Reproductive outcome after PGD in couples with recurrent miscarriage carrying a structural chromosome abnormality: a systematic review

Preimplantation genetic testing in couples with balanced chromosome rearrangement: a four-year period real world retrospective cohort study

BACKGROUND

Couples with balanced chromosome rearrangement (BCR) are at high risk of recurrent miscarriages or birth defects due to chromosomally abnormal embryos. This study aimed to provide real-world evidence of the euploidy rate of blastocysts from couples with BCR using preimplantation genetic testing (PGT) and to guide pretesting genetic counselling.

METHODS

A continuous four-year PGT data from couples with BCR were retrospectively analyzed. Biopsied trophectoderm cells were amplified using whole genome amplification, and next-generation sequencing was performed to detect the chromosomal numerical and segmental aberrations. Clinical data and molecular genetic testing results were analyzed and compared among the subgroups.

RESULTS

A total of 1571 PGT cycles with 5942 blastocysts were performed chromosomal numerical and segmental aberrations detection during the four years. Of them, 1034 PGT cycles with 4129 blastocysts for BCR couples were included; 68.96% (713/1034) PGT cycles had transferable euploid embryos. The total euploidy rate of blastocysts in couples carrying the BCR was 35.29% (1457/4129). Couples with complex BCR had euploid blastocyst rates similar to those of couples with non-complex BCR (46.15% vs. 35.18%, P > 0.05). Chromosome inversion had the highest chance of obtaining a euploid blastocyst (57.27%), followed by Robertsonian translocation (RobT) (46.06%), and the lowest in reciprocal translocation (RecT) (30.11%) (P < 0.05). Couples with males carrying RobT had higher rates of euploid embryo both in each PGT cycles and total blastocysts than female RobT carriers did, despite the female age in male RobT is significant older than those with female RobT (P < 0.05). The proportions of non-carrier embryos were 52.78% (95/180) and 47.06% (40/85) in euploid blastocysts from couples with RecT and RobT, respectively (P > 0.05). RecT had the highest proportion of blastocysts with translocated chromosome-associated abnormalities (74.23%, 1527/2057), followed by RobT (54.60%, 273/500) and inversion (30.85%, 29/94) (P < 0.05).

CONCLUSIONS

In couples carrying BCR, the total euploidy rate of blastocysts was 35.29%, with the highest in inversion, followed by RobT and RecT. Even in couples carrying complex BCR, the probability of having a transferable blastocyst was 46.15%. Among the euploid blastocysts, the non-carrier ratios in RecT and RobT were 52.78% and 47.06%, respectively. RecT had the highest proportion of blastocysts with translocated chromosome-associated abnormalities.

Investigation and Management of Recurrent Pregnancy Loss: A Comprehensive Review of Guidelines

Importance

Recurrent pregnancy loss (RPL) is one of the most frustrating clinical entities in reproductive medicine requiring not only diagnostic investigation and therapeutic intervention, but also evaluation of the risk for recurrence.

Objective

The aim of this study was to review and compare the most recently published major guidelines on investigation and management of RPL.

Evidence Acquisition

A descriptive review of guidelines from the Royal College of Obstetricians and Gynaecologists, the European Society of Human Reproduction and Embryology, the American Society for Reproductive Medicine, the French College of Gynecologists and Obstetricians, and the German, Austrian, and Swiss Society of Gynecology and Obstetrics on RPL was carried out.

Results

There is consensus among the reviewed guidelines that the mainstays of RPL investigation are a detailed personal history and screening for antiphospholipid syndrome and anatomical abnormalities of the uterus. In contrast, inherited thrombophilias, vaginal infections, and immunological and male factors of infertility are not recommended as part of a routine RPL investigation. Several differences exist regarding the necessity of the cytogenetic analysis of the products of conception, parental peripheral blood karyotyping, ovarian reserve testing, screening for thyroid disorders, diabetes or hyperhomocysteinemia, measurement of prolactin levels, and performing endometrial biopsy. Regarding the management of RPL, low-dose aspirin plus heparin is indicated for the treatment of antiphospholipid syndrome and levothyroxine for overt hypothyroidism. Genetic counseling is required in case of abnormal parental karyotype. The Royal College of Obstetricians and Gynaecologists, the European Society of Human Reproduction and Embryology, and the French College of Gynecologists and Obstetricians guidelines provide recommendations that are similar on the management of cervical insufficiency based on the previous reproductive history. However, there is no common pathway regarding the management of subclinical hypothyroidism and the surgical repair of congenital and acquired uterine anomalies. Use of heparin for inherited thrombophilias and immunotherapy and anticoagulants for unexplained RPL are not recommended, although progesterone supplementation is suggested by the American Society for Reproductive Medicine and the German, Austrian, and Swiss Society of Gynecology and Obstetrics.

Conclusions

Recurrent pregnancy loss is a devastating condition for couples. Thus, it seems of paramount importance to develop consistent international practice protocols for cost-effective investigation and management of this early pregnancy complication, with the aim to improve live birth rates.

Recurrent Miscarriage: Diagnostic and Therapeutic Procedures. Guideline of the DGGG, OEGGG and SGGG (S2k-Level, AWMF Registry No. 015/050, May 2022)

Purpose The aim of this guideline is to standardize the diagnosis and therapy of recurrent miscarriage (RM) using evidence from the recent literature. This is done by using consistent definitions, objective evaluations and standardized treatment protocols.

Methods When this guideline was compiled, special consideration was given to previous recommendations in prior versions of this guideline and the recommendations of the European Society of Human Reproduction and Embryology, the Royal College of Obstetricians and Gynecologists, the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine, and a detailed individual search of the literature about the different topics was carried out.

Recommendations Recommendations about the diagnostic and therapeutic procedures offered to couples with RM were developed based on the international literature. Special attention was paid to known risk factors such as chromosomal, anatomical, endocrinological, physiological coagulation, psychological, infectious and immune disorders. Recommendations were also developed for those cases where investigations are unable to find any abnormality (idiopathic RM).

Systematic review of subsequent pregnancy outcomes in couples with parental abnormal chromosomal karyotypes and recurrent pregnancy loss

OBJECTIVE

To evaluate the current evidence of pregnancy outcomes among couples with recurrent pregnancy loss (RPL) with abnormal karyotypes vs. those with normal karyotypes and among couples with RPL and abnormal karyotypes after receiving expectant management vs. preimplantation genetic diagnosis (PGD).

DESIGN

Systematic review and meta-analysis.

SETTING

Academic medical centers.

PATIENT(S)

Pregnancy outcomes in 6,301 couples with RPL who conceived without medical intervention in 11 studies were analyzed. However, only 2 studies addressed the outcomes of couples with RPL and abnormal karyotypes after expectant management (75 cases) vs. PGD (50 cases).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The pregnancy outcomes in couples with RPL with abnormal and normal karyotypes across included studies were evaluated.

RESULT(S)

Compared with those with a normal karyotype, a significantly lower first pregnancy live birth rate (LBR) was found in couples with RPL with abnormal karyotypes (58.5% vs. 71.9%; odds ratio [OR], 0.55; 95% confidence interval [CI], 0.46-0.65; I² =27%). A markedly decreased first pregnancy LBR was found in couples with a translocation (52.9% vs. 72.4%; OR, 0.44; 95% CI, 0.31-0.61; I² =33%) but not in couples with an inversion. However, the differences in accumulated LBR (81.4% vs. 74.8%; OR, 0.96; 95% CI, 0.90-1.03; I² = 0) were nonsignificant, whereas the miscarriage rate was distinctly higher in couples with RPL and abnormal karyotypes (53.0% vs. 34.7%; OR, 2.21; 95% CI, 1.69-2.89; I² = 0). Compared with those who chose expectant management, differences in accumulated LBR were nonsignificant (60% vs. 68%; OR, 0.55; 95% CI, 0.11-2.62; I² =71%), whereas the miscarriage rate (24% vs. 65.3%; OR, 0.15; 95% CI, 0.04-0.51; I² = 45) was markedly low in couples with RPL and abnormal karyotypes who chose PGD.

