The effect of polymorphisms in FSHR gene on late follicular phase progesterone and estradiol serum levels in predicted normoresponders

STUDY QUESTION

Does the presence of FSHR single-nucleotide polymorphisms (SNPs) affect late follicular phase progesterone and estradiol serum levels in predicted normoresponders treated with rFSH?

SUMMARY ANSWER

The presence of FSHR SNPs (rs6165, rs6166, rs1394205) had no clinically significant impact on late follicular phase serum progesterone and estradiol levels in predicted normoresponders undergoing a GnRH antagonist protocol with a fixed daily dose of 150 IU rFSH.

WHAT IS KNOWN ALREADY

Previous studies have shown that late follicular phase serum progesterone and estradiol levels are significantly correlated with the magnitude of ovarian response. Several authors have proposed that individual variability in the response to ovarian stimulation (OS) could be explained by variants in FSHR. However, so far, the literature is scarce on the influence of this genetic variability on late follicular phase steroidogenic response. Our aim is to determine whether genetic variants in the FSHR gene could modulate late follicular phase serum progesterone and estradiol levels.

STUDY DESIGN, SIZE, DURATION

In this multicenter multinational prospective study conducted from November 2016 to June 2019, 366 patients from Vietnam, Belgium and Spain (166 from Europe and 200 from Asia) underwent OS followed by oocyte retrieval in a GnRH antagonist protocol with a fixed daily dose of 150 IU rFSH. All patients were genotyped for 3 FSHR SNPs (rs6165, rs6166, rs1394205) and had a serum progesterone and estradiol measurement on the day of trigger.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Included patients were predicted normal responder women <38 years old undergoing their first or second OS cycle. The prevalence of late follicular phase progesterone elevation (PE), as well as mean serum progesterone and estradiol levels on the day of trigger were compared between the different FSHR SNPs genotypes. PE was defined as >1.50 ng/ml.

MAIN RESULTS AND THE ROLE OF CHANCE

The overall prevalence of PE was 15.8% (n = 58). No significant difference was found in the prevalence of PE in Caucasian and Asian patients (17.5% versus 14.5%). Estradiol levels on the day of trigger and the number of retrieved oocytes were significantly higher in patients with PE (4779 ± 6236.2 versus 3261 ± 3974.5 pg/ml, P = 0.003, and 16.1 ± 8.02 versus 13.5 ± 6.66, P = 0.011, respectively). Genetic model analysis, adjusted for patient age, body mass index, number of retrieved oocytes and continent (Asia versus Europe), revealed a similar prevalence of PE in co-dominant, dominant and recessive models for variants FSHR rs6166, rs6165 and rs1394205. No statistically significant difference was observed in the mean late follicular phase progesterone serum levels according to the genotypes of FSHR rs6166 (P = 0.941), rs6165 (P = 0.637) and rs1394205 (P = 0.114) in the bivariate analysis. Also, no difference was found in the genetic model analysis regarding mean late follicular phase progesterone levels across the different genotypes. Genetic model analysis has also revealed no statistically significant difference regarding mean estradiol levels on the day of trigger in co-dominant, dominant and recessive models for variants FSHR rs6166, rs6165 and rs1394205. Haplotype analysis revealed a statistically significant lower estradiol level on the day of trigger for rs6166/rs6165 haplotypes GA, AA and GG when compared to AG (respectively, estimated mean difference (EMD) -441.46 pg/ml (95% CI -442.47; -440.45), EMD -673.46 pg/ml (95% CI -674.26; -672.67) and EMD -582.10 pg/ml (95% CI -584.92; -579.28)). No statistically significant differences were found regarding the prevalence of PE nor late follicular phase progesterone levels according to rs6166/rs6165 haplotypes.

LIMITATIONS, REASONS FOR CAUTION

Results refer to a population of predicted normal responders treated with a normal/low fixed dose of 150 IU rFSH throughout the whole OS. Consequently, caution is needed before generalizing our results to all patient categories.

