Sex chromosome characteristics and recurrent miscarriage

Male Contributory Factors in Recurrent Pregnancy Loss

With 40% of idiopathic cases, recurrent pregnancy loss (RPL) is a problem of great concern for patients and clinicians. In addition to financial burden, it causes a lot of frustration and anxiety in affected couples. The primary objective of this review was to gain knowledge of recent advances in the field of recurrent pregnancy losses and to understand the role of male contributory factors in idiopathic cases. For a long time, researchers and clinicians were seeking an explanation for idiopathic RPL (iRPL) in females only; however, with recent advances in reproductive biology, the role of spermatozoa in early embryonic development has caught the attention of researchers. Clinically, only routine semen parameters and karyotyping are investigated in iRPL male partners, which seem to be insufficient in the present scenario, and thus, more information at the molecular level is required for a comprehensive understanding of iRPL. In concluding remarks, we suggest targeted multi-omics investigations in a large cohort to improve our understanding of the role of male contributory factors in iRPL.

Investigation of the role of X chromosome inactivation and androgen receptor CAG repeat polymorphisms in patients with recurrent pregnancy loss: a prospective case-control study

BACKGROUND

Previous research has revealed that skewed X chromosome inactivation (SXCI) and androgen receptor (AR) CAG polymorphisms are associated with increased risk of recurrent pregnancy loss (RPL); however, the results are conflicting, and the underlying mechanisms remain unclear. This study investigated the role of SXCI and AR CAG polymorphisms in patients with RPL and explored whether the underlying mechanisms were related to the ovarian reserve and preimplantation embryo aneuploidy.

METHODS

This was a prospective case-control study carried out in a tertiary hospital-based reproductive medicine center. An external validation RPL cohort was recruited during the study period. Data on baseline and cycle characteristics were collected. X-chromosome inactivation (XCI) was measured using a human AR assay. AR polymorphisms were assessed using quantitative fluorescent polymerase chain reactions and direct sequencing. Blastocysts of the patients with RPL were tested by single nucleotide polymorphism microarray based preimplantation genetic testing for aneuploidy.

RESULTS

In total, 131 patients with idiopathic RPL and 126 controls were included for the case-control study. Patients with RPL exhibited a significantly more skewed XCI distribution pattern (67.71 ± 10.50 vs. 64.22 ± 10.62, p = 0.011), as well as significantly shorter bi-allelic mean (18.56 ± 1.97 vs. 19.34 ± 2.38, p = 0.005) and X-weighted bi-allelic mean (18.46 ± 2.02 vs. 19.38 ± 2.53, p = 0.001) of AR CAG repeats. Multivariate logistic regression models indicated that CAG repeat < 20, SXCI, and duration of stimulation were independently associated with the risk of RPL. However, SXCI and AR CAG polymorphisms were not associated with ovarian reserve or preimplantation embryo aneuploidy in the RPL group, and the same results were attained in a separate validation cohort of 363 patients with RPL.

CONCLUSION

SXCI and AR CAG polymorphisms are related to RPL; however, these two factors do not lead to RPL by affecting the ovarian reserve or increasing embryo aneuploidy. The roles of SXCI and AR CAG in RPL may involve other mechanisms that require further investigation.

TRIAL REGISTRATION

NCT02504281, https://www.

CLINICALTRIALS

gov (Date of registration, 21/07/2015; date of enrolment of the first subject, 30/07/2015).

