An Overview of Genetic and Molecular Factors Responsible for Recurrent Pregnancy Loss

Unravelling the oxygen factor - An investigation of transcriptional activation of hypoxia associated placental angiogenesis in recurrent pregnancy loss (RPL) patients from Assam, India

INTRODUCTION

Recurrent pregnancy loss (RPL) is defined as the spontaneous loss of two or more consecutive pregnancies before 20 weeks of gestation, and affects 7.46 % of the Indian population. About 40-50 % of RPL cases are idiopathic making it a therapeutic challenge for clinicians. This study focuses on elucidating the role of hypoxia-associated placental angiogenesis in these idiopathic RPL cases.

METHODS

Whole blood and product of conception (POCs) were collected from RPL patients (N = 87) and cases of voluntary abortions (medically terminated pregnancy, MTP; n = 110) as controls with informed consent. Serum separated from whole blood was used to study the ROS-antioxidant status in the cases and controls through colorimetric assays and ELISA. The mRNA extracted from placental tissue samples were used to determine the hypoxic and angiogenic status in cases and controls through real time PCR. Statistical analysis was also carried out to correlate the differential hypoxic status between RPL and MTP cohorts with the expression of angiogenic factors (VEGFA, VEGFR1 and VEGFR2).

RESULTS

HIF1α mRNA expression was found to be upregulated in the RPL cases. While the serum levels of H2O2 (p = 0.012), guanine oxides and lipid hydroperoxides (LPO) were increased in the RPL cases, reduced glutathione (GSH) was found to be significantly decreased (p = 0.012). Additionally, AUROC analysis also shows an excellent discriminatory ability of 0.850 for serum H2O2 levels. VEGF-A and VEGF-R1 mRNA expression was also found to be downregulated in the RPL cases compared to MTP.

DISCUSSION

This study indicates that increased oxidative stress may lead to aberrations in the VEGF pathway resulting in improper placentation in RPL cases, and subsequently, pregnancy loss.

Aberrations in the progesterone pathway and the Th1/Th2 cytokine dichotomy - An evaluation of RPL predisposition in the northeast Indian population

PROBLEM

Recurrent pregnancy loss (RPL) is the spontaneous loss of two or more consecutive pregnancies prior to 20 weeks of gestation, occurring in 1% of the reproductive-age population. It is a major cause of infertility in India with a staggering 7.46% prevalence rate.

METHOD OF STUDY

Blood and product of conception (POCs) from RPL cases (n = 65) were enrolled for this study, along with cases of medically terminated pregnancy (MTP, n = 80) and term delivery cases (n = 90) as control. ELISA for progesterone and progesterone induced blocking factor (PIBF) levels was carried out, followed by mRNA expression analysis of progesterone receptor isoform B (PR-B) and its downstream immunomodulatory effectors, namely, PIBF, IL-10 and IL-12. Screening of PROGINS haplotype of PR gene and PIBF polymorphism were also conducted to correlate with their respective gene expression profiles.

RESULTS

Serum progesterone level was found to be comparable in the RPL and MTP cases. Although the mRNA expression of PR-B was found to be downregulated in the RPL cases, no significant PROGINS haplotype was observed. Presence of a single nucleotide polymorphism (SNP) in the PIBF gene (rs1372000) was more in healthy controls compared to RPL cases. Serum PIBF levels were found to be lower in the RPL cases with a resultant increase in IL-12 and a decrease in IL-10 mRNA expression in these cases.

CONCLUSIONS

This study indicates that progesterone, acting through PIBF, modulates the immunological state of pregnancy to be Th1-biased in RPL, indicative of a pro-inflammatory, labour-like state not desired for a healthy pregnancy.

The Frequency and Spectrum of Chromosomal Translocations in a Cohort of Sri Lankans

Translocations are the most common type of structural chromosomal abnormalities. Unbalanced translocations are usually found in children who present with congenital abnormalities, developmental delay, or intellectual disability. Balanced translocations are usually found in adults who frequently present with reproductive failure; either subfertility, or recurrent pregnancy loss. Herein, we report the spectrum and frequency of translocations in a Sri Lankan cohort. A database of patients undergoing cytogenetic testing was maintained prospectively from January 2007 to December 2016 and analyzed, retrospectively. A total of 15,864 individuals were tested. Among them, 277 (1.7%) had translocations. There were 142 (51.3%) unbalanced translocations and 135 (48.7%) balanced translocations. Majority (160; 57.8%) were Robertsonian translocations. There were 145 (52.3%) children and adolescents aged less than 18 years with translocations, and 142 (97.9%) were unbalanced translocations. Majority [138 (95.2%)] were referred due to congenital abnormalities, developmental delay, or intellectual disability, and 91 were children with translocation Down syndrome. All adults aged 18 years or above (132) had balanced translocations. Subfertility and recurrent pregnancy loss [84 (63.6%)] and offspring(s) with congenital abnormalities [48 (36.4%)] were the most common indications in this group. Majority (68.2%) in this group were females with reciprocal translocations (55.3%). Chromosomes 21, 14, and 13 were the most commonly involved with rob(14q21q) [72 (26%)], rob(21q21q) [30 (13.7%)], and rob(13q14q) [34 (12.3%)] accounting for 52% of the translocations. Chromosomes 1, 8, 11, and 18 were most commonly involved in reciprocal translocations. The observed high frequency of chromosomal translocations in our cohort highlights the importance of undertaking cytogenetic evaluation and providing appropriate genetic counseling for individuals with the phenotypes associated with these translocations.