CONCLUSION(S)

Couples with RPL and abnormal karyotypes had a higher miscarriage rate than couples with normal karyotypes but achieved a noninferior accumulated LBR through multiple conception attempts. In couples with RPL and abnormal karyotypes, PGD treatment did not increase the accumulated LBR but markedly reduced miscarriage rate compared with expectant management.

PGT for structural chromosomal rearrangements in 300 couples reveals specific risk factors but an interchromosomal effect is unlikely

RESEARCH QUESTION

What factors affect the proportion of chromosomally balanced embryos in structural rearrangement carriers? Is there any evidence for an interchromosomal effect (ICE)?

DESIGN

Preimplantation genetic testing outcomes of 300 couples (198 reciprocal, 60 Robertsonian, 31 inversion and 11 complex structural rearrangement carriers) were assessed retrospectively. Blastocysts were analysed either by array-comparative genomic hybridization or next-generation sequencing techniques. ICE was investigated using a matched control group and sophisticated statistical measurement of effect size (φ).

RESULTS

300 couples underwent 443 cycles; 1835 embryos were analysed and 23.8% were diagnosed as both normal/balanced and euploid. The overall cumulative clinical pregnancy and live birth rates were 69.5% and 55.8%, respectively. Complex translocations and female age (≥35) were found to be risk factors associated with lower chance of having a transferable embryo (P < 0.001). Based on analysis of 5237 embryos, the cumulative de-novo aneuploidy rate was lower in carriers compared to controls (45.6% versus 53.4%, P < 0.001) but this was a 'negligible' association (φ < 0.1). A further assessment of 117,033 chromosomal pairs revealed a higher individual chromosome error rate in embryos of carriers compared to controls (5.3% versus 4.9%), which was also a 'negligible' association (φ < 0.1), despite a P-value of 0.007.

CONCLUSIONS

These findings suggest that rearrangement type, female age and sex of the carrier have significant impacts on the proportion of transferable embryos. Careful examination of structural rearrangement carriers and controls indicated little or no evidence for an ICE. This study helps to provide a statistical model for investigating ICE and an improved personalized reproductive genetics assessment for structural rearrangement carriers.

De novo balanced reciprocal translocation mosaic t(1;3)(q42;q25) detected by prenatal genetic diagnosis: a fetus conceived using preimplantation genetic testing due to a t(12;14)(q22;q13) balanced paternal reciprocal translocation

INTRODUCTION

De novo balanced reciprocal translocations mosaicism in fetus conceived using preimplantation genetic testing from a different balanced translocation carrier parent has been rarely reported.

METHODS

Chromosomal microarray analysis, karyotype analysis and fluorescent in situ hybridization were performed to verify the type and heredity of the rearrangement. STR analysis was conducted to identify potential contamination and verify kinship. In addition, a local BLAST engine was performed to locate potentially homologous segments which might contribute to the translocation in breakpoints of chromosome.

RESULTS

A rare de novo balanced reciprocal translocations mosaicism mos 46,XY,t(1;3)(q42;q25)[40]/46,XY[39] was diagnosed in a fetus conceived using preimplantation genetic testing due to a 46,XY,t(12;14)(q22;q13) balanced translocation carrier father through multiplatform genetic techniques. Two of the largest continuous high homology segments were identified in chromosomal band 1q42.12 and 3q25.2. At the 21-months follow up, infant has achieved all psychomotor development milestones as well as growth within the normal reference range.

CONCLUSION

We present a prenatal diagnosis of a rare de novo balanced reciprocal translocations mosaicism in a fetus who conceived by preimplantation genetic testing. The most reasonable driving mechanism was that a de novo mitotic error caused by nonallelic homologous recombination between 1q42.12 and 3q25.2 in a zygote within the first or early cell divisions, which results in a mosaic embryo with the variant present in a half proportion of cells.

Effects of aspirin, vitamin D3, and progesterone on pregnancy outcomes in an autoimmune recurrent spontaneous abortion model

High proportions of placental lymphocytes expressing DX5+/CD25+/FOXP3+/CD45+/CD4+ are beneficial to maintain immune tolerance and improve pregnancy outcomes. This study aimed to compare and evaluate the therapeutic effects of aspirin, vitamin D3 (VitD3), and progesterone on the autoimmune recurrent spontaneous abortion (RSA) model. The autoimmune RSA mouse model was constructed, and the embryo loss rate was calculated for each group. Then, primary mouse placental lymphocytes were isolated, and the expression of DX5+/CD25+/FOXP3+/CD45+/CD4+ was detected through flow cytometry. The serum levels of anti-cardiolipin antibody (ACA), β2-GP1, CXCL6, IFN-γ, and IL-6 were measured by ELISA to evaluate the proportion of Th1 and Th2 cells. Autoimmune RSA significantly increased the embryo loss rate, which was improved by aspirin, VitD3, and progesterone treatment, and progesterone treatment had the best effect among the three treatments. The positive expression of DX5+/CD25+/FOXP3+/CD45+/CD4+ in the VitD3 and progesterone groups was significantly higher than that in the autoimmune RSA group, and the expression was highest in the progesterone treatment group. In the plasma of autoimmune RSA mice, the ACA, β2-GP1, CXCL6, and IFN-γ levels were significantly higher and the IL-6 level was lower than the levels in control mice. All these changes could be reversed by aspirin and progesterone treatment. In conclusion, aspirin, VitD3 and progesterone treatment improved pregnancy outcomes in autoimmune RSA mice by regulating the Th1/Th2 balance and cytokines, and progesterone had the best effect of the three treatments.

Effects of chromosomal abnormalities on pregnancy outcomes in female undergoing artificial insemination with donor's sperm

This study aimed to evaluate the clinical characteristics, pregnancy outcomes and prognostic factors for pregnancy of female with chromosomal abnormalities (CAs) after artificial insemination with donor's sperm (AID) treatment.A retrospective case-control study was analyzed by using the data of 29 female patients with CA and 116 controlled patients with normal karyotype (1:4 ratio) who underwent AID cycles at Guangdong Family Planning Special Hospital from January 2011 to December 2017. In all cases, reproductive histories were collected, and the cytogenetic analysis was performed by Trypsin-Giemsa banding and karyotyping. The embryos were fertilized via intracervical or intrauterine insemination. Clinical characteristic variables were compared.The prevalence of CA was found to be 0.29% in the whole AID population. The live birth rates of CA group and controlled group were 41.4% and 31.0% (P = .29) respectively. Compared to normal karyotype group, patients with CA showed higher rate of primary infertility (93.1% vs 75.9%, P = .049); Multivariate analysis demonstrated that ovarian stimulation (odds ratio, 3.055; 95% confidence interval, 1.421-6.568; P = .004) was associated with adverse pregnancy outcomes in female patients with AID treatment.For the infertility CA patients who were phenotypically normal, AID was a suitable choice, whereas ovarian stimulation results in an improvement in the pregnancy rate.

Genetic testing of products of conception in recurrent pregnancy loss evaluation

Genetic testing of products of conception (POC) has been proposed as a tool to be used in the evaluation of patients with recurrent pregnancy loss (RPL). Following a complete RPL evaluation, POC results may reveal an aneuploidy and provide an explanation for the miscarriage in more than 55% of cases. When the cytogenetic result of the pregnancy loss reveals a euploid pregnancy, management should be directed towards the identification of treatable abnormalities. Furthermore, the results of POC testing might better define a subgroup of patients with unexplained RPL who may benefit from expectant management versus preimplantation genetics (aneuploid unexplained RPL) or investigational therapy (euploid unexplained RPL).

Blastocyst conversion rate and ploidy in patients with structural rearrangements

OBJECTIVE

The primary objective of this study was to test the hypotheses that compared to IVF cycles undergoing preimplantation genetic testing for aneuploidy (PGT-A) with or without testing for monogenic disorders (PGT-M), IVF cycles undergoing PGT for structural rearrangements (PGT-SR) will have (1) a poorer blastocyst conversion rate and (2) fewer usable blastocysts available for transfer. Secondarily, the study aimed to compare pregnancy outcomes among PGT groups.

PATIENTS

Retrospective cohort study including cycles started from January 1, 2012, to March 30, 2020, with the intent of pursuing PGT-A, PGT-A with PGT-M, and PGT-SR, with trophectoderm biopsy on days 5 or 6.