WIDER IMPLICATIONS OF THE FINDINGS

Based on our results, FSHR SNPs rs6165, rs6166 and rs1394205 do not have any clinically significant impact neither on late follicular phase serum progesterone nor on estradiol levels in predicted normal responders. These findings add to the controversy in the literature regarding the impact of individual genetic susceptibility in response to OS in this population.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by an unrestricted grant by Merck Sharp & Dohme (MSD, IISP56222). N.P.P. reports grants and/or personal fees from MSD, Merck Serono, Roche Diagnostics, Ferring International, Besins Healthcare, Gedeon Richter, Organon, Theramex and Institut Biochimique SA (IBSA). C.A. reports conference fees from Merck Serono, Medea and Event Planet. A.R.N., C.B., C.S., P.Q.M.M., H.T., C.B., N.L.V., M.T.H. and S.G. report no conflict of interests related to the content of this article.

TRIAL REGISTRATION NUMBER

NCT03007043.

P-660 Polymorphisms in FSHR gene do not affect late follicular phase steroidogenic response in predicted normoresponders. Secondary analysis of a prospective multicenter cohort study

Study question

Does the presence of FSHR SNPs influence late follicular phase progesterone and estradiol serum levels in predicted normoresponders treated with rFSH?

Summary answer

The presence of FSHR SNPs (rs6165, rs6166, rs1394205) had no statistically significant impact on late follicular phase serum progesterone and estradiol levels.

What is known already

Previous studies have shown that late follicular phase serum progesterone and estradiol levels are significantly correlated with the magnitude of ovarian response. Several authors have proposed that individual variability in the response to ovarian stimulation could be explained by variants in FSHR. So far, the literature is scarce on the influence of this genetic variability on late follicular phase steroidogenic response. Our aim is to determine whether genetic variants in the FSHR gene could modulate late follicular phase serum progesterone and estradiol levels.

Study design, size, duration

We performed a secondary analysis of a multicenter multinational prospective study including 366 patients from Vietnam, Belgium and Spain (166 from Europe and 200 from Asia), conducted from 11/2016-06/2019. All patients underwent ovarian stimulation followed by oocyte retrieval in an antagonist protocol with a fixed daily dose of 150IU rFSH. All patients had a serum progesterone and estradiol measurement on the day of trigger and were genotyped for 3 FSHR SNPs (rs6165, rs6166, rs1394205).

Participants/materials, setting, methods

Patients included were predicted normal responder women &lt;38 years old undergoing their first or second ovarian stimulation cycle. The prevalence of late follicular phase elevated serum progesterone (EP), as well as mean serum progesterone and estradiol levels on the day of trigger were compared between the different FSHR SNPs genotypes. EP was defined as &gt; 1.5 ng/ml.

Main results and the role of chance

The overall prevalence of EP was 15.8% (n = 58). No significant difference was found in the prevalence of EP in Caucasian and Asian patients (17.5% vs. 14.5%). Genetic model analysis revealed a similar prevalence of EP in co-dominant, dominant and recessive models for variants FSHR rs6166, rs6165 and rs1394205. Also, no statistically significant difference was found in the mean serum progesterone levels in the three genetic models. Likewise, FSHR SNPs genotypes had no statistically significant impact in the mean late follicular phase serum estradiol levels

Limitations, reasons for caution

This study is a post-hoc analysis of a multicenter multinational prospective cohort study. The results must be interpreted with caution considering the sample size of the EP group. The fact that a fixed daily dose of 150 IU rFSH was used in this population precludes the generalization of the results.

Wider implications of the findings

Based on our results, FSHR SNPs rs6165, rs6166, rs1394205 do not influence late follicular phase serum progesterone nor estradiol levels in predicted normal responders. These findings add to the controversy in the literature regarding the impact of individual genetic susceptibility in response to ovarian stimulation in this population.

