THBD sequence variants potentially related to recurrent pregnancy loss

Bulk RNA-sequencing, single-cell RNA-sequencing analysis, and experimental validation reveal iron metabolism-related genes CISD2 and CYP17A1 are potential diagnostic markers for recurrent pregnancy loss

BACKGROUND

Recurrent pregnancy loss (RPL) is associated with variable causes. Its etiology remains unexplained in about half of the cases, with no effective treatment available. Individuals with RPL have an irregular iron metabolism. In the present study, we identified key genes impacting iron metabolism that could be used for diagnosing and treating RPL.

METHODS

We obtained gene expression profiles from the Gene Expression Omnibus (GEO) database. The Molecular Signatures Database was used to identify 14 gene sets related to iron metabolism, comprising 520 iron metabolism genes. Differential analysis and a weighted gene co-expression network analysis (WGCNA) of gene expression revealed two iron metabolism-related hub genes. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry were used on clinical samples to confirm our results. The receiver operating characteristic (ROC) analysis and immune infiltration analysis were conducted. In addition, we analyzed the distribution of genes and performed CellChat analysis by single-cell RNA sequencing.

RESULTS

The expression of two hub genes, namely, CDGSH iron sulfur domain 2 (CISD2)and Cytochrome P450 family 17 subfamily A member 1 (CYP17A1), were reduced in RPL, as verified by both qPCR and immunohistochemistry. The Gene Ontology (GO) analysis revealed the genes predominantly engaged in autophagy and iron metabolism. The area under the curve (AUC) demonstrated better diagnostic performance for RPL using CISD2 and CYP17A1. The single-cell transcriptomic analysis of RPL demonstrated that CISD2 is expressed in the majority of cell subpopulations, whereas CYP17A1 is not. The cell cycle analysis revealed highly active natural killer (NK) cells that displayed the highest communications with other cells, including the strongest interaction with macrophages through the migratory inhibitory factor (MIF) pathway.

CONCLUSIONS

Our study suggested that CISD2 and CYP17A1 genes are involved in abnormal iron metabolism, thereby contributing to RPL. These genes could be used as potential diagnostic and therapeutic markers for RPL.

Novel nucleotide variations in the thrombomodulin (THBD) gene involved in coagulation pathways can increase the risk of recurrent pregnancy loss (RPL)

Recurrent pregnancy loss (RPL) is a common but complex complication in fertility conditions, affecting about 15-20% of couples. Although several causes have been proposed for RPL, it occurs in about 35-60% of cases without a known explanation. A strong assumption is that genetic factors play a role in the etiology and pathophysiology of PRL. Therefore, several genes are proposed as candidates in the pathogenesis of RPL. The current study aimed to investigate the effects of nucleotide changes in the THBD (thrombomodulin) gene as an RPL-related candidate gene. This gene encodes a cell receptor for thrombin and is involved in reproductive loss in RPL cases. Its involvement in the natural anticoagulant system has been extensively studied. By genetic screening of the entire coding and noncoding regions of the THBD gene, we found twenty-seven heterozygous and homozygous nucleotide changes. Ten of them led to amino acid substitutions, seven variants were identified in the promoter region, and eight of them occurred in 3'UTR. Potentially, the pathogenicity effects of these variations on THBD protein were evaluated by several prediction tools. The numerous genomic variations prompted noticeable modifications of the protein's structural and functional properties. Furthermore, in-silico scores were consistent with deleterious effects for these mutations. The results of this study provide genetic information that will be useful in the future for clinicians, scientists, and students to understand the unknown causes of RPL better. It may also pave the way for developing diagnostic/prognostic approaches to help treat PRL patients.

Changes of new coagulation markers in healthy pregnant women and establishment of reference intervals in Changsha

OBJECTIVES

There is a high coagulation state in pregnant women, which is prone to coagulation and fibrinolysis system dysfunction. This study aims to explore the latest coagulation markers-thrombomodulin (TM), thrombin-antithrombin complex (TAT), plasmin-α2 plasmin inhibitor complex (PIC), and tissue plasminogen activator/plasminogen activator inhibitor compound (tPAI-C) in different stages of pregnancy, establish reference intervals (RIs) for healthy pregnant women of Chinese population, and to provide an effective and reliable reference for clinicians.

METHODS

A total of 492 healthy pregnant women, who underwent pregnancy examination and delivery in the Department of Obstetrics, Second Xiangya Hospital of Central South University from October 2019 to October 2020, were enrolled for this study. They were assigned into the first trimester group, the second trimester group, the third trimester group, and the puerperium group according to the pregnancy period, and 123 healthy non-pregnant women were selected as the controls. Plasma levels of TM, TAT, PIC and tPAI-C were analyzed by automatic chemiluminescence immunoassay analyzer. The RIs for TM, TAT, PIC, and tPAI-C were defined using non-parametric 95% intervals, determined following Clinical and Laboratory Standards Institute Document C28-A3c (CLSI C28-A3c), and Formulation of Reference Intervals for the Clinical Laboratory Test Items (WS/T402-2012).