Loss of X Chromosome Inactivation in Androgenetic Complete Hydatidiform Moles With 46, XX Karyotype

Most complete hydatidiform moles (CHMs) showcase an androgenetic nature of the nuclear genome. In the normal female embryo, one of the 2 X chromosomes is inactive. However, the status of X chromosome inactivation (XCI) in androgenetic CHMs remains unknown. Seventy-one androgenetic CHM tissues with the 46, XX karyotype were collected. Seventy-four normal female villi and 74 normal male villi were collected as controls. The expression of XCI markers (XIST, TSIX, and XACT) and an X-linked gene (CDX4) was detected by real-time polymerase chain reaction. Other XCI-associated genes were also examined, including the methylation status of the human androgen receptor gene (HUMARA) by methylation-specific polymerase chain reaction), and the expression of H3K27me3, USP21, and Nanog by Western blot and immunofluorescence, respectively. In addition, 126 CHMs and 63 normal female villous samples were collected for CDX4 immunohistochemical staining. The expression of XIST RNA was significantly lower, and TSIX RNA expression was significantly higher in androgenetic CHMs than that in normal female villi (both P<0.01). The expression of CDX4 mRNA in androgenetic CHMs was elevated compared with that in normal male and normal female villous samples (both P<0.01), and CDX4 protein expression was also higher than that in normal female villous samples (P<0.01). The expression of H3K27me3 was lower in androgenetic CHMs compared with that in normal female villi(P<0.01). The methylation pattern of HUMARA was found lacking in androgenetic CHMs. The expression of Nanog and UPS21 protein in androgenetic CHMs was higher than that in normal villi (both P<0.01). Both X chromosomes are active in androgenetic CHMs with the 46, XX karyotype, and the USP21-Nanog pathway may be involved in the disruption of XCI during this process.

Male sperm quality and risk of recurrent spontaneous abortion in Chinese couples: A systematic review and meta-analysis

OBJECTIVE

To assess the association of conventional semen parameters and sperm DNA fragmentation with risk of recurrent spontaneous abortion (RSA).

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENTS

Total 1,690 male partners of women with RSA, and 1,337 male partners of fertile control women.

INTERVENTIONS

Case-control or cohort studies were determined by searching PubMed, Google Scholar, Cochrane Libraries, China Biology Medicine disc, Chinese Scientific Journals Fulltext Database, China National Knowledge Infrastructure, and Wanfang Database. RSA was defined as two or more previous pregnancy losses. The fertile women refer to the reproductive women who have had at least a normal pregnancy history and no history of abortion.

MAIN OUTCOME MEASURES

This study included eight outcome measures: semen volume(ml), semen pH value, sperm density(106/ml), sperm viability (%), sperm progressive motility rate (%), normal sperm morphology rate (%), sperm deformity rate(%), sperm DNA fragmentation index (DFI) (%). The summary measures were reported as standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

Finally, twenty-four studies were included for analysis. Overall, male partners of women with RSA had a significantly lower level of sperm density (SMD = -0.53, 95%CI: - 0.75 to -0.30), sperm viability (SMD = -1.03, 95%CI: - 1.52 to -0.54), sperm progressive motility rate (SMD = -0.76, 95%CI:-1.06 - -0.46), and normal sperm morphology rate (SMD =  -0.56, 95%CI: - 0.99 to -0.12), and had a significantly higher rate of sperm deformity rate (SMD = 1.29, 95%CI: 0.60 - 1.97), and sperm DFI (SMD = 1.60, 95%CI: 1.04 to 2.17), when compared with the reference group. However, there were no statistically significant differences for semen volume (SMD = -0.03, 95%CI: -0.14 - 0.08) and semen pH value (SMD =  -0.23, 95% CI: -0.50 to 0.05) among 2 groups.

CONCLUSIONS

The results of this analysis support an association of sperm density, sperm viability, sperm progressive motility rate, normal sperm morphology rate, sperm deformity rate, as well as sperm DFI with RSA. However, given the significant heterogeneity between studies and the lack of more detailed data on the subjects, further large-scale prospective studies are needed.

Role of male genetic factors in recurrent pregnancy loss in Northeast China

OBJECTIVE

This study aimed to investigate the roles of male genetic factors, including Y chromosome microdeletions and chromosomal heteromorphism, in recurrent pregnancy loss (RPL) in Northeast China.

