ABSTRACT
INTRODUCTION: Factors contributing to recurrent pregnancy loss (RPL) in more than half of the cases are still unknown. The incidence and societal impact of this condition requires urgent elucidation of the mechanisms behind it, which could aid in significant improvement of clinical management. MATERIALS AND METHODS: Using a highly efficient in-solution digestion method and label-free data-independent LC-MS/MS acquisition with ion mobility, we performed comparative proteomics analysis of the decidua tissues from 19 RPL patients and 10 controls. Differentially abundant proteins (DAPs) were compared and correlated with 3 publicly available transcriptomic datasets and the expression of selected biomarkers was tested by qPCR in decidua and chorionic villi from an extended cohort. RESULTS: From 1952 proteins identified based on ≥2 peptides, the statistically significant difference in abundance (Anova p ≤ 0.05) and fold change ≥1.2 showed 85 proteins. Pathway analysis using Reactome, KEGG and Wiki pathways identified enrichment of "Signaling by ROBO receptors", "RNA degradation" and "Cytoplasmic Ribosomal Proteins". The correlation between protein and gene expression in decidua revealed that the down-regulated ribosomal proteins in our dataset (RPS15, RPS17, RPL27A, RPL35A and RPL18) showed the same regulation trend at the mRNA level, which was later confirmed for transcripts of RPS15 and RPL18 in our cohort. DISCUSSION: Our data suggests that the potential causes of RPL from the maternal side could be associated with impaired RNA processing machinery. Furthermore, the list of DAPs in RPL opens future investigations in terms of screening novel gene variants predisposing to pregnancy failure and developing biomarkers for RPL risk.
ABSTRACT
Background: The fetal monogenic causes of early pregnancy losses (EPLs) are mainly unknown, with only a few articles on the subject published. In our previous study of EPLs using whole-exome sequencing analysis, we confirmed a genetic diagnosis of CPLANE1-related Joubert syndrome (JS) in three EPLs from two couples and identified a relatively common CPLANE1 allele among our population (NM_001384732.1:c.1819delT;c.7817T>A, further after referred as "complex allele"). Pathogenic variants in the CPLANE1 (C5orf42) gene are reported to cause JS type 17, a primary ciliopathy with various system defects. Aims: To examine the hypothesis that the CPLANE1 "complex allele," whether homozygous or compound heterozygous, is a common cause of EPLs in our population. Study Design: Cohort study/case-control study.ontrol study. Methods: In this study, we used polymerase chain reaction-based methods to screen for CPLANE1 "complex allele" presence among 246 euploid EPLs (< 12 gestational weeks) from families in North Macedonia. We also investigated the impact of this allele in 650 women with EPLs versus 646 women with no history of pregnancy loss and at least one livebirth, matched by ethnic origin. Results: We found a high incidence of JS in the total study group of EPLs (2.03%), with a considerably higher incidence among Albanian families (6.25%). Although not statistically significant, women with EPLs had a higher allele frequency of the CPLANE1 "complex allele" (AF = 1.38%) than the controls (AF = 0.85%; p = 0.2). Albanian women had significantly higher frequency of the "complex allele" than the Macedonians (AF = 1.65% and 0.39%, respectively; p = 0.003). Conclusion: To the best of our knowledge, this is the highest reported incidence of fetal monogenic disease that might cause EPLs. Targeted screening for the CPLANE1 "complex allele" would be warranted in Albanian ethnic couples because it would detect one JS in every 16 euploid EPLs. Our findings have a larger impact on the pathogenesis of pregnancy loss and contribute to a better understanding of the pathogenicity of the variants in the CPLANE1 gene.