RESULTS

A total of 658 women underwent 902 cycles, including 607 PGT-A, 216 PGT-A&M, and 79 PGT-SR cycles. When compared with the blastocyst conversion rate for the PGT-A group (59.4%), and after adjustment for patient age, total number of mature oocytes, BMI, and ICSI, there were no significant differences for either the PGT-A&M (69.7%, aRR 1.03, 95% CI 0.96-1.10) or PGT-SR (63.2%, aRR1.04, 95% CI 0.96-1.13) groups. Compared to the PGT-A group, the proportion of usable blastocysts was statistically significantly lower in the PGT-SR group: 35.1% versus 24.4% (aRR 0.57, 95% CI 0.46-0.71) and the PGT-A&M group: 35.1% versus 31.5% (aRR 0.68, 95% CI 0.58-0.81). Implantation, pregnancy, and miscarriage rates were equivalent for all groups.

CONCLUSION

Patients with structural rearrangements have similar blastocyst development but significantly fewer usable blastocysts available for transfer compared to PGT-A testers. Nevertheless, with the transfer of a usable embryo, PGT-SR testers perform as well as those testing for PGT-A.

The Impact of Third Party Reproduction on Family and Kinship

The development of in vitro fertilization (IVF) in the UK, in 1978, proved a major breakthrough in the process of human reproduction, which had remained constant in human history. The impact of IVF and the ensuing assisted reproductive technologies (ARTs) has not been limited in revolutionizing the "natural" practice of biological reproduction, but has reached out to and affected almost every institution in society. Family and kinship, as the social expression of reproduction and the institutions which are the most transparently structured realm of human life are those most profoundly affected by ARTs. Although literature on the implications of ARTs is in general abundant, this article presents new insights on their impact on family and kinship in Iran, which remains a unique case in the Muslim world. It explores the particular way ARTs, especially third-party donation, have been endorsed and practiced in Iran, and their consequences for the family, the infertile individuals, and their position vis-à-vis their kin and social group. The conclusion points to the lack of clarity concerning the initial rulings by the Islamic jurists, who allowed the practice of ARTs, and which has led to a number of unintended consequences regarding the legal, religious, cultural, and ethical issues, affecting the family, its structure and the relationship between the kin group. These consequences range, inter alia, from the question of the anonymity of third-party donor, to the permissibility of gamete donation between blood relatives, and to the absence of enforceable legislation.

The Clinical Effectiveness of Preimplantation Genetic Diagnosis for Chromosomal Translocation Carriers: A Meta-analysis

Published data on the relationship between pregnancy outcomes of preimplantation genetic diagnosis (PGD) in translocation carriers have implicated inconclusive results. To identify potentially eligible reports, an electronic search was conducted in several databases, including PubMed, Scopus, Web of Knowledge, and Cochrane. Pooled odd ratios (ORs) and 95% confidence intervals (Cis) were estimated based on a random-effect model to evaluate the strength of association between PGD and successful pregnancy outcome in translocation carriers. A total of six cohort studies were included in the current study. The meta-analysis of these studies revealed that the PGD method was associated with an increased successful pregnancy outcome of translocation carriers (OR = 8.58; 95%CI: 1.40–52.76). In subgroup analysis, there was no significant association according to the chromosomal translocation carrier origin and the type of translocated chromosomes, as well as country. In developed countries, the pregnancy outcome of PGD was significantly improved in translocation carriers (OR = 21.79; 95%CI: 1.93–245.52). The current meta-analysis demonstrated that the PGD method is associated with successful pregnancy outcome in both types of reciprocal and Robertsonian translocation carriers, especially in developed countries.

Expectant management and live birth outcomes for male balanced-translocation carriers: Two case reports and a literature review

RATIONALE

Couples with male balanced-translocation carriers may experience recurrent pregnancy loss (RPL). Although the expectant management of RPL has developed over many years, genetic counseling for RPL couples with male balanced-translocation carriers remains challenging. Here, we describe the expectant management of 2 male carriers of balanced translocations.

PATIENT CONCERNS

A 32-year-old and a 28-year-old man presented at the clinic with diagnoses of infertility following spontaneous abortions by their wives.

DIAGNOSIS

Both patients had normal semen diagnosed by routine semen analysis and underwent cytogenetic diagnoses.

INTERVENTIONS

Following genetic counseling and informed consent, both couples voluntarily chose expectant management with natural conception.

OUTCOMES

One couple experienced 2 natural pregnancies, the first of which ended in spontaneous abortion and the second produced a phenotypically normal infant. The other couple's first pregnancy resulted in a fetus with a balanced translocation confirmed by amniocentesis and cytogenetic analysis.

LESSONS

Expectant management with natural conception may be an alternative to genetic counseling in male balanced-translocation carriers with RPL, especially those who are reluctant to undergo preimplantation diagnosis.

Genome Sequencing Explores Complexity of Chromosomal Abnormalities in Recurrent Miscarriage

Recurrent miscarriage (RM) affects millions of couples globally, and half of them have no demonstrated etiology. Genome sequencing (GS) is an enhanced and novel cytogenetic tool to define the contribution of chromosomal abnormalities in human diseases. In this study we evaluated its utility in RM-affected couples. We performed low-pass GS retrospectively for 1,090 RM-affected couples, all of whom had routine chromosome analysis. A customized sequencing and interpretation pipeline was developed to identify chromosomal rearrangements and deletions/duplications with confirmation by fluorescence in situ hybridization, chromosomal microarray analysis, and PCR studies. Low-pass GS yielded results in 1,077 of 1,090 couples (98.8%) and detected 127 chromosomal abnormalities in 11.7% (126/1,077) of couples; both members of one couple were identified with inversions. Of the 126 couples, 39.7% (50/126) had received former diagnostic results by karyotyping characteristic of normal human male or female karyotypes. Low-pass GS revealed additional chromosomal abnormalities in 50 (4.0%) couples, including eight with balanced translocations and 42 inversions. Follow-up studies of these couples showed a higher miscarriage/fetal-anomaly rate of 5/10 (50%) compared to 21/93 (22.6%) in couples with normal GS, resulting in a relative risk of 2.2 (95% confidence interval, 1.1 to 4.6). In these couples, this protocol significantly increased the diagnostic yield of chromosomal abnormalities per couple (11.7%) in comparison to chromosome analysis (8.0%, chi-square test p = 0.000751). In summary, low-pass GS identified underlying chromosomal aberrations in 1 in 9 RM-affected couples, enabling identification of a subgroup of couples with increased risk of subsequent miscarriage who would benefit from a personalized intervention.

Clinical Features of Infertile Men Carrying a Chromosome 9 Translocation

Previous studies indicated that chromosome 9 translocations are involved in reduced male fertility and increased chance of miscarriage in the female partner. The aim of this study was to review the clinical features and genetic counselling requirements of infertile men carrying chromosome 9 translocations. This study analyzed fertile-age male carriers of chromosome 9 translocations, and included 12 clinical cases in our hospital. In our cases, three cases had oligozoospermia or severe oligozoospermia, while nine cases had normal semen. Of the latter nine cases, seven were associated with recurrent spontaneous abortions, and two produced a phenotypically normal child as confirmed by amniocentesis. Male chromosome 9 translocations and specific breakpoints from reported papers were searched using PubMed and CNKI database. A literature review identified 76 male patients who carried chromosome 9 translocations. Breakpoints at 9p12, 9p11, 9p10 and 9q34.1 were related to pregestational infertility, while breakpoints at 9p21, 9q10, 9q11, 9q13, 9q21.1, 9q22, 9q22.2, 9q22.3, 9q34, 9q34.2 and 9q34.3 exhibited gestational infertility. Chromosome translocations involving chromosome 9 lead to increased risk of miscarriage. Carriers of chromosome 9 translocations should be counselled to consider in vitro fertilization accompanied by preimplantation genetic diagnosis.

Pregnancy outcomes of reciprocal translocation carriers with two or more unfavorable pregnancy histories: before and after preimplantation genetic testing

PURPOSE

To report the normal live birth and birth defect rates pre- and post- preimplantation genetic testing for chromosomal structural rearrangements (PGT-SR) in reciprocal translocation carriers who have experienced two or more unfavorable pregnancy histories.