STUDY DESIGN

We evaluated 1072 male patients from Northeast China whose wives had a history of two or more consecutive miscarriages. We also selected 971 infertile and 200 fertile men as control groups. Semen analysis was carried out by computer-assisted sperm analysis. Y chromosome microdeletions were detected by polymerase chain reaction and chromosomes were evaluated by karyotype analysis.

RESULTS

There were no microdeletions in the RPL and fertile control groups, but 112 of the infertile men had Y chromosome microdeletions. Chromosomal heteromorphism was detected in all the groups. Patients in the infertile control group had a significantly higher percentage (2.16%) of Y variation (Yqh±) heteromorphism compared with the RPL group, but there were no significant differences in the incidences of chromosomal heteromorphism among the other groups.

CONCLUSION

Y chromosome microdeletions and chromosomal heteromorphism are not associated with RPL in Northeast China. Some RPL males had structural chromosome anomalies, all of which were reciprocal translocations. We suggest that it may not be necessary to detect Y chromosome microdeletions in RPL males with Yqh±.

Y chromosome azoospermia factor region microdeletions are not associated with idiopathic recurrent spontaneous abortion in a Slovenian population: association study and literature review

OBJECTIVE

To investigate the potential association of Y chromosome microdeletions with idiopathic recurrent spontaneous abortion (IRSA) in a Slovenian population and compare our results with those of previously published studies in different populations, with the intention of clarifying the potential impact of Y chromosome microdeletions on IRSA.

DESIGN

Case-control and association study.

SETTING

Departments of gynecology and obstetrics and university-based research laboratory.

PATIENT(S)

Male partners of 148 couples with at least three spontaneous pregnancy losses of unknown etiology, and 148 fertile men.

INTERVENTION(S)

Multiplex polymerase chain reactions.

MAIN OUTCOME MEASURE(S)

Azoospermia factor (AZF) regions were tested for Y chromosome microdeletions according to European Academy of Andrology/European Molecular Genetics Quality Network guidelines. The PubMed database was searched to retrieve articles linking Y chromosome microdeletions and susceptibility to IRSA.

RESULT(S)

None of the IRSA or control men had microdeletions in the AZFa, AZFb, or AZFc regions. A total of nine previous studies examined the relationship between Y chromosome microdeletions and IRSA, yielding contradictory results, which we discuss in detail.

CONCLUSION(S)

On the basis of our comparisons, it is unlikely that Y chromosome microdeletions contribute to IRSA and are therefore currently not recommended for the routine evaluation of IRSA couples.

The Association between Y Chromosome Microdeletion and Recurrent Pregnancy Loss

BACKGROUND

To date, the role of male factor contributing in evaluation of spontaneous recurrent pregnancy loss (RPL) has been less investigated and there is discrepancy in the role of Y chromosome microdeltions in RPL. Therefore, the current study was designed to examine whether Y chromosome microdeletions were associated with RPL in an Iranian population.

METHODS

One hundred men from couples, experiencing three or more RPLs, and one hundred normal men from couples with at least one child and no history of miscarriages as control group were included. Genomic DNA was extracted from peripheral blood and tested for Y chromosome microdeletions in AZFa, AZFb and AZFc regions using two multiplex PCR.

RESULTS

None of the men in the case and control groups had any microdeletions in the AZFa, AZFb and AZFc regions.

CONCLUSION

It seems that Y chromosome microdeletion is not associated with recurrent pregnancy loss, therefore performing this test in Iranian couples with RPL is not recommended.

Y chromosome microdeletions in Mexican males of couples with idiopathic recurrent pregnancy loss

AIM

To analyze the presence of Y chromosome microdeletions in males of Mexican couples with idiopathic recurrent pregnancy losses (RPL).