Trial registration number

not-applicable

P-662 Association between polymorphisms in FSHR and reproductive outcomes following IVF. Secondary analysis of a prospective cohort study in Europe and Asia

Study question

Does the presence of FSHR variants influence the clinical pregnancy rate (CPR), live birth rate (LBR) and cumulative live birth rate (CLBR) in predicted normoresponders?

Summary answer

The presence of at least one G allele in FSHR variant rs6165 is associated with higher CPR and LBR when compared to genotype AA.

What is known already

FSHR protein expression has been found in the placenta, umbilical cord, amnion and decidua, suggesting a role in the promotion of a healthy pregnancy. Previous reports have analysed the impact of FSHR SNP rs6166 in pregnancy outcomes with conflicting results, mainly due to the heterogeneity in the inclusion criteria and limited sample size. Moreover, the literature is scarce regarding the association between FSHR SNPs rs6165 and rs1394205 and reproductive outcomes. Our aim is to determine whether FSHR SNPs rs6166, rs6166 and rs1394205 influence the reproductive prognosis following IVF.

Study design, size, duration

We performed a secondary analysis of a multicenter multinational prospective study, including 368 patients from Vietnam, Belgium and Spain (168 from Europe and 200 from Asia) from 11/2016-06/2019. All patients underwent ovarian stimulation with fixed-dose 150IU rFSH in an antagonist protocol.

Participants/materials, setting, methods

Patients aged &lt;38 years, undergoing their first or second IVF cycle with a predicted normal response (antral follicle count &gt;9 and/or antimullerian hormone &gt;1.1ng/ml) were included. CPR, LBR and miscarriage rate (MR) in the first embryo transfer, as well as CLBR, were compared between the different genotypes of FSHR SNPs rs6166, rs6165 and rs1394205.

Main results and the role of chance

A total of 351 patients performed at least one embryo transfer (ET). Enrolled patients had a mean age of 30.5 ± 3.63 years. Mean CPR and LBR in the first ET were 56.1% and 48.4%, respectively. Univariate genetic model analysis revealed a significantly higher CPR in the dominant model for variant rs6165 (46.3% (38/82) for genotype AA vs 59.1% (159/269) for genotypes AG/GG, p = 0.04). No statistically significant difference was found regarding the CPR for variants rs6166 nor rs1394205. Also, no statistically significant difference was found in univariate analysis regarding LBR nor MR for the different FSHR variants. However, multivariable logistic regression analysis adjusted for patient age, BMI, ethnicity, type of embryo transfer, embryo stage and number of top quality embryos transferred revealed a statistically significant higher CPR and LBR for FSHR variant rs6165 genotype GG (adjOR 2.50, 95% CI 1.30-4.81, and adjOR 1.96, 95%CI 1.02-3.78, respectively). No statistically significant differences were found regarding CLBR for FSHR variants rs6166, rs6165 nor rs1394205.

Limitations, reasons for caution

The young age of the included patients precludes the generalization of the results to older patients. Also, the results should be confirmed in larger cohorts before being extrapolated to the general population.

Wider implications of the findings

Our results demonstrate a previously unreported association between variant FSHR SNPs rs6165 genotype GG and higher CPR and LBR and reinforce a potential role for the genetic background in the prediction of a favorable prognosis following IVF.

Trial registration number

not-applicable

O-042 ESHRE good practice recommendations on chromosomal mosaicism

The implementation of high-resolution genome-wide methods, usually next-generation sequencing-based, in preimplantation genetic testing (PGT), has led to the frequent detection of embryos with chromosomal mosaicism (whole chromosome and/or segmental aberrations). Despite a growing series of papers showing the birth of healthy babies following the transfer of embryos indicating mosaicism on PGT-A analysis - albeit with lower implantation rates and higher miscarriage rates in comparison with euploid embryo transfer - many questions remain, making it difficult to decide on how to handle chromosomally mosaic embryos in the clinic.

