Inherited thrombophilia and gestational vascular complications

Maternal carriers of the ANXA5 M2 haplotype are exposed to a greater risk for placenta-mediated pregnancy complications

PURPOSE

Annexin A5 (ANXA5) is a protein abundantly expressed in normal placenta where it contributes to the healthy outcome of a pregnancy. Lower ANXA5 levels have been observed in M2/ANXA5 haplotype carrying chorion. Consequently, this study aimed to assess the potential association of M2 maternal carrier status with the risk of recurrent pregnancy loss (RPL), the timing of miscarriages, and other obstetric complications, for the first time in a population from Latin America.

METHODS

This study was designed as a prospective recruitment of RPL patients with post hoc analysis. The distribution of the M2/ANXA5 haplotype was compared between a group of 229 Argentine women with RPL and 100 parous controls, and was further analyzed in subgroups of patients stratified according to the timing of miscarriages and in relation to other obstetric complications.

RESULTS

No significant differences were found in the distribution of M2 haplotype among either RPL patients or the subgroups with embryonic, early fetal, or late fetal losses compared to parous controls. Notwithstanding, maternal M2/ANXA5 was found to be independently associated with a higher risk of suffering intrauterine growth restriction (IUGR) and/or preeclampsia (PE). Simultaneously, the presence of inherited and/or acquired thrombophilia also proved to be an independent risk factor for these.

CONCLUSIONS

The association found between the maternal carriage of the M2/ANXA5 haplotype and an elevated risk of IUGR and/or PE supports the hypothesis that carrier status of this haplotype and the consequently reduced placental ANXA5 expression might be responsible, at least partially, for the onset of these gestational vascular complications.

Assessment of M2/ANXA5 haplotype as a risk factor in couples with placenta-mediated pregnancy complications

PURPOSE

The aim of this study was to confirm the associated M2/ANXA5 carrier risk in women with placenta-mediated pregnancy complications (PMPC) and to test their male partners for such association. Further analysis evaluated the influence of maternal vs. paternal M2 alleles on miscarriage.

METHODS

Two hundred eighty-eight couples with preeclampsia (PE), intrauterine growth restriction (IUGR), or premature birth (PB) were recruited (n = 96 of each phenotype). The prevalence of the M2 haplotype was compared to two control cohorts. They included a group of women with a history of normal pregnancy without gestational pathology (Munich controls, n = 94) and a random population sample (PopGen controls, n = 533).

RESULTS

Significant association of M2 haplotype and pregnancy complications was confirmed for women and for couples, where prevalence was elevated from 15.4 to 23.8% (p < 0.001). Post hoc analyses demonstrated an association for IUGR and PB individually. A strong link between previous miscarriages and M2 carrier status was identified which may explain the predisposition to placental pregnancy complication. M2/ANXA5 appears to be a risk factor for adverse pregnancy outcomes related, but not limited to miscarriages, with similar prevalence in women and their male partners.

CONCLUSION

These findings support the proposed physiological function of ANXA5 as an embryonic anticoagulant that appears deficient in contiguous specter of thrombophilia-related pregnancy complications culminating more frequently in miscarriage in a maternal M2 carrier background.

Genetic analysis of the M2/ANXA5 haplotype as recurrent pregnancy loss predisposition in the Malay population

PURPOSE

The aim of this study was to evaluate a new predisposition factor, M2/ANXA5 (RPRGL3), in recurrent pregnancy loss (RPL) patients of Malay origin, since it was previously known that the prevalence of this condition is relatively high among the Malay population of Malaysia, where conventional hereditary thrombophilia factors have been generally ruled out.

METHODS

A total of 232 women who had experienced ≥2 unexplained RPL and 141 available male partners were recruited, with 360 healthy Malay and 166 parous female controls. Prevalence of M2 carriage and RPL odds ratios were calculated in (a) control and patient groups; (b) clinically defined subgroups in categories of pregnancy loss, primary, secondary, and tertiary; and (c) timing of pregnancy loss in early, ≤15th gestation week and "late" fetal losses, and >15th gestation week subgroups.