METHODS

Seventy-one males from couples with RPL and 66 fertile males as controls were studied. DNA was isolated from peripheral lymphocytes and used to run multiplex polymerase chain reactions. Regions AZFa (sY84, sY86), AZFb (sY127, sY134) and AZFc (sY254, sY255) of the Y chromosome were analyzed according to valid guidelines recommended by the European Academy of Andrology and the European Molecular Genetics Quality Network. Also, the sequence tagged sites (STSs): DYS262 (sY67), DYS220 (sY129), DYF85S1 (sY150), DYF86S1 (sY152) and DYF87S1 (sY153) were included in order to analyze STSs previously reported as deleted. A power analysis to support our simple size was performed.

RESULTS

Results show an absence of Y chromosome microdeletions in males of couples with RPL and controls with an acceptable statistical power.

CONCLUSION

The study did not show an association of recurrent pregnancy loss and Y chromosome microdeletions in Mexican male partners. Based on the results, the study of Y chromosome microdeletions in couples with RPL is not considered clinically relevant.

Association of sex hormone receptor gene polymorphisms with recurrent pregnancy loss: a systematic review and meta-analysis

OBJECTIVE

To investigate the genetic association between estrogen and progesterone receptor polymorphisms (ER, PR) and skewed X chromosome inactivation (XCI) and idiopathic recurrent pregnancy loss (RPL).

DESIGN

A systematic review and meta-analysis using electronic database (MEDLINE and EMBASE) up to April 2011.

SETTING

24 eligible studies from 14 countries.

PATIENT(S)

2,750 RPL patients and 3,123 controls were included.

INTERVENTION(S)

Meta-analyses by means of random-effects models.

MAIN OUTCOME MEASUREMENT(S)

Common polymorphisms of ER and PR and skewed XCI.

RESULT(S)

Of 221 potentially relevant studies, 24 case-control studies were included: 6 reports of PR polymorphisms (PROGINS), 6 reports of ER-α (3 each of rs2234693 [PvuII], rs9340799 [XbaI], and B domain) and 12 reports of skewed XCI. The integrated result showed that women with skewed XCI (>90%) had a higher risk for RPL (the summary OR [95% CI]: 2.43 [1.34-4.43]), and the subgroup analysis of those studies that included more than three consecutive miscarriages (5 studies), also showed a significant association with RPL (2.52 [1.16-5.44]). Among studies of PR (PROGINS) and ER (PuvII, XbaI, B domain) polymorphisms in RPL, the summary ORs were 1.46 (0.56-3.79), 0.90 (0.47-1.75), 0.83 (0.53-1.29), and 1.07 (0.43-2.63), respectively.

CONCLUSION(S)

Meta-analyses of the available data showed a significant association between skewed XCI and idiopathic RPL. More data on the associations between ER and PR polymorphisms and RPL would be helpful to elucidate their roles in RPL.

The expression of Fas/FasL and apoptosis in yak placentomes

To clarify the status and distribution of Fas and Fas-Ligand (FasL) in yak's placentomes, immunohistochemistry (IHC) was carried out to analyze the expression and location of Fas and FasL in paraffin embedded sections. The area of positive stained sites was selected and measured using image analyses software (Image Pro-Plus 6.0). So the positive index (PI) was calculated to estimate the intensity of protein expression according to the percentage of positive area in corresponding compartment of the placentomes. In cotyledonary villi, Fas mainly presented on the villous trophoblast cells in early pregnancy. The positive index reached a maximum of 20.7±8.8 at the third month of pregnancy. Then Fas was declined rapidly along with the progress of gestation and the value was 2.8±1.3 after the 7th month of pregnancy. However, in caruncular crypts, Fas was mainly localized to isolated cells or clustered cells of the uterine stroma underlying the caruncular epithelium. The intensity was lower and the positive index was changed between 4.7±0.9 and 8.5±1.6 throughout gestation. For FasL, it gave a distinct immunostained distribution. In cotyledonary villi, FasL was localized dominantly and strongly in the cytoplasm of binuclear, mononuclear and trinuclear trophoblast giant cells (TGC). The positive index of FasL maintained a moderate level all through the gestation. In caruncular crypts, the expression of FasL was weak and the positive index was declined. Only in the first two months, maternal uterine epithelial cells intensely expressed FasL and the index reached to the maximum of 19.8±5.2. The result of subcellular localization of Fas ligand using immunoelectron microscopy technology indicated that FasL was subcellular located in some intracellular vesicles of TGC. This means the vesicles of trophoblast giant cells itself can express FasL. By the TUNEL method, apoptosis was detected in yak placentomes. The amount of apoptotic cells was rare. The fetal chorionic trophoblast cells and caruncular crypt epithelium cells demonstrated higher percentage of apoptosis in middle pregnancy, which suggested that apoptosis plays an important role in placental cellular regeneration. In addition, the apoptosis of maternal caruncular stromal cells provides a local mechanism for maternal immunotolerance to the fetus and this mechanism was mediated by Fas-FasL pathway.