METHODS

We conducted a retrospective cohort study of 194 couples who underwent 265 PGT-SR cycles between January 2013 and August 2016. The rates of miscarriage, normal live birth, and birth defect pre- and post- PGT-SR treatment were recorded. The types of birth defect were also categorized.

RESULTS

Before PGT-SR treatment, the 194 couples with reciprocal translocation had a previous reproductive history consisting of 592 pregnancies in total: 496 (83.8%) were miscarriages; 29 (4.9%) ended by induced abortion due to unintended pregnancy; 36 (6.1%) had birth defects; and 17 (2.9%) were normal live births. After PGT-SR treatment, there were 118 clinical pregnancies. Of these pregnancies, 13 (11.0%) were miscarriages, 101 (85.6%) were normal live births, and 4 (3.4%) had birth defects. In total, 14 different disorders were noted in the prenatal and postnatal examinations. Before the PGT-SR treatment, multiple birth defects, central nervous system abnormalities, and congenital heart defects were the three most common congenital malformations. Excluding for methylmalonic acidemia, there were only single and mild birth defects after the PGT-SR treatment.

CONCLUSIONS

After the PGT-SR treatment, the reciprocal translocation carriers who had previously experienced two or more unfavorable pregnancy outcomes had a low risk of miscarriages and birth defects. The rate of normal live births per pregnancy was higher after PGT-SR treatment.

Potential genetic causes of miscarriage in euploid pregnancies: a systematic review

BACKGROUND

Approximately 50% of pregnancy losses are caused by chromosomal abnormalities, such as aneuploidy. The remainder has an apparent euploid karyotype, but it is plausible that there are cases of pregnancy loss with other genetic aberrations that are not currently routinely detected. Studies investigating the use of exome sequencing and chromosomal microarrays in structurally abnormal pregnancies and developmental disorders have demonstrated their clinical application and/or potential utility in these groups of patients. Similarly, there have been several studies that have sought to identify genes that are potentially causative of, or associated with, spontaneous pregnancy loss, but the evidence has not yet been synthesized.

OBJECTIVE AND RATIONALE

The objective was to identify studies that have recorded monogenic genetic contributions to pregnancy loss in euploid pregnancies, establish evidence for genetic causes of pregnancy loss, identify the limitations of current evidence, and make recommendations for future studies. This evidence is important in considering additional research into Mendelian causes of pregnancy loss and appropriate genetic investigations for couples experiencing recurrent pregnancy loss.

SEARCH METHODS

A systematic review was conducted in MEDLINE (1946 to May 2018) and Embase (1974 to May 2018). The search terms ‘spontaneous abortion’, ‘miscarriage’, ‘pregnancy loss’, or ‘lethal’ were used to identify pregnancy loss terms. These were combined with search terms to identify the genetic contribution including ‘exome’, ‘human genome’, ‘sequencing analysis’, ‘sequencing’, ‘copy number variation’, ‘single-nucleotide polymorphism’, ‘microarray analysis’, and ‘comparative genomic hybridization’. Studies were limited to pregnancy loss up to 20 weeks in humans and excluded if the genetic content included genes that are not lethal in utero, PGD studies, infertility studies, expression studies, aneuploidy with no recurrence risk, methodologies where there is no clinical relevance, and complex genetic studies. The quality of the studies was assessed using a modified version of the Newcastle–Ottawa scale.

OUTCOMES

A total of 50 studies were identified and categorized into three themes: whole-exome sequencing studies; copy number variation studies; and other studies related to pregnancy loss including recurrent molar pregnancies, epigenetics, and mitochondrial DNA aberrations. Putatively causative variants were found in a range of genes, including CHRNA1 (cholinergic receptor, nicotinic, alpha polypeptide 1), DYNC2H1 (dynein, cytoplasmic 2, heavy chain 1), and RYR1 (ryanodine receptor 1), which were identified in multiple studies. Copy number variants were also identified to have a causal or associated link with recurrent miscarriage.

WIDER IMPLICATIONS

Identification of genes that are causative of or predisposing to pregnancy loss will be of significant individual patient impact with respect to counselling and treatment. In addition, knowledge of specific genes that contribute to pregnancy loss could also be of importance in designing a diagnostic sequencing panel for patients with recurrent pregnancy loss and also in understanding the biological pathways that can cause pregnancy loss.

Review of current guidelines for recurrent pregnancy loss: new strategies for optimal evaluation of women who may be superfertile

The current evidence-based guidelines for the evaluation of recurrent pregnancy loss recommended by the American Society for Reproductive Medicine and by the European Society of Human Reproduction and Embryology are compared and contrasted in this review. The clinical use of either of these guidelines will result in a probable diagnosis for only half of the affected patients. New strategies for a full evaluation of recurrent pregnancy loss incorporating 24- chromosome microarary on the products of conception offer more explanations for patients and caregivers. This new algorithm should decrease the use of empiric, unproven treatments. Combining the results of genetic testing on the miscarriage tissue with the conventional diagnostic tests has made it possible to explain the etiology of pregnancy loss in more than 90% of the cases. This cost-saving strategy can decrease the emotional distress and frustration for both couples and physicians when it comes to management of recurrent pregnancy loss.

Genetic abnormalities and pregnancy loss

Genetic abnormalities, whether occurring in the conceptus or the parents, can predispose to sporadic or recurrent pregnancy loss (RPL). Abnormalities in the conceptus include aneuploidy, copy number changes, skewed X inactivation, and single gene disorders or mutations. Among parents who suffer RPL, the best studied genetic cause is balanced chromosomal translocations. For evaluation of genetic abnormalities in cases of pregnancy loss, chromosomal microarray is more likely to yield interpretable results than karyotype due to cell culture failure. For parents, karyotype remains the standard since microarray may not detect truly balanced translocations. For those with an identified underlying genetic abnormality, preimplantation genetic testing has been proposed to optimize the live birth rate. This approach shows promise, but currently lacks supporting evidence. In summary, various genetic causes for recurrent pregnancy loss are known, but when such a cause is identified, the implications for management remain unclear.

Differential gene expression profile in monocytic myeloid-derived suppressor cells at maternal-fetal interface in a mouse model of spontaneous abortion

ABSTRACTBACKGROUND

Monocytic myeloid-derived suppressor cells (MO-MDSCs) play an important role in maintaining normal pregnancy. However, it is still not clear what kind of changes in MO-MDSCs may lead to miscarriage, and which gene expression changes take place when MO-MDSCs migrate to the uterus as bone marrow-derived cells.

METHODS

We used flow sorting technology to obtain MO-MDSCs from the maternal-fetal interface and bone marrow, respectively. Affymetrix 3'IVT expression profiling chip technology was used to detect the differential gene expression profiles in MO-MDSCs at the maternal-fetal interface in a mouse model of spontaneous abortion compared with the normal fertility control mice. We also compared the differential gene expression of MO-MDSCs at the maternal-fetal interface compared with bone marrow in the normal fertility control mice.

RESULTS

We found that 3,409 genes in MO-MDSCs were upregulated and 1,539 genes were downregulated at the maternal-fetal interface in the spontaneous abortion mice compared with the normal fertility mice. These genes are enriched in cellular components, biological processes, molecular functions, and protein binding, tumor signaling pathway, the PI3K-Akt signaling pathway, intratumoral proteoglycans, and extracellular matrix receptor interactions. Furthermore, we found that 270 genes in MO-MDSCs were upregulated and 383 genes were downregulated at the maternal-fetal interface in the normal fertility mice compared with those in the bone marrow. These genes are enriched in cellular components, biological processes, molecular functions, cell cycle, tumor transcriptional disorder, and cell adhesion molecules.

CONCLUSION

Differential gene expression in MO-MDSCs likely contributes to a successful pregnancy in fetal-maternal immunotolerance.