RESULTS

Both male and female subjects had similar M2/ANXA5 allele frequencies. The carrier rate of M2/ANXA5 for the general Malay population was 42.2 and 34.9% for parous controls. These carrier rates compared to Malay RPL subjects (52% M2 carriers) resulted in elevated odds ratios (95% confidence interval) of 1.53 (1.1 to 2.1) and 1.97 (1.3 to 3.1) accordingly for early fetal losses. Moreover, exceeding copy numbers of M2/ANXA5 alleles seemed to afflict a greater chance of RPL in couples, especially when both partners were M2 carriers.

CONCLUSION

This study confirmed the proposed role of M2/ANXA5 as embryonic, genetically associated thrombophilia predisposition factor for early RPL among ethnic Malay of Malaysia.

Lessons From the EThIGII Trial

This study presents sample size considerations derived from the Efficacy of Thromboprophylaxis as an Intervention during Gravidity (EThIGII) trial (ClinicalTrials.gov: NCT00400387) to address the question of low-molecular-weight heparin (LMWH) treatment in women with recurrent pregnancy loss (RPL) depending on the M2/ANXA5 haplotype. To evaluate the possible influence of such treatment on miscarriage rates of trial participants, a post hoc analysis of ANXA5 promoter genotypes in the light of M2/ANXA5 ( RPRGL3) distribution was performed using logistic models. DNA for genotyping was available from 129 LMWH and 95 control patients, 44 (19.6%) of whom were M2/ANXA5 carriers. Miscarriages occurred in 1 (4.0%) of 25 M2/ANXA5 carriers from the LMWH group compared to 4 (21.1%) of 19 in the control group, resulting in an odds ratio (95% confidence interval) for miscarriage of 0.16 (0.016-1.5) for women treated with LMWH. In noncarriers, miscarriage rates were 6 (5.8%) of 104 versus 7 (9.2%) of 76 for the LMWH and the control groups, respectively, corresponding to an odds ratio for miscarriage of 0.60 (0.19-1.9). The apparent beneficial effects of miscarriage rate reduction in M2/ANXA5 carriers with RPL concur with biological considerations about improvement in reduced ANXA5 function through LMWH treatment in an adequate murine model. The data obtained were instrumental to design proper assessment of the existence and magnitude of this effect.

Effects of anticoagulant therapy on pregnancy outcomes in patients with thrombophilia and previous poor obstetric history

This study investigates the effects of anticoagulant therapy on pregnancy outcomes in 204 patients with thrombophilia and previous poor obstetric outcomes. Patients with poor obstetric history (pre-eclampsia, intrauterine growth retardation, fetal death, placental abruption, recurrent pregnancy loss) and having hereditary thrombophilia were included in this study. Poor obstetric outcomes were observed more frequently in patients who had not taken anticogulant therapy compared with treated group. Live birth rate, gestational age at birth and Apgar scores were significantly higher in the treated group when compared with the untreated group. There were no significant differences in terms of birthweight, mode of delivery and admission rates to the neonatal intensive care unit (NICU). Low-molecular-weight heparin (LMWH) plus acetylsalicylic acid (ASA) had higher gestational age at birth, Apgar scores, live birth rate and a lower abortion rates when compared with controls; in contrast, no significant difference was observed in terms of birthweight, mode of delivery, obstetric complications and admission rates to NICU. There were no significant differences between control group and both LMWH only and ASA only groups in terms of gestational age at birth, Apgar scores, birthweight, mode of delivery, obstetric complications and admission rates to NICU. Only LMWH group had higher live birth rate as compared with control group. The use of only ASA did not seem to affect the perinatal complication rates and outcomes. In conclusion, anticoagulant therapy with both LMWH and ASA seems to provide better obstetric outcomes in pregnant women with thrombophilia and previous poor obstetric outcomes.

M2/ANXA5 haplotype as a predisposition factor in Malay women and couples experiencing recurrent spontaneous abortion: a pilot study

Recurrent spontaneous abortion (RSA) is a prevalent condition among the Malay population of Malaysia, where carriage risk of conventional hereditary thrombophilia factors has been generally ruled out. The contribution of M2/ANXA5, a common haplotype in the annexin A5 gene promoter, was evalauted for RSA in Malay. Seventy-seven women who had experienced two or more unexplained RSA and 41 available male partners were selected for study, with 360 population controls recruited from healthy Malay individuals. Incidence of M2 carriage and odds ratios were calculated between control and patient groups, and clinically defined subgroups and RSA risk was evaluated. M2/ANXA5, found in 42.2% of the general Malay population, was associated with greater risks for women with primary and secondary RSA with early (gestational week 5-15) losses. The risk was somewhat higher in Malay couples when both partners were carriers and a trend of higher prevalence was seen for the male partners patients who had experienced RSA. M2 carriage seems to be a risk factor with unusually high incidence in Malay women and couples with primary and secondary RSA with 'early' spontaneous abortions. The associated male partner risk confirms the proposed role of M2/ANXA5 as a genetic trait impeding embryonic anticoagulation.