A dedicated ESHRE working group developed good practice recommendations on how to manage chromosomal mosaicism in clinical practice. The recommendations were formulated based on the expert opinion of the working group while taking into consideration the published data and outcomes of a survey on current practices in 239 PGT laboratories and ART clinics, mostly within Europe, Asia and America. The recommendations with regards to detection and management of chromosomal mosaicism were developed following the manual for development of ESHRE good practice recommendations with a stakeholder review of the paper on the ESHRE website. In addition to the recommendations, the working group identified missing information and scientific questions, which should guide further research in PGT, with relevance to the occurrence, detection and impact of chromosomal mosaicism.

Trial registration number:

O-184 Maternally inherited differences in mitochondrial DNA genotype between ART and spontaneously conceived individuals associate with low birthweight

Study question

Can mitochondrial DNA (mtDNA) variants explain the differences in birthweight between ART and spontaneously conceived (SC) individuals and how do they originate?

Summary answer

Children born after ART carry more frequently a different mtDNA variant composition, both maternally inherited and de novo, which are predictive of their birthweight percentile.

What is known already

Children born after ART show an increased risk of lower birthweight and of developing a mild abnormal cardio-metabolic profile later in life. Variation in the mtDNA associates with overall health in the general population, including cardio-metabolic fitness, and can result in changes in mitochondrial function. We hypothesized that mitochondrial DNA variants could explain the differences in birthweight between ART and SC individuals and that these differences may result from maternal transmission and/or from the ovarian stimulation (OS) used in ART.

Study design, size, duration

We deep-sequenced the mtDNA of 472 individuals of who 283 ART and 189 SC, 182 mother-child pairs and 113 single oocytes from both natural menstrual cycles and OS cycles. The mtDNA was compared between groups and Fisher linear discriminant analysis was used as predictive model for the birthweight percentile.

Participants/materials, setting, methods

Mitochondrial DNA was enriched by long-range PCR and subsequently sequenced on an Illumina platform. mtDNA server and MuTect were used for variant calling for variants with a load higher than 1.5%, versus the reference NC_012920.1. An orthogonally rotated factor analysis was used to reduce the dimensionality of the studied dependent variables in the complex data of the heteroplasmic variants.

Main results and the role of chance

ART individuals carried more frequently haplogroup U4 (p = 0.004) and component analysis indicated that they carry a different mtDNA heteroplasmic variant composition than SC individuals (p = 0.01), driven by non-synonymous protein-coding and rRNA-coding variants. These differences were also predictive of the risk of a lower birthweight percentile, especially for the SC children, together with the absence of haplogroup T, the presence of homoplasmic tRNA-variants, pregnancy-induced hypertension and the embryo culture medium used. The differences in heteroplasmic variation observed in the ART children resulted from both maternal transmission (p = 0.03) and de novo mutagenesis (p = 0.02). Mothers of ART children showed a similar mtDNA genotype as their children and differed in the same variant composition when compared to the mothers of SC children (p = 0.03). Furthermore, the comparison of oocytes from the same donors retrieved in natural menstrual cycles and after one OS cycle showed that OS does not increase de novo mutagenesis. Additionally, clinical parameters such as the total dosage of FSH units, the number of oocytes retrieved, and maternal age did not show any correlation with the differences observed in ART individuals.

Limitations, reasons for caution

This study is observational with no functional tests being performed.

Wider implications of the findings

We demonstrate an association between a lower birthweight percentile and a mtDNA variant composition which is more frequently carried by ART children. These non-disease associated mtDNA variants could cause a suboptimal mitochondrial function affecting the birthweight. Long-term health consequences of these differences remain to be further elucidated.

Trial registration number

Not applicable

O-205 Aneuploidy induces proteotoxic stress and autophagy-mediated apoptosis in human preimplantation embryos

Study question

Are aneuploid cells in human preimplantation embryos eliminated by apoptosis due to proteotoxic stress and autophagy-mediated apoptosis?

Summary answer

Proteotoxic stress, autophagy and apoptosis are differentially activated in aneuploid embryos, showing that aneuploid cells are eliminated by these mechanisms during early human embryogenesis.