A feasible diagnostic approach for the translocation carrier from the indication of products of conception

Background

Chromosome translocations are rare but frequently associated with infertility. The objective of this study is to investigate the feasibility of using chromosomal microarray analysis (CMA) on products of conception (POC) samples as an indicator of parental balanced translocation. From January 2011 to December 2016, CMA using Affymetrix Cytoscan™750K array was performed on 1294 POC samples in our hospital. Karyotyping and fluorescence in situ hybridization (FISH) using parental blood samples were performed to validate the origin of subchromosomal copy number variations (CNVs).

Results

In the 1294 cases of POCs, we detected CNVs of terminal duplication and deletion that imply unbalanced translocation derivatives in 16 cases, and accurate diagnosis with the parental study was made in all the cases by karyotyping and/or FISH. In 10/16 (62.5%) of these cases, CNVs were inherited from one carrier parent of balanced translocation (Cases 1 to 10), while 6/16 (37.5%) cases occurred de novo (Cases 11 to 16).

Conclusion

This study clearly illustrated the importance of the utilization of CMA on POC, followed by parental karyotyping and FISH to better characterize CNVs. This approach is especially useful for couples in whom one partner carries a cryptic/submicroscopic balanced translocation but has an apparently normal karyotype.

Electronic supplementary material

The online version of this article (10.1186/s13039-018-0362-8) contains supplementary material, which is available to authorized users.

Maternal methyltetrahydrofolate reductase gene mutation in patients with missed abortions

Background

Missed abortions are a common problem, often caused by thrombophilia in both recurring and non-recurring cases.

Aim

To determine whether the presence of a mutation in the methyltetrahydrofolate reductase (Mthfr) gene correlates with missed abortions.

Patients and methods

We selected two hundred patients for this study in two groups: the study group, which consisted of one hundred patients with a history of missed abortion; and the control group, which consisted of one hundred patients with no history of missed abortion.

Results

Of the 200 patients, mutations in Mthfr were only found in forty-four patients—thirty-four from the study group and ten from the control group.

Conclusions

Mthfr gene mutation is a common cause of both recurring and non-recurring missed abortions.

Genetics of recurrent miscarriage and fetal loss

Despite years of research, miscarriage, particularly when recurrent, continues to pose a medical challenge. An embryo chromosomal error is responsible for 50-60% of recurrent cases; however, up to 30-50% remains an enigma. Successful pregnancy involves different maternal physiologic changes and certain complex interactions between the fetus and the mother by cytokines, angiogenic mediators and hormones. To date, research lines have focused on genetic and epigenetic polymorphisms related mainly to immune response and inflammatory mediators, and have yielded a significant relationship between recurrent miscarriage and immune mechanisms. Thus, unknown causes of miscarriage could be due to an immune imbalance induced by T-helper Th1/Th2/Th17 cytokines and regulatory T cells. Furthermore, these genes and mediators have long been suspected of being blood markers for the clinical diagnosis and management of miscarriage; however, more evidence is required for them to be included in medical practice and obstetric guidelines.

Interleukin-17 and leptin genes polymorphisms and their levels in relation to recurrent pregnancy loss in Egyptian females

Recurrent pregnancy loss (RPL) is a common problem during early gestation. The aim of our study was to investigate the association of IL-17 F( rs763780), IL-17 A (rs2275913), and leptin (2548 G/A) gene polymorphisms with RPL in obese and lean Egyptian females, and to find out whether these gene polymorphisms affect the women’s serum levels. One hundred and twenty patients with RPL and 120 fertile volunteers with no history of pregnancy loss were genotyped for leptin (2548 G/A), IL-17 A (rs2275913), and IL-17 F (rs763780) polymorphisms by RFLP. The serum level of IL-17 was measured by ELISA, while serum leptin level was measured by HPLC. We found that IL-17 F (rs763780) polymorphism was associated with a decreased risk of RPL in Egyptian females, and we also found that IL-17 A (rs2275913) and LEP (2548 G/A) SNP were associated with an increased risk of RPL. We also demonstrated that both the IL-17 and leptin levels were elevated in the women with RPL and in an obese subgroup within RPL in comparison to a lean one.