Multicentre study of the clinical relevance of screening IVF patients for carrier status of the annexin A5 M2 haplotype

Thrombophilia and impaired placental vasculature are a major cause of adverse pregnancy outcome. In 2007, a new hereditary factor for obstetric complications and recurrent pregnancy loss (RPL) was identified as a sequence variation in the core promoter of the annexin A5 gene, ANXA5, called the M2 haplotype. M2 carriership has been demonstrated in couples with recurrent miscarriage and its origin is embryonic rather than specifically maternal, confirmed by subsequent papers. The M2 haplotype is the first report of a hereditary factor related to pregnancy pathology caused by embryonic-induced anticoagulation. It has been demonstrated that couples with RPL had equal and significantly increased M2 carriership and that maternal and paternal carriership confers equal risk. Given its importance for patients with RPL, and potentially implantation failure, this study assessed the incidence of carrier status for the M2 ANXA5 haplotype in both the male and female of couples attending five CARE IVF centres. In 314 patients (157 couples), 44% of couples (one or both partners), 24% of females, 26% of males and 37% of couples with unexplained infertility were M2 carriers. This high incidence has provoked further urgent studies on specific patient populations and on the value of post embryo-transfer therapy.

Predictive value of thrombopath determination in women with infertility and pregnancy complications

BACKGROUND

A condition of maternal thrombophilia, either inherited or acquired, can compromise the success of implantation and foetal survival.

METHODS

Malfunctions in protein C pathway were evaluated using a novel assay [HemosIL ThromboPath (ThP)] in a case-control study of 172 women with a history of recurrent miscarriage or infertility and 86 age-matched unrelated fertile women.

RESULTS

Thrombophilia was ascertained in 13% of the cases. ThP values were lower in women either with or without thrombophilia compared to controls (both p<0.0001). Abnormal ThP values (below the mean minus 1SD of controls) were found in 62% of cases compared to 12% of controls (p<0.0001). Non-thrombophilic women who achieved spontaneous pregnancy had higher ThP values compared to those who did not (p<0.05). Elevated ThP values were an independent predictor for pregnancy (p<0.01) in women without thrombophilia. A decrease of ThP values was observed during pregnancy progression, which correlated with that of protein S (p<0.05). Miscarriage or major complications occurred in women in whom ThP percent change was approximately 2-fold higher than that observed in women who achieved successful pregnancy (p<0.05).

CONCLUSIONS

ThP might represent an efficient assay for screening women with pregnancy complications and might provide prognostic information during pregnancy progression.

A systematic review of the association between factor V Leiden or prothrombin gene variant and intrauterine growth restriction

OBJECTIVE

The purpose of this study was to conduct a systematic review of the literature of studies that examined the association between factor V Leiden and/or prothrombin gene variant and intrauterine growth restriction.

STUDY DESIGN

This systematic review of studies assesses the association between factor V Leiden and/or prothrombin gene variant and intrauterine growth restriction.

RESULTS

Ten case-control studies fulfilled the selection criteria for inclusion in the meta-analysis. There was a significant association between factor V Leiden and intrauterine growth restriction (odds ratio, 2.7; 95% CI, 1.3-5.5) and prothrombin gene variant and intrauterine growth restriction (odds ratio, 2.5; 95% CI, 1.3-5.0). Five cohort studies were identified in the systematic review; 3 studies were prospective (2 full publications), and 2 studies were retrospective (1 full publication). Combining the 2 full publication prospective studies yields a summary relative risk of 0.99 (95% CI, 0.5-1.9).

CONCLUSION

This meta-analysis of case-control studies suggests that the factor V Leiden and prothrombin gene variant both confer an increased risk of giving birth to an intrauterine growth restricted infant, although this may be driven by small, poor-quality studies that demonstrated extreme associations. Large well-conducted prospective cohort studies are required to determine definitively whether an association between thrombophilia and intrauterine growth restriction is present.