What is known already

Aneuploidies are a common feature of human preimplantation embryos which could explain low success rates after in vitro fertilization (IVF). While most aneuploidies of meiotic origin are detrimental, transfer of euploid-aneuploid mosaic embryos can lead to healthy live-births. Moreover, the proportion of aneuploid cells are lower in blastocysts when compared to cleavage stage embryos. In the mouse, aneuploid cells are eliminated from the epiblast by autophagy-mediated apoptosis in a p53-dependent manner. We propose that in human embryos, aneuploidy causes chronic protein misfolding which leads to autophagy-induced apoptosis.

Study design, size, duration

Eighty-one blastocysts that were diagnosed by PGT as euploid (n = 49) or uniformly combined abnormal (CA, n = 32), i.e. 2 or more chromosomes were abnormal in every cell, were warmed. Sixty-seven were suitable for trophectoderm (TE) biopsy, 54 biopsies were successfully tubed and sent for RNA-sequencing while the remainder of the embryos was fixed for immunostaining. Thirty-three day-3 embryos were overnight incubated in 0.5µM reversine allowed to develop into blastocysts and treated as the PGT embryos.

Participants/materials, setting, methods

After TE biopsy, we live-stained the embryos with either Caspase-3/7 or 8 and subsequently fixed them. The biopsies underwent RNA-sequencing using the SMART-seqv4 and the fixed embryos were immunostained for LC3B, p62 (autophagy) and HSP70 (proteotoxic stress). Confocal imaging was performed using a Zeiss LSM800 confocal microscope and the presence of signal was quantified using the Zen Blue 2.0 and Arivis software.

Main results and the role of chance

Forty-two percent of the embryos in which we induced aneuploidies using reversine developed into blastocysts, which is comparable to untreated embryos. After immunostaining, we observed that CA and reversine-treated (RT) embryos contained less cells than euploid embryos (median number of nuclei: 43.5, 47, 90, respectively). This correlates with a higher expression of apoptotic markers Caspase-3/7 in CA embryos (p = 0.0199) and Caspase-8 in both aneuploid groups (CA: p = 0.0085 and RT: p = 0.0394). Aneuploid embryos showed significantly increased HSP70 levels (median intensity per cell: euploid=165, CA = 313, RT = 400), LC3B (median puncta per cell: euploid=3.07, CA = 10.10, RT = 19.62) and p62 (median puncta per cell: euploid=17.60, CA = 30.53), suggesting increased proteotoxic stress and autophagy. Preliminary analysis of the RNA-sequencing data reveals enrichment for pathways such as the p53-pathway, protein secretion, TNFA signaling via NFkB and apoptosis, supporting the hypothesis of a link between aneuploidy and apoptosis.

Limitations, reasons for caution

No functional tests e.g. with inhibitors of autophagy were carried out. RNA-sequencing was carried out on a small sample; we will expand this sample in the near future.

Wider implications of the findings

This study shows for the first time the mechanism by which aneuploid cells are eliminated from the human preimplantation embryo, explaining how mosaic embryos can still lead to a healthy and genetically normal live birth.

Trial registration number

not applicable

The effect of polymorphisms in FSHR and FSHB genes on ovarian response: a prospective multicenter multinational study in Europe and Asia

STUDY QUESTION

Does the presence of single nucleotide polymorphisms (SNPs) in the FSH receptor gene (FSHR) and/or FSH beta subunit-encoding gene (FSHB) influence ovarian response in predicted normal responders treated with rFSH?

SUMMARY ANSWER

The presence of FSHR SNPs (rs6165, rs6166, rs1394205) has a statistically significant impact in ovarian response, although this effect is of minimal clinical relevance in predicted normal responders treated with a fixed dose of 150 IU rFSH.

