black women who were recruited at mid trimester into a prospective cohort study (1998-2004). Odds of dominant genotypes were calculated for PTDs with (n = 56) or without (n = 177) evidence of placental hemorrhage (referent = term) with the use of race-stratified polytomous logistic regression models.

RESULTS

Among white women, FVL GA/AA and AGT(-6) GA/AA were both associated with hemorrhage-related PTDs (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.6-14.2 and OR, 3.8; 95% CI, 1.3-10.5, respectively), but not other PTDs (ORs, 1.2 and 0.9, respectively). FVL GA/AA was associated with placental abruption (OR, 5.8; 95% CI, 1.1-30) among white women. All results were null for MTHFR genotypes.

CONCLUSION

FVL and AGT variant genotypes were associated specifically with hemorrhage-related PTDs.

Abruptio placentae and disseminated intravascular coagulopathy

Abruptio placentae is an important cause of vaginal bleeding in the latter half of pregnancy. The key factor in the pathophysiology is hemorrhage at the decidual-placental interface. Small episodes may escape clinical detection, but severe grades impact significantly on fetal and maternal morbidity and mortality, with the most frequent complications being fetal death, severe maternal shock, disseminated intravascular coagulopathy, and renal failure. Important risk factors for the development of abruptio placentae are previous abruption, hypertensive diseases, abdominal trauma, growth restriction, and smoking. The diagnosis is essentially made on the clinical picture that includes vaginal bleeding (usually dark blood), abdominal pain, and uterine contractions. The essence of management is restoration of circulating volume followed by delivery of the fetus and placenta, most often by cesarean section when the diagnosis is clear and the fetus alive and viable. Aggressive resuscitation and expeditious vaginal delivery are the goals when the fetus is dead.

Occurrence of placental abruption in relatives

OBJECTIVE

The aim of this study was to assess the recurrence of placental abruption by severity, comparing the risk in a woman with that of recurrence in her sister and in the partner of her brother.

DESIGN

Prospective observational study.

SETTING

General population.

POPULATION

Population-based study based on records of pregnancies from the Medical Birth Registry of Norway; 377.902 sisters with 767 395 pregnancies, 168,142 families incorporating 2-10 sisters, and 346,385 brothers with 717,604 pregnancies in their partners were identified.

METHODS

Placental abruption with preterm birth, birthweight below 2500 g or perinatal death was defined as severe, other cases as mild. Because of the nested family data structure, multilevel multivariate regression was used.

MAIN OUTCOME MEASURES

Placental abruption (severe and mild).

RESULTS

Adjusted odds ratios of recurrence of mild and severe abruption were 6.5 (1.7%) and 11.5 (3.8%), respectively, compared with risks of 0.2 and 0.3% in the total population. After a severe abruption, odds ratios in her sisters were 1.7-2.1, whereas mild abruption produced no increased recurrence in sisters. The estimated heritability between sisters of severe abruption was 16%. No excess rate of abruption was observed between sisters and brothers' partners, between brothers' partners, or from brothers' partners to sisters. The odds ratios for a third abruption after a second abruption and a second severe abruption were 38.7 (19%) and 50.1 (24%), respectively.

CONCLUSIONS

The recurrence risk of placental abruption in the same woman was higher after severe than mild abruption. Severe abruption was associated with a two-fold risk in sisters. Pregnancies following a second abruption should be considered very high risk.

Genetic risk factors for placental abruption: a HuGE review and meta-analysis

BACKGROUND

Although the precise pathophysiology that leads to placental abruption is unknown, there is evidence supporting a genetic etiology.

METHODS

We searched PubMed and systematically reviewed all case-control studies that investigated the association between genetic variants and placental abruption. Pooled genetic risks were estimated using fixed and random effects odds ratios.

RESULTS

Twenty-two articles, examining a total of 14 gene polymorphisms were identified. Seven polymorphisms (F5 Arg506Gln, F5 Met385Thr, F2 G20210A, MTHFR A1298C, MTHFD1 Arg653Gln, NOS3 Glu298Asp, AGT Met235Thr) show significant association in individual studies. Six of the 7 (all except F5Met385Thr) were studied more than once and we therefore included them in our meta-analyses. A positive association under the dominant model was found for the F5 Arg506Gln and F2 G20210A polymorphisms. The random-effects odds ratio for the F5 Arg506Gln polymorphism was 3.4 (95% confidence interval = 1.4-8.3) and the fixed-effects odds ratio for the F2 G20210A polymorphism was 6.7 (3.2-13).

CONCLUSION

Considering the multifactorial etiology of abruption and the relatively small numbers of studies and participants, this review provides only the first clues of possible genetic causes. Larger case-control studies that include gene-gene and gene-environment interactions may help to elucidate the genetics of placental abruption further.

Reduced folate carrier 80A-->G polymorphism, plasma folate, and risk of placental abruption

Folate deficiency and maternal smoking are strong risk factors for placental abruption. We assessed whether the reduced folate carrier [NM_194255.1: c.80A-->G (i.e., p.His27Arg)] (RFC-1) polymorphism was associated with placental abruption, and evaluated if maternal smoking modified the association between plasma folate and abruption. Data were derived from the New Jersey-Placental Abruption Study--a multicenter, case-control study of placental abruption (2002-2007). Maternal DNA was assayed for the RFC-1 c.80A-->G polymorphism using a PCR-dependent diagnostic test. Maternal folate (nmol/l) was assessed from maternal plasma, collected immediately following delivery. Due to assay limitations, folate levels at > or =60 nmol/l were truncated at 60 nmol/l. Therefore, case-control differences in folate were assessed from censored log-normal regression models following adjustment for potential confounders. Distribution of the mutant allele (G) of the RFC-1 c.80A-->G polymorphism was similar between cases (52.3%; n = 196) and controls (50.5%; n = 191), as was the homozygous mutant (G/G) genotype (OR 1.1, 95% CI 0.6-2.2). In a sub-sample of 136 cases and 140 controls, maternal plasma folate levels (mean +/- standard error) corrected for assay detection limits were similar between placental abruption cases (63.6 +/- 5.1 nmol/l) and controls (58.3 +/- 4.7 nmol/l; P = 0.270), and maternal smoking did not modify this relationship (interaction P = 0.169). We did not detect any association between the RFC-1 c.80A-->G polymorphism and placental abruption, nor was an association between plasma folate and abruption risk evident. These findings may be the consequence of high prevalence of prenatal multivitamin and folate supplementation in this population (over 80%). It is therefore not surprising that folate deficiency may be rare and that the RFC-1 c.80A-->G polymorphism is less biologically significant for placental abruption.