A Familial Small Supernumerary Marker Chromosome 15 Associated with Cryptic Mosaicism with Two Different Additional Marker Chromosomes Derived de novo from Chromosome 9: Detailed Case Study and Implications for Recurrent Pregnancy Loss

We report a case of familial small supernumerary marker chromosome 15 in a phenotypically normal female with 4 recurrent spontaneous abortions and a healthy child. The initial karyotype showed a small, bisatellited, apparently metacentric marker chromosome, 47,XX,+idic(15)(q11.1), maternally inherited. The proband's mother was mosaic for the idic(15)(q11.1) without pregnancy loss. Reexamination of the proband's karyotype revealed cryptic mosaicism for 1 ring and 1 minute chromosome derived de novo from chromosome 9 in 2% of the metaphases. In FISH analysis, the patient's karyotype was mos 47,XX,+idic(15)(q11.1)mat[100]/49,XX,+idic(15)(q11.1)mat,+r(9;9;9;9),+der(9)dn[2]. The second spontaneous abortion had trisomy 9 (47,XX,+9); the third had mosaic trisomy 9 in 21% of the nuclei and isodicentric chromosome 15 in 36% of the nuclei (mos 48,XN,+9,+idic(15)(q11.1)/47,XN,+9/47,XN,+idic(15)(q11.1)/46,XN). The first and fourth abortions were not cytogenetically studied. The cause of the spontaneous abortions in this patient is likely the cryptic mosaicism for ring and minute chromosomes 9, and gonadal mosaicism is most probable, due to the 2 abortions.

Pregnancy outcomes among patients with recurrent pregnancy loss and chromosomal aberration (CA) without PGD

Background:

Recurrent pregnancy loss (RPL) is defined by two or more failed clinical pregnancies. Three to four percent of the couples with RPL have chromosomal aberrations (CA) in at least one partner. The parent’s structural chromosomal abnormalities may cause an unbalanced karyotype in the conceptus which could lead to implantation failure, early or late pregnancy loss, or delivery of a child with severe physical and/or mental disabilities.

Objective:

To compare live birth rates of couples with CA to couples with normal karyotypes and to investigate medical and obstetric characteristics and pregnancy outcomes of couples with CA and RPL who attend an RPL clinic at a tertiary hospital.

Methods:

A retrospective cohort study, including 349 patients with two or more consecutive pregnancy losses. The study group consisted of 52 patients with CA, and the control group consisted of 297 couples with normal karyotype. All patients were evaluated and treated in the RPL clinic at Soroka University Medical Center and had at least one subsequent spontaneous pregnancy.

Results:

The demographic and clinical characteristics were not found to be statistically different between the two groups. The group of carriers of CA had 28/52 (53.8%) live births in their index pregnancy vs. the normal 202/297 (68%) (P=0.067, CI 95%) in the control group. No statistically significant etiology was found between the study group and the control group. A statistically significant difference in live birth rates was found when comparing the total amount of pregnancies [index pregnancy (IP)+post index pregnancy (PIP)] between the study group and the control group (54.16% vs. 67.82%, respectively, P=0.0328).

Conclusion:

Patients with RPL and CA who have spontaneous pregnancies, have a good prognosis (63.4%) of a successful pregnancy with at least one of the pregnancies (index or post index) resulting in a live birth.

Clinical features of carriers of reciprocal chromosomal translocations involving chromosome 2: report of nine cases and review of the literature

OBJECTIVE

To explore the clinical features of carriers of chromosome 2 translocations, enabling informed genetic counseling of these patients.

MATERIALS AND METHODS

Eighty-two male carriers of a translocation who were infertile or receiving fertility counseling were recruited. Cytogenetic analyses were performed using G-banding. A search of PubMed was performed to determine whether the identified translocations on chromosome 2 are involved in male infertility. The relationships of translocation breakpoints with male infertility and recurrent pregnancy loss were analyzed.

RESULTS

Of the 82 translocation carriers, 9 (11%) were carriers of a chromosome 2 translocation. Four cases had oligozoospermia or infertility, while five had normal semen. In an analysis of the literature, 55 patients who were carriers of chromosome 2 translocations were also reviewed. Breakpoints at 2p13 and 2q31 were observed in six patients each, and were the most common. Breakpoints at 2p23, 2p13, 2p11.2, 2q31, and 2q37 were associated to both pre-gestational and gestational infertility, while other breakpoints were associated with gestational infertility.

CONCLUSIONS

All breakpoints at chromosome 2 were correlated with gestational infertility. Carriers of chromosome 2 translocations should therefore receive counseling to continue with natural conception and use of different technologies available via assisted reproductive technology, such as preimplantation genetic diagnosis.

ESHRE guideline: recurrent pregnancy loss

STUDY QUESTION

What is the recommended management of women with recurrent pregnancy loss (RPL) based on the best available evidence in the literature?

SUMMARY ANSWER

The guideline development group formulated 77 recommendations answering 18 key questions on investigations and treatments for RPL, and on how care should be organized.

WHAT IS KNOWN ALREADY

A previous guideline for the investigation and medical treatment of recurrent miscarriage was published in 2006 and is in need of an update.

STUDY DESIGN, SIZE, DURATION

The guideline was developed according to the structured methodology for development of ESHRE guidelines. After formulation of key questions by a group of experts, literature searches and assessments were performed. Papers published up to 31 March 2017 and written in English were included. Cumulative live birth rate, live birth rate and pregnancy loss rate (or miscarriage rate) were considered the critical outcomes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Based on the collected evidence, recommendations were formulated and discussed until consensus was reached within the guideline group. A stakeholder review was organized after finalization of the draft. The final version was approved by the guideline group and the ESHRE Executive Committee.

MAIN RESULTS AND THE ROLE OF CHANCE

The guideline provides 38 recommendations on risk factors, prevention and investigations in couples with RPL, and 39 recommendations on treatments. These include 60 evidence-based recommendations – of which 31 were formulated as strong recommendations and 29 as conditional – and 17 good practice points. The evidence supporting investigations and treatment of couples with RPL is limited and of moderate quality. Of the evidence-based recommendations, only 10 (16.3%) were supported by moderate quality evidence. The remaining recommendations were supported by low (35 recommendations: 57.4%), or very low quality evidence (16 recommendations: 26.2%). There were no recommendations based on high quality evidence. Owing to the lack of evidence-based investigations and treatments in RPL care, the guideline also clearly mentions investigations and treatments that should not be used for couples with RPL.

LIMITATIONS, REASONS FOR CAUTION

Several investigations and treatments are offered to couples with RPL, but most of them are not well studied. For most of these investigations and treatments, a recommendation against the intervention or treatment was formulated based on insufficient evidence. Future studies may require these recommendations to be revised.

WIDER IMPLICATIONS OF THE FINDINGS

The guideline provides clinicians with clear advice on best practice in RPL, based on the best evidence available. In addition, a list of research recommendations is provided to stimulate further studies in RPL. One of the most important consequences of the limited evidence is the absence of evidence for a definition of RPL.

STUDY FUNDING/COMPETING INTEREST(S)

The guideline was developed and funded by ESHRE, covering expenses associated with the guideline meetings, with the literature searches and with the dissemination of the guideline. The guideline group members did not receive payment. J.E. reports position funding from CARE Fertility. S.L. reports position funding from SpermComet Ltd. S.M. reports research grants, consulting and speaker’s fees from GSK, BMS/Pfizer, Sanquin, Aspen, Bayer and Daiichi Sankyo. S.Q. reports speaker’s fees from Ferring. The other authors report no conflicts of interest.

ESHRE Pages are not externally peer reviewed. This article has been approved by the Executive Committee of ESHRE.

Clinical feature of infertile men carrying balanced translocations involving chromosome 10: Case series and a review of the literature

RATIONALE

Infertile male carrying balanced translocations can be broadly divided into two types: pregestational and gestational infertility. Chromosome and breakpoints involved translocation should be considered in genetic counselling for these patients. To date, > 100 cases have been described with carrying balanced translocations involving chromosome 10 in fertile male.

PATIENT CONCERNS

We report 11 cases translocation carriers involving chromosome 10, and review 99 carriers of chromosome 10 translocation from reported literature.

DIAGNOSES

Eleven cases of chromosomal translocation were diagnosed by cytogenetic analysis. Three of these men had azoospermia or oligozoospermia, while eight had normal semen. Of these latter cases, their partners were able to conceive, but had a tendency to miscarry or have a stillbirth.

INTERVENTIONS

Chromosome breakpoints should be considered in genetic counseling. Preimplantation genetic diagnosis should be performed to decrease the high risk of miscarriage and to minimize the genetic risks to offspring for patients with gestational infertility.