WHAT IS KNOWN ALREADY

Ovarian reserve markers have been a breakthrough in response prediction following ovarian stimulation. However, a significant percentage of patients show a disproportionate lower ovarian response, as compared with their actual ovarian reserve. Studies on pharmacogenetics have demonstrated a relationship between FSHR or FSHB genotyping and drug response, suggesting a potential effect of individual genetic variability on ovarian stimulation. However, evidence from these studies is inconsistent, due to the inclusion of patients with variable ovarian reserve, use of different starting gonadotropin doses, and allowance for dose adjustments during treatment. This highlights the necessity of a well-controlled prospective study in a homogenous population treated with the same fixed protocol.

STUDY DESIGN, SIZE, DURATION

We conducted a multicenter multinational prospective study, including 368 patients from Vietnam, Belgium, and Spain (168 from Europe and 200 from Asia), from November 2016 until June 2019. All patients underwent ovarian stimulation followed by oocyte retrieval in an antagonist protocol with a fixed daily dose of 150 IU rFSH until triggering. Blood sampling and DNA extraction was performed prior to oocyte retrieval, followed by genotyping of four SNPs from FSHR (rs6165, rs6166, rs1394205) and FSHB (rs10835638).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Eligible were predicted normal responder women <38 years old undergoing their first or second ovarian stimulation cycle. Laboratory staff and clinicians were blinded to the clinical results and genotyping, respectively. The prevalence of hypo-responders, the number of oocytes retrieved, the follicular output rate (FORT), and the follicle to oocyte index (FOI) were compared between different FSHR and FSHB SNPs genotypes.

MAIN RESULTS AND THE ROLE OF CHANCE

The prevalence of derived allele homozygous SNPs in the FSHR was rs6166 (genotype G/G) 15.8%, rs6165 (genotype G/G) 34.8%, and rs1394205 (genotype A/A) 14.1%, with significant differences between Caucasian and Asian women (P < 0.001). FSHB variant rs10835638 (c.-211 G>T) was very rare (0.5%). Genetic model analysis revealed that the presence of the G allele in FSHR variant rs6166 resulted in less oocytes retrieved when compared to the AA genotype (13.54 ± 0.46 vs 14.81 ± 0.61, estimated mean difference (EMD) -1.47 (95% CI -2.82 to -0.11)). In FSHR variant rs1394205, a significantly lower number of oocytes was retrieved in patients with an A allele when compared to G/G (13.33 ± 0.41 vs 15.06 ± 0.68, EMD -1.69 (95% CI -3.06 to -0.31)). A significantly higher prevalence of hypo-responders was found in patients with the genotype A/G for FSHR variant rs6166 (55.9%, n = 57) when compared to A/A (28.4%, n = 29), ORadj 1.87 (95% CI 1.08-3.24). No significant differences were found regarding the FORT across the genotypes for FSHR variants rs6166, rs6165, or rs1394205. Regarding the FOI, the presence of the G allele for FSHR variant rs6166 resulted in a lower FOI when compared to the A/A genotype, EMD -13.47 (95% CI -22.69 to -4.24). Regarding FSHR variant rs6165, a lower FOI was reported for genotype A/G (79.75 ± 3.35) when compared to genotype A/A (92.08 ± 6.23), EMD -13.81 (95% CI -25.41 to -2.21).

LIMITATIONS, REASONS FOR CAUTION

The study was performed in relatively young women with normal ovarian reserve to eliminate biases related to age-related fertility decline; thus, caution is needed when extrapolating results to older populations. In addition, no analysis was performed for FSHB variant rs10835638 due to the very low prevalence of the genotype T/T (n = 2).

WIDER IMPLICATIONS OF THE FINDINGS

Based on our results, genotyping FSHR SNPs rs6165, rs6166, rs1394205, and FSHB SNP rs10835638 prior to initiating an ovarian stimulation with rFSH in predicted normal responders should not be recommended, taking into account the minimal clinical impact of such information in this population. Future research may focus on other populations and other genes related to folliculogenesis or steroidogenesis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by an unrestricted grant by Merck Sharp & Dohme (MSD). N.P.P. reports grants and/or personal fees from MSD, Merck Serono, Roche Diagnostics, Ferring International, Besins Healthcare, Gedeon Richter, Theramex, and Institut Biochimique SA (IBSA). N.L.V. and M.T.H. report consultancy and conference fees from Merck, Ferring, and MSD, outside the submitted work. P.D. has received honoraria for lecturing and/or research grants from MSD, Ferring International, and Merck. D.S. reports grants and/or personal fees from MSD, Ferring International, Merck Serono, Cook, and Gedeon Richter. A.R.N., B.A.M., C.S., J.M., L.H.L., P.Q.M.M., H.T., and S.G. report no conflict of interests.