Y chromosome microdeletions, sperm DNA fragmentation and sperm oxidative stress as causes of recurrent spontaneous abortion of unknown etiology

BACKGROUND

The aim of the present study was to evaluate the implication of male factor, in terms of sperm DNA oxidation and fragmentation, and Y chromosome microdeletions in recurrent spontaneous abortion (RSA) of unknown origin in a strictly selected cohort.

METHODS

A prospective cohort study was carried out in a private university-affiliated setting. Three groups, each comprised of 30 males, were compared. The first was formed by healthy and fertile sperm donors (SD) with normal sperm parameters (control group), the second by men presenting severe oligozoospermia (SO) without RSA history, and the third by men from couples who had experienced idiopathic RSA. Frequency of Y chromosome microdeletions and mean sperm DNA fragmentation and oxidation were determined.

RESULTS

Y chromosome microdeletions were not detected in any of the males enrolled in the study. Moreover, sperm DNA oxidation measurements were not demonstrated to be relevant to RSA. Interestingly, sperm DNA fragmentation was higher in the SO group than in the RSA and the SD groups, and also higher in the RSA group compared with the SD group, but lacked an adequate predictive power to be employed as a discriminative test of RSA condition.

CONCLUSIONS

Sperm DNA features and Y chromosome microdeletions do not seem to be related to RSA of unknown origin. Other molecular features of sperm should be studied to determine their possible influence on RSA. Clinicaltrials.gov reference: NCT00447395.

Recurrent first trimester pregnancy loss: revised definitions and novel causes

PURPOSE OF REVIEW

First trimester pregnancy loss affects up to 15% of clinically recognized pregnancies. Whereas most couples will proceed to have successful subsequent pregnancies, 2-4% will suffer recurrent losses, often with no identifiable cause. In fact, up to 40-50% of patients suffering recurrent pregnancy loss (RPL) will have no identifiable cause for their losses. Whereas the high incidence of spontaneous fetal aneuploidy will ensure that this number will never fall to zero, its level suggests that additional causes and appropriate diagnostic testing await discovery. The definition, diagnostic work-up and appropriate interventions among patients with RPL remain controversial. Here, we will review those papers published in the last 1-2 years that improve our understanding of the definition of RPL, that confirm the utility of present testing paradigms or that pose novel causes and diagnostic approaches to patients with a history of RPL.

RECENT FINDINGS

Standard definitions of RPL have been suggested by the American Society of Reproductive Medicine. Suggested potential diagnostic testing for RPL has been expanded to include male factors and new paradigms that address placental function, including the role of vascular endothelial growth factor, thrombosis and maternal-fetal immunology.

SUMMARY

Standardized definitions for RPL and standardized approaches to initiating the RPL work-up will aid in study design and improve the applicability and implications of published findings. Appropriate investigation of novel causes for RPL may decrease the percentage of patients carrying the diagnosis of unexplained RPL.