OUTCOMES

The most common translocations and breakpoints were at t(4;10) and 10q24, observed in 12 and 10 patients respectively. Breakpoints at 10p15.1, 10p12, 10q10, 10q22.1, 10q24.2, and 10q26.3 were linked to pregestational infertility; breakpoints at 10p12.1, 10q11, 10q21.2, and 10q23.3 were associated with gestational infertility; the other breakpoints were connected with both forms of infertility.

LESSONS

Breakpoints at 10p12 and 10q26.3 were associated with pregestational infertility. Other breakpoints at chromosome 10 were correlated with gestational infertility. These breakpoints should be considered when counseling men with chromosome 10 translocations should be informed of their options.

Role of chemerin/CMKLR1 in the maintenance of early pregnancy

Chemerin is a cytokine that attracts much attention in the reproductive process. This study aimed to explore the effects of chemerin and its receptor chemokine-like receptor 1 (CMKLR1) on the maintenance of early pregnancy. The expression levels of chemerin and CMKLR1 in the decidua tissues of 20 early normal pregnant women and 20 early spontaneous abortion women were examined by Western blot and real-time polymerase chain reaction analyses. CMKLR1 receptor antagonist (α-NETA) was then intrauterinely injected into normal pregnant mice model to assess its effect on the outcome of pregnancy and the phosphorylation rate of ERK1/2 in decidua tissues.We found that the expression level of chemerin in women who had experienced early spontaneous abortion was lower than in those who had experienced normal early pregnancy (P < 0.01); conversely, CMKLR1 expression was higher in the former than in the latter (P < 0.01). In a pregnant-mouse model, the embryo resorption rate of α-NETA group was higher than that in the negative control group (61.5% vs. 10.8%) (P < 0.001). Compared with the control group, ERK1/2 phosphorylation in decidua tissues decreased in the α-NETA-treated group (P < 0.01). These results suggested that the inhibition of the chemerin/CMKLR1 signaling pathway can lead to the abortion of mouse embryos, and that chemerin/CMKLR1 may play an important role in the maintenance of early pregnancy possibly by regulating ERK1/2 phosphorylation.

Does preimplantation genetic diagnosis improve reproductive outcome in couples with recurrent pregnancy loss owing to structural chromosomal rearrangement? A systematic review

Recurrent pregnancy loss (RPL) is a common, yet elusive, complication of pregnancy. Among couples at high risk of RPL, such as those carrying a structural chromosomal rearrangement, preimplantation genetic diagnosis (PGD) has been proposed as a tool to improve live birth rates and reduce the incidence of miscarriage; however, no clear consensus has been reached on its benefits in this population. This systematic review summarizes existing published research on the effect of PGD on pregnancy outcomes among carriers of chromosomal abnormalities with RPL. A comprehensive search of common databases was conducted, which yielded 20 studies. Meta-analysis was precluded owing to significant heterogeneity between studies. The primary outcome of interest was live birth rate (LBR), and a pooled total of 847 couples who conceived naturally had a LBR ranging from 25-71% compared with 26.7-87% among 562 couples who underwent IVF and PGD. Limitations of the study include lack of large comparative or randomized control studies. Patients experiencing RPL with structural chromosomal rearrangement should be counselled that good reproductive outcomes can be achieved through natural conception, and that IVF-PGD should not be offered first-line, given the unproven benefits, additional cost and potential complications associated with assisted reproductive technology.

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.

A report of nine cases and review of the literature of infertile men carrying balanced translocations involving chromosome 5

Background

Balanced translocations may cause the loss of genetic material at the breakpoints and may result in failure of spermatogenesis. However, carriers of reciprocal translocation may naturally conceive. Genetic counseling of male carriers of translocations remains challenging. This study explores the clinical features of carriers of chromosome 5 translocations, enabling informed genetic counseling of these patients.

Results

Of 82 translocation carriers, 9 (11%) were carriers of a chromosome 5 translocation. One case had azoospermia, while three cases had experienced recurrent spontaneous abortions, two cases had each experienced stillbirth, and three cases produced a phenotypically normal child confirmed by amniocentesis. A literature review identified 106 patients who carried chromosome 5 translocations. The most common chromosome 5 translocation was t(4,5), observed in 13 patients. Breakpoint at 5p15 was observed in 11 patients. All breakpoints at chromosome 5 were associated with gestational infertility.

Conclusion

In genetic counseling, physicians should consider chromosome 5 and its breakpoints. Carriers of chromosome 5 translocations may continue with natural conception or use assisted reproductive technologies, such as preimplantation genetic diagnosis.

A Study on Balanced Chromosomal Translocations in Couples with Recurrent Pregnancy Loss

Background:

Recurrent pregnancy loss (RPL) is an obstetric complication that affects couples in their reproductive age. Chromosomal abnormalities, mainly balanced rearrangements, could commonly be present in couples with RPL.

Aim:

The purpose of this study is to evaluate the contribution of chromosomal abnormalities and balanced reciprocal translocations, in particular occurring in either of the partners, resulting in RPL.

Materials and Methods:

A retrospective cytogenetic study was carried out on 152 individuals (76 couples) having a history of RPL. The cases were analyzed using G-banding and fluorescence in situ hybridization, wherever necessary.

Results:

Chromosomal abnormalities were observed in 3.2% of the total RPL cases, of which balanced translocations were observed in 4 (80%) individuals and marker chromosome was detected in 1 (20%) individual. All balanced translocations comprised reciprocal translocations, and no cases of Robertsonian translocations were detected in our study. Among reciprocal translocation carriers, three were male and one was female. Polymorphic variants were noted in 8 (5.3%) individuals.

Conclusions:

Chromosomal analysis is an important etiological investigation in couples with RPL. Balanced translocations are the most commonly detected chromosomal abnormalities in such couples. Thus, these couples are the best candidates for offering prenatal genetic diagnosis, thereby ensuring a better reproductive outcome.

Prevalence and Treatment Choices for Couples with Recurrent Pregnancy Loss Due to Structural Chromosomal Anomalies

OBJECTIVE

Parental carriers of balanced structural chromosomal rearrangements such as reciprocal or Robertsonian translocations are at increased risk of recurrent pregnancy loss (RPL) due to the production of gametes with unbalanced non-viable chromosome variants. As a purported means of improving reproductive outcomes in this population, IVF and preimplantation genetic diagnosis (PGD) have been introduced as an alternative to natural conception and prenatal diagnosis. In this study, we evaluate the prevalence and treatment choices of couples with structural chromosomal rearrangement referred to a tertiary care RPL clinic. In addition, we compare the two methods of management in terms of live birth rate.

METHODS

This is a retrospective chart review of 2321 couples who were referred to a highly specialized RPL clinic for ongoing clinical management between January 2005 and December 2013 (n = 23). Couples who pursued PGD through local fertility centres during this time were also included (n = 13).

RESULTS

Thirty-six couples (1.6%) were found to be parental carriers of a structural chromosomal rearrangement. In this cohort, couples were twice as likely to pursue natural conception compared with IVF with PGD. No significant differences were observed in live birth rate between PGD and clinical management (66.6% vs. 53.3%, P = 0.717). With PGD management, six live birth outcomes were observed, with an incidence of one birth in 5.63 years of follow-up. With clinical management, 24 live birth outcomes were observed, with an incidence of one birth in 4.09 years of follow-up. Mean time to live birth was 17.5 months and 23.3 months in clinical management and PGD, respectively.

CONCLUSIONS

Among couples presenting to a tertiary RPL clinic, parental carriers of structural chromosomal rearrangement and history of RPL are more likely to pursue natural conception over IVF and PGD. With regards to reproductive outcomes, no significant difference in miscarriage rate, time to live birth, or live birth rate was observed between couples who pursued PGD compared with expectant clinical management.

Recurrent Pregnancy Loss: Generally Accepted Causes and Their Management

Recurrent pregnancy loss (RPL), commonly defined as 3 consecutive losses <10 weeks gestation, affects up to 5% of couples. Well-accepted causes include uterine malformation, antiphospholipid syndrome, and parental chromosomal abnormalities; however, the majority of RPL cases are idiopathic (up to 75%). This chapter covers these accepted causes of RPL and provides diagnosis and management strategies for patients falling within the above categories.