TRIAL REGISTRATION NUMBER

NCT03007043.

Expression of adhesion and extracellular matrix genes in human blastocysts upon attachment in a 2D co-culture system

STUDY QUESTION

What are the changes in human embryos, in terms of morphology and gene expression, upon attachment to endometrial epithelial cells?

SUMMARY ANSWER

Apposition and adhesion of human blastocysts to endometrial epithelial cells are predominantly initiated at the embryonic pole and these steps are associated with changes in expression of adhesion and extracellular matrix (ECM) genes in the embryo.

WHAT IS KNOWN ALREADY

Both human and murine embryos have been co-cultured with Ishikawa cells, although embryonic gene expression associated with attachment has not yet been investigated in an in vitro implantation model.

STUDY DESIGN, SIZE, DURATION

Vitrified human blastocysts were warmed and co-cultured for up to 48 h with Ishikawa cells, a model cell line for receptive endometrial epithelium.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Six days post-fertilization (6dpf) human embryos were co-cultured with Ishikawa cells for 12, 24 (7dpf) or 48 h (8dpf) and attachment rate and morphological development investigated. Expression of 84 adhesion and ECM genes was analysed by quantitative PCR. Immunofluorescence microscopy was used to assess the expression of three informative genes at the protein level. Data are reported on 145 human embryos. Mann-Whitney U was used for statistical analysis between two groups, with P < 0.05 considered significant.

MAIN RESULTS AND THE ROLE OF CHANCE

The majority of embryos attached to Ishikawa cells at the level of the polar trophectoderm; 41% of co-cultured embryos were loosely attached after 12 h and 86% firmly attached after 24 h. Outgrowth of hCG-positive embryonic cells at 8dpf indicated differentiation of trophectoderm into invasive syncytiotrophoblast. Gene expression analysis was performed on loosely attached and unattached embryos co-cultured with Ishikawa cells for 12 h. In contrast to unattached embryos, loosely attached embryos expressed THBS1, TNC, COL12A1, CTNND2, ITGA3, ITGAV and LAMA3 and had significantly higher CD44 and TIMP1 transcript levels (P = 0.014 and P = 0.029, respectively). LAMA3, THBS1 and TNC expressions were validated at the protein level in firmly attached 7dpf embryos. Thrombospondin 1 (THBS1) resided in the cytoplasm of embryonic cells whereas laminin subunit alpha 3 (LAMA3) and tenascin C (TNC) were expressed on the cell surface of trophectoderm cells. Incubation with a neutralizing TNC antibody did not affect the rate of embryo attachment or hCG secretion.

LARGE SCALE DATA

None.

LIMITATIONS, REASONS FOR CAUTION

This in vitro study made use of an endometrial adenocarcinoma cell line to mimic receptive luminal epithelium. Also, the number of embryos was limited. Contamination of recovered embryos with Ishikawa cells was unlikely based on their differential gene expression profiles.

WIDER IMPLICATIONS OF THE FINDINGS

Taken together, we provide a 'proof of concept' that initiation of the implantation process coincides with the induction of specific embryonic genes. Genome-wide expression profiling of a larger sample set may provide insights into the molecular embryonic pathways underlying successful or failed implantation.

STUDY FUNDING AND COMPETING INTEREST(S)

A.A. was supported by a grant from the 'Instituut voor Innovatie door Wetenschap en Technologie' (IWT, 121716, Flanders, Belgium). This work was supported by the 'Wetenschappelijk Fonds Willy Gepts' (WFWG G142 and G170, Universitair Ziekenhuis Brussel). The authors declare no conflict of interest.