RESULTS

TM and TAT levels increased gradually in the first, second, and third trimester women and decreased in the puerperium women (P<0.05 or P<0.01). PIC level of healthy non-pregnant women was lower than that of pregnant women (P<0.05 or P<0.01), but PIC level of pregnant and puerperium women did not differ significantly (P>0.05). tPAI-C level in healthy non-pregnant women was lower than that of pregnant women (P<0.05 or P<0.01), and tPAI-C level was significantly decreases in the puerperium women (P<0.01). The RIs for TM were as follows: Healthy non-pregnant women at 3.20-4.60 TU/mL, the first and second trimester at 3.12-7.90 TU/mL, the third trimester at 3.42-8.29 TU/mL, puerperium at 2.70-6.40 TU/mL. The RIs for TAT were as follows: Healthy non-pregnant women at 0.50-1.64 ng/mL, the first and second trimester at 0.52-6.91 ng/mL, the third trimester at 0.96-12.92 ng/mL, puerperium at 0.82-3.75 ng/mL. The RIs for PIC were as follows: Healthy non-pregnant women at 0.160-0.519 ng/mL, pregnant women at 0.162-0.770 μg/mL. The RIs for tPAI-C were as follows: Healthy non-pregnant women at 1.90-4.80 ng/mL, the first and second trimester at 2.03-9.33 ng/mL, the third trimester at 2.80-14.20 ng/mL, puerperium at 1.10-8.40 ng/mL.

CONCLUSIONS

The levels of 4 new coagulation markers TM, TAT, PIC, and tPAI-C in pregnant women are increased significantly during pregnancy and gradually return to normal after delivery. The RIs for TM, TAT, PIC, and tPAI-C in pregnant women by trimester are established according to CLSI C28-A3c, thus providing a clinical reference for clinician in judgement of thrombotic risk.

Exome-Sequencing Identifies Novel Genes Associated with Recurrent Pregnancy Loss in a Chinese Cohort

Recurrent pregnancy loss (RPL) is a common reproductive problem affecting around 5% of couples worldwide. At present, about half of RPL cases remained unexplained. Previous studies have suggested an important role for genetic determinants in the etiology of RPL. Here, we performed whole-exome sequencing (WES) analysis on 100 unrelated Han Chinese women with a history of two or more spontaneous abortions. We identified 6736 rare deleterious nonsynonymous variants across all patients. To focus on possible candidate genes, we generated a list of 95 highly relevant genes that were functionally associated with miscarriage according to human and mouse model studies, and found 35 heterozygous variants of 28 RPL-associated genes in 32 patients. Four genes (FOXA2, FGA, F13A1, and KHDC3L) were identified as being strong candidates. The FOXA2 nonsense variant was for the first time reported here in women with RPL. FOXA2 knockdown in HEK-293T cells significantly diminished the mRNA and protein expression levels of LIF, a pivotal factor for maternal receptivity and blastocyst implantation. The other genes, with 29 variants, were involved in angiogenesis, the immune response and inflammation, cell growth and proliferation, which are functionally important processes for implantation and pregnancy. Our study identified several potential causal genetic variants in women with RPL by WES, highlighting the important role of genes controlling coagulation, confirming the pathogenic role of KHDC3L and identifying FOXA2 as a newly identified causal gene in women with RPL.

A Systematic Review to Guide Future Efforts in the Determination of Genetic Causes of Pregnancy Loss

Background: Pregnancy loss is the most common obstetric complication occurring in almost 30% of conceptions overall and in 12–14% of clinically recognized pregnancies. Pregnancy loss has strong genetic underpinnings, and despite this consensus, our understanding of its genetic causes remains limited. We conducted a systematic review of genetic factors in pregnancy loss to identify strategies to guide future research.

Methods: To synthesize data from population-based association studies on genetics of pregnancy loss, we searched PubMed for relevant articles published between 01/01/2000-01/01/2020. We excluded review articles, case studies, studies with limited sample sizes to detect associations (N &lt; 4), descriptive studies, commentaries, and studies with non-genetic etiologies. Studies were classified based on developmental periods in gestation to synthesize data across various developmental epochs.

Results: Our search yielded 580 potential titles with 107 (18%) eligible after title/abstract review. Of these, 54 (50%) were selected for systematic review after full-text review. These studies examined either early pregnancy loss (n = 9 [17%]), pregnancy loss &gt;20 weeks' gestation (n = 10 [18%]), recurrent pregnancy loss (n = 32 [59%]), unclassified pregnancy loss (n = 3 [4%]) as their primary outcomes. Multiple genetic pathways that are essential for embryonic/fetal survival as well as human development were identified.