Genetic Causes of Recurrent Pregnancy Loss

Pregnancy loss is one of the most common obstetric complications, affecting over 30% of conceptions. A considerable proportion of losses are due to genetic abnormalities. Indeed, over 50% of early pregnancy losses have been associated with chromosomal abnormalities. Most are due to de novo nondisjunctional events but balanced parental translocations are responsible for a small but important percentage of genetic abnormalities in couples with recurrent pregnancy loss. In the past, assessment of genetic abnormalities was limited to karyotype performed on placental or fetal tissue. However, advances in molecular genetic technology now provide rich genetic information about additional genetic causes of and risk factors for pregnancy loss. In addition, the use of preimplantation genetic testing in couples undergoing in vitro fertilization has the potential to decrease the risk of pregnancy loss from genetic abnormalities. To date, efficacy is uncertain but considerable potential remains. This chapter will review what is known about genetic causes of recurrent pregnancy loss with a focus on novel causes and potential treatments. Remaining knowledge gaps will be highlighted.

Recurrent pregnancy loss: current perspectives

Recurrent pregnancy loss is an important reproductive health issue, affecting 2%–5% of couples. Common established causes include uterine anomalies, antiphospholipid syndrome, hormonal and metabolic disorders, and cytogenetic abnormalities. Other etiologies have been proposed but are still considered controversial, such as chronic endometritis, inherited thrombophilias, luteal phase deficiency, and high sperm DNA fragmentation levels. Over the years, evidence-based treatments such as surgical correction of uterine anomalies or aspirin and heparin for antiphospholipid syndrome have improved the outcomes for couples with recurrent pregnancy loss. However, almost half of the cases remain unexplained and are empirically treated using progesterone supplementation, anticoagulation, and/or immunomodulatory treatments. Regardless of the cause, the long-term prognosis of couples with recurrent pregnancy loss is good, and most eventually achieve a healthy live birth. However, multiple pregnancy losses can have a significant psychological toll on affected couples, and many efforts are being made to improve treatments and decrease the time needed to achieve a successful pregnancy. This article reviews the established and controversial etiologies, and the recommended therapeutic strategies, with a special focus on unexplained recurrent pregnancy losses and the empiric treatments used nowadays. It also discusses the current role of preimplantation genetic testing in the management of recurrent pregnancy loss.

Clinical outcomes for couples containing a reciprocal chromosome translocation carrier without preimplantation genetic diagnosis

OBJECTIVE

To evaluate the pregnancy outcomes of couples containing a carrier of a reciprocal chromosome translocation (RCT) after assisted reproductive technology without preimplantation genetic diagnosis.

METHODS

A retrospective study was performed using data for couples with an RCT carrier and control couples with a normal karyotype (1:4 ratio) who underwent assisted reproductive technology cycles at a Chinese fertility center in 2010-2011. The embryos were fertilized via in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Only the first pick-up cycles were used for analysis. Clinical variables were compared.

RESULTS

Compared with the control group (n=164), the RCT group (n=41) had a marginally lower clinical pregnancy rate (46.3% [19/41] vs 54.3% [89/164]), implantation rate (21.7% [23/106] vs 26.9% [118/438]), multiple-gestation pregnancy rate (21.1% [4/19] vs 32.6% [29/89]), and delivery rate (36.6% [15/41] vs 47.6% [78/164]), whereas the spontaneous abortion rate was slightly higher (21.1% [4/19] vs 12.4% [11/89]). However, none of these differences were significant.

CONCLUSION

The clinical outcomes for RCT carriers were acceptable after IVF/ICSI without performing preimplantation genetic diagnosis, indicating that this approach might comprise a feasible alternative fertility treatment for RCT carriers.

Increased apoptosis rate of human decidual cells and cytotrophoblasts in patients with recurrent spontaneous abortion as a result of abnormal expression of CDKN1A and Bax

In the present study, we analyzed the proliferation and apoptosis of trophoblasts and human decidual cells in patients with recurrent spontaneous abortion and the related cellular pathway mechanism. Thirty-four patients with recurrent abortion and 30 healthy pregnant women undergoing planned artificial abortion were selected. The trophoblast and decidual cells were collected by negative pressure aspiration technique. TUNEL method was used to detect the apoptosis rate. Immunohistochemical method was used for detection of TP53 protein. Quantitative real-time PCR was used for detection of the relative expression level of CDKN1A and Bax mRNA. It was found that the cell apoptosis rate in the recurrent miscarriage group was significantly increased and the expression levels of TP53 protein, CDKN1A and Bax mRNA were also significantly increased (p<0.05). In conclusion, the trophoblast and decidual cells of patients with recurrent abortion were obviously apoptotic, which was probably related to abnormal expression of the CDKN1A and Bax genes mediated by TP53 protein through cellular pathways.

Impaired function of trophoblast cells derived from translocated hESCs may explain pregnancy loss in women with balanced translocation (11;22)

PURPOSE

The aim of the study was to study whether the trophoblasts carrying unbalanced translocation 11,22 [t(11;12)] display abnormal expression of trophoblastic genes and impaired functional properties that may explain implantation failure.

METHODS

t(11;22) hESCs and control hESCs were differentiated in vitro into trophoblast cells in the presence of BMP4, and trophoblast vesicles (TBVs) were created in suspension. The expression pattern of extravillous trophoblast (EVT) genes was compared between translocated and control TBVs. The functional properties of the TBVs were evaluated by their attachment to endometrium cells (ECC1) and invasion through trans-well inserts.

RESULTS

TBVs derived from control hESCs expressed EVT genes from functioning trophoblast cells. In contrast, TBVs differentiated from the translocated hESC line displayed impaired expression of EVT genes. Moreover, the number of TBVs that were attached to endometrium cells was significantly lower compared to the controls. Correspondingly, invasiveness of trophoblast-differentiated translocated cells was also significantly lower than that of the control cells.

CONCLUSIONS

These results may explain the reason for implantation failure in couple carriers of t(11;22). They also demonstrate that translocated hESCs comprise a valuable in vitro human model for studying the mechanisms underlying implantation failure.

Outcome of preimplantation genetic diagnosis using FISH analysis for recurrent miscarriage in low-risk reciprocal translocation carriers

OBJECTIVE

To assess PGD outcome using FISH analysis in couples with a history of recurrent miscarriage associated with a parental carrier of reciprocal translocation.

STUDY DESIGN

Couples in whom one partner was a carrier of a reciprocal translocation and had a history of two or more miscarriages and a low risk of a live born offspring with an unbalanced chromosomal rearrangement, underwent PGD treatment between 2000 and 2012.

RESULTS

91 couples started 171 fresh and 11 frozen PGD cycles. Of the fresh cycles, 162 (95%) reached oocyte retrieval and 107 (63%) had embryo transfer. In 14 cycles (8%), surplus embryos were cryopreserved. Pregnancy was achieved in 52 fresh PGD cycles, leading to 20 miscarriages and 32 live births. Eleven frozen embryo transfer cycles resulted in two miscarriages and three live births. The overall live birth rate was 19% per fresh and frozen PGD cycle started (35/182) and miscarriage rate was 39% per pregnancy (22/57). The cumulative live birth rate was 32% per couple (29/91).

CONCLUSION

After PGD for recurrent miscarriage in low-risk reciprocal translocation carriers, the miscarriage risk remains high and chance of live birth is low. For those translocation carriers, natural conception may be a better option.

Evaluation of 1100 couples with recurrent pregnancy loss using conventional cytogenetic, PGD, and PGS: hype or hope

Recurrent pregnancy loss (RPL) is an important clinical problem, mostly resulting from chromosomal or genetic defects, while in 30-60% of cases, it is idiopathic. The aim of this study is to evaluate the frequency and types of chromosomal abnormalities, also pre-implantation genetic diagnosis (PGD) and pre-implantation genetic screening (PGS) outcomes among Iranian couples with RPL. This retrospective study was conducted on 1100 Iranian couples (2200 individuals) with RPL referred to Royan Institute between 2008 and 2014. Karyotyping had been performed using standard cytogenetic techniques. PGD results of RPL patients with abnormal karyotypes and PGS results of RPL patients with normal karyotypes were also analyzed. The frequency of chromosomal abnormalities in these patients was 4.95%. Women demonstrated more abnormalities (6.82%) in comparison to men (3.09%). The successful rate of pregnancy after PGD and PGS was 52 and 18.64%, respectively. The observation of 4.95% chromosomal abnormalities among the patients with RPL could support this hypothesis that there is a direct relationship between chromosomal abnormalities and RPL. More than half of the patients who underwent PGD had successful pregnancy; therefore, this approach can improve the success rate of pregnancy in them. The results of PGS cycles showed that this technique could increase the live birth rate in RPL patients.