Conclusion: Several genetic pathways may play a role in pregnancy loss across developmental periods in gestation. Systematic evaluation of pregnancy loss across developmental epochs, utilizing whole genome sequencing in families may further elucidate causal genetic mechanisms and identify other pathways critical for embryonic/fetal survival.

Genetic Variants Contributing to Early Recurrent Pregnancy Loss Etiology Identified by Sequencing Approaches

Recurrent pregnancy loss (RPL) affects up to 5% of couples. It is believed that genetic factors contribute to the disease's etiology and pathophysiology. Hundreds of genes represent coherent RPL candidates due to mammalian implantation's inherent complexity. Sanger sequencing (direct sequencing) of candidate genes has identified potential RPL causative genes (and variants), including those regulating embryo implantation and pregnancy maintenance. Although this approach is a reliable technique, the simultaneous analysis of large genomic regions is challenging. Next-generation sequencing (NGS) technology has thus emerged as a useful alternative for determining genetic variants and transcriptomic disturbances contributing to monogenic and polygenic diseases pathogenesis. However, interpreting results remains challenging as NGS experiments provide an enormous amount of complex data. The molecular aspects of specific diseases must be fully understood for accurate interpretation of NGS data. This review was thus aimed at describing (for the first time) the most relevant studies involving Sanger and NGS sequencing, leading to the description of variants related to RPL pathogenesis. Successful RPL-related NGS initiatives (including RNAseq-based studies) and future challenges are discussed. We consider that the information given here should be useful for clinicians, scientists, and students to enable a better understanding of RPL etiology. It may also provide a basis for the development of diagnostic/prognostic approaches contributing toward translational medicine.

Association between the rs2288947 polymorphism of the lncRNA TINCR gene and the risk of recurrent miscarriage in a Southern Chinese population

Studies have shown that many genes that regulate cell migration are associated with susceptibility to recurrent miscarriage. Terminal differentiation-induced non-coding RNA (TINCR) regulates the migration and invasion of a variety of tumor cells and is associated with susceptibility to various diseases. However, whether the lncRNA TINCR polymorphism is associated with susceptibility to recurrent miscarriage is unclear. Therefore, we investigated the relationship between the rs2288947 A > G polymorphism of the lncRNA TINCR and susceptibility to recurrent abortion. We recruited 248 recurrent spontaneous abortion patients and 392 healthy control subjects from the Southern Chinese population and used the TaqMan method for genotyping. There was no evidence that this polymorphism is associated with recurrent miscarriage (AG vs AA: adjusted OR = 0.904, 95% CI = 0.647-1.264, P = 0.5552; GG and AA: adjusted OR = 0.871, 95% CI = 0.475-1.597, P = 0.6542; dominant model: AG/GG vs AA: adjusted OR = 0.898, 95% CI = 0.653-1.236, P = 0.5101; and recessive model: GG vs AA/AG: adjusted OR = 0.910, 95% CI = 0.505-1.639, P = 0.7527). The stratified analysis also showed no significant associations. This study suggests that the rs2288947 A > G polymorphism of the lncRNA TINCR may not be associated with recurrent miscarriage in a Southern Chinese population. A larger multicenter study is needed to confirm our conclusions.

Genetic Variants Contributing to Early Recurrent Pregnancy Loss Etiology Identified by Sequencing Approaches

Recurrent pregnancy loss (RPL) affects up to 5% of couples. It is believed that genetic factors contribute to the disease's etiology and pathophysiology. Hundreds of genes represent coherent RPL candidates due to mammalian implantation's inherent complexity. Sanger sequencing (direct sequencing) of candidate genes has identified potential RPL causative genes (and variants), including those regulating embryo implantation and pregnancy maintenance. Although this approach is a reliable technique, the simultaneous analysis of large genomic regions is challenging. Next-generation sequencing (NGS) technology has thus emerged as a useful alternative for determining genetic variants and transcriptomic disturbances contributing to monogenic and polygenic diseases pathogenesis. However, interpreting results remains challenging as NGS experiments provide an enormous amount of complex data. The molecular aspects of specific diseases must be fully understood for accurate interpretation of NGS data. This review was thus aimed at describing (for the first time) the most relevant studies involving Sanger and NGS sequencing, leading to the description of variants related to RPL pathogenesis. Successful RPL-related NGS initiatives (including RNAseq-based studies) and future challenges are discussed. We consider that the information given here should be useful for clinicians, scientists, and students to enable a better understanding of RPL etiology. It may also provide a basis for the development of diagnostic/prognostic approaches contributing toward translational medicine.