Is the resulting phenotype of an embryo with balanced X-autosome translocation, obtained by means of preimplantation genetic diagnosis, linked to the X inactivation pattern?

OBJECTIVE

To examine if a balanced female embryo with X-autosome translocation could, during its subsequent development, express an abnormal phenotype.

DESIGN

Preimplantation genetic diagnosis (PGD) analysis on two female carriers with maternal inherited X-autosome translocations.

SETTING

Infertility center and genetic laboratory in a public hospital.

PATIENT(S)

Two female patients carriers undergoing PGD for a balanced X-autosome translocations: patient 1 with 46,X,t(X;2)(q27;p15) and patient 2 with 46,X,t(X;22)(q28;q12.3).

INTERVENTION(S)

PGD for balanced X-autosome translocations.

MAIN OUTCOME MEASURE(S)

PGD outcomes, fluorescence in situ hybridization in biopsied embryos and meiotic segregation patterns analysis of embryos providing from X-autosome translocation carriers.

RESULT(S)

Controlled ovarian stimulation facilitated retrieval of a correct number of oocytes. One balanced embryo per patient was transferred and one developed, but the patient miscarried after 6 weeks of amenorrhea. In X-autosome translocation carriers, balanced Y-bearing embryos are most often phenotypically normal and viable. An ambiguous phenotype exists in balanced X-bearing embryos owing to the X inactivation mechanism. In 46,XX embryos issued from an alternate segregation, der(X) may be inactivated and partially spread transcriptional silencing into a translocated autosomal segment. Thus, the structural unbalanced genotype could be turned into a viable functional balanced one. It is relevant that a discontinuous silencing is observed with a partial and unpredictable inactivation of autosomal regions. Consequently, the resulting phenotype remains a mystery and is considered to be at risk of being an abnormal phenotype in the field of PGD.

CONCLUSION(S)

It is necessary to be cautious regarding to PGD management for this type of translocation, particularly in transferred female embryos.

Technical Update: Preimplantation Genetic Diagnosis and Screening

OBJECTIVE

To update and review the techniques and indications of preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS).

OPTIONS

Discussion about the genetic and technical aspects of preimplantation reproductive techniques, particularly those using new cytogenetic technologies and embryo-stage biopsy.

OUTCOMES

Clinical outcomes of reproductive techniques following the use of PGD and PGS are included. This update does not discuss in detail the adverse outcomes that have been recorded in association with assisted reproductive technologies.

EVIDENCE

Published literature was retrieved through searches of The Cochrane Library and Medline in April 2014 using appropriate controlled vocabulary (aneuploidy, blastocyst/physiology, genetic diseases, preimplantation diagnosis/methods, fertilization in vitro) and key words (e.g., preimplantation genetic diagnosis, preimplantation genetic screening, comprehensive chromosome screening, aCGH, SNP microarray, qPCR, and embryo selection). Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies published from 1990 to April 2014. There were no language restrictions. Searches were updated on a regular basis and incorporated in the update to January 2015. Additional publications were identified from the bibliographies of retrieved articles. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. (Table 1) BENEFITS, HARMS, AND COSTS: This update will educate readers about new preimplantation genetic concepts, directions, and technologies. The major harms and costs identified are those of assisted reproductive technologies.

SUMMARY

Preimplantation genetic diagnosis is an alternative to prenatal diagnosis for the detection of genetic disorders in couples at risk of transmitting a genetic condition to their offspring. Preimplantation genetic screening is being proposed to improve the effectiveness of in vitro fertilization by screening for embryonic aneuploidy. Though FISH-based PGS showed adverse effects on IVF success, emerging evidence from new studies using comprehensive chromosome screening technology appears promising. Recommendations 1. Before preimplantation genetic diagnosis is performed, genetic counselling must be provided by a certified genetic counsellor to ensure that patients fully understand the risk of having an affected child, the impact of the disease on an affected child, and the benefits and limitations of all available options for preimplantation and prenatal diagnosis. (III-A) 2. Couples should be informed that preimplantation genetic diagnosis can reduce the risk of conceiving a child with a genetic abnormality carried by one or both parents if that abnormality can be identified with tests performed on a single cell or on multiple trophectoderm cells. (II-2B) 3. Invasive prenatal or postnatal testing to confirm the results of preimplantation genetic diagnosis is encouraged because the methods used for preimplantation genetic diagnosis have technical limitations that include the possibility of a false result. (II-2B) 4. Trophectoderm biopsy has no measurable impact on embryo development, as opposed to blastomere biopsy. Therefore, whenever possible, trophectoderm biopsy should be the method of choice in embryo biopsy and should be performed by experienced hands. (I-B) 5. Preimplantation genetic diagnosis of single-gene disorders should ideally be performed with multiplex polymerase chain reaction coupled with trophectoderm biopsy whenever available. (II-2B) 6. The use of comprehensive chromosome screening technology coupled with trophectoderm biopsy in preimplantation genetic diagnosis in couples carrying chromosomal translocations is recommended because it is associated with favourable clinical outcomes. (II-2B) 7. Before preimplantation genetic screening is performed, thorough education and counselling must be provided by a certified genetic counsellor to ensure that patients fully understand the limitations of the technique, the risk of error, and the ongoing debate on whether preimplantation genetic screening is necessary to improve live birth rates with in vitro fertilization. (III-A) 8. Preimplantation genetic screening using fluorescence in situ hybridization technology on day-3 embryo biopsy is associated with decreased live birth rates and therefore should not be performed with in vitro fertilization. (I-E) 9. Preimplantation genetic screening using comprehensive chromosome screening technology on blastocyst biopsy, increases implantation rates and improves embryo selection in IVF cycles in patients with a good prognosis. (I-B).

Preimplantation Genetic Diagnosis and Natural Conception: A Comparison of Live Birth Rates in Patients with Recurrent Pregnancy Loss Associated with Translocation

BACKGROUND

Established causes of recurrent pregnancy loss (RPL) include antiphospholipid syndrome, uterine anomalies, parental chromosomal abnormalities, particularly translocations, and abnormal embryonic karyotypes. The number of centers performing preimplantation genetic diagnosis (PGD) for patients with translocations has steadily increased worldwide. The live birth rate with PGD was reported to be 27-54%. The live birth rate with natural conception was reported to be 37-63% on the first trial and 65-83% cumulatively. To date, however, there has been no cohort study comparing age and the number of previous miscarriages in matched patients undergoing or not undergoing PGD. Thus, we compared the live birth rate of patients with RPL associated with a translocation undergoing PGD with that of patients who chose natural conception.

METHODS AND FINDINGS

After genetic counseling, 52 patients who desired natural conception and 37 patients who chose PGD were matched for age and number of previous miscarriages and these comprised the subjects of our study. PGD was performed by means of fluorescence in situ hybridization analysis. The live birth rates on the first PGD trial and the first natural pregnancy after ascertainment of the carrier status were 37.8% and 53.8%, respectively (odds ratio 0.52, 95% confidence interval 0.22-1.23). Cumulative live birth rates were 67.6% and 65.4%, respectively, in the groups undergoing and not undergoing PGD. The time required to become pregnancy was similar in both groups. PGD was found to reduce the miscarriage rate significantly. The prevalence of twin pregnancies was significantly higher in the PGD group. The cost of PGD was $7,956 U.S. per patient.

CONCLUSIONS

While PGD significantly prevented further miscarriages, there was no difference in the live birth rate. Couples should be fully informed of the similarity in the live birth rate, the similarity in time to become pregnancy, the advantages of PGD, such as the reduction in the miscarriage rate, as well as its disadvantages, such as the higher cost, and the advantages of a natural pregnancy, such as the avoidance of IVF failure. The findings presented here should be incorporated into the genetic counseling of patients with RPL and carrying a translocation.