Gain of 20q11.21 in Human Pluripotent Stem Cells Impairs TGF-β-Dependent Neuroectodermal Commitment

Gain of 20q11.21 is one of the most common recurrent genomic aberrations in human pluripotent stem cells. Although it is known that overexpression of the antiapoptotic gene Bcl-xL confers a survival advantage to the abnormal cells, their differentiation capacity has not been fully investigated. RNA sequencing of mutant and control hESC lines, and a line transgenically overexpressing Bcl-xL, shows that overexpression of Bcl-xL is sufficient to cause most transcriptional changes induced by the gain of 20q11.21. Moreover, the differentially expressed genes in mutant and Bcl-xL overexpressing lines are enriched for genes involved in TGF-β- and SMAD-mediated signaling, and neuron differentiation. Finally, we show that this altered signaling has a dramatic negative effect on neuroectodermal differentiation, while the cells maintain their ability to differentiate to mesendoderm derivatives. These findings stress the importance of thorough genetic testing of the lines before their use in research or the clinic.

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Bcl-xL overexpression drives the transcriptomic profile of 20q11.21 mutant lines

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20q11.21 mutant lines downregulate CHCHD2, a known TGF-β pathway modulator

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Mutant lines differentially express genes involved in TGF-β and SMAD signaling

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Mutant lines show impaired ectoderm commitment due to TGF-β signaling deregulation

Recent developments in genetics and medically assisted reproduction: from research to clinical applications

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Recent developments in genetics and medically-assisted reproduction: from research to clinical applications†‡

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively-parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Chromosome constitution of human embryos generated after in vitro maturation including 3-isobutyl-1-methylxanthine in the oocyte collection medium

STUDY QUESTION

Do cleavage-stage embryos obtained from oocytes matured in vitro after pre-incubation with a phosphodiesterase inhibitor (IBMX) carry more chromosomal abnormalities than those generated from oocytes matured in vivo?

SUMMARY ANSWER

The rate and type of chromosomal abnormalities in normally developing cleavage-stage embryos generated with an in vitro maturation (IVM) system including pre-incubation with IBMX are not different from those observed in supernumerary embryos obtained from oocytes matured in vivo.

WHAT IS KNOWN ALREADY

Very limited information is available about the chromosomal constitution of IVM embryos. Previous studies were carried out using FISH on single biopsied blastomeres or arrested whole embryos and only provided fragmentary information on chromosomal abnormalities in IVM embryos. There is no systematic study of chromosomal abnormalities in all blastomeres of human Day 3 embryos with good morphology.

STUDY DESIGN, SIZE, DURATION

Between July 2012 and December 2012, 16 young (age <35 years old) egg donors underwent 18 IVM cycles for the generation of research embryos. Eighteen embryos developed to Day 3 and were analysed using array comparative genomic hybridization (aCGH).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Immature oocytes were retrieved from 2 to 10 mm follicles after mild ovarian stimulation with gonadotrophins but without hCG ovulation trigger. At collection, oocytes were pre-incubated with 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor and matured in vitro. After IVM culture, mature oocytes were microinjected with sperm from a single donor. Embryos were cultured to Day 3 after ICSI and all blastomeres of 18 good-morphology embryos were collected individually for aCGH.

MAIN RESULTS AND THE ROLE OF CHANCE

Oocyte maturation rate in vitro was 50.2% (120/239). The mean fertilization rate was 68.3% (82/120) and 30.5% (25/82) of fertilized oocytes developed into a morphologically good quality embryo on Day 3 after ICSI. Of these, 18 embryos that developed well up to Day 3 were analysed using aCGH. Eighty of the 123 blastomeres analysed showed at least one chromosomal abnormality. Three out of eighteen embryos had completely normal cells. A single embryo carried a meiotic abnormality, 11 embryos were mosaic and three were chaotic. Although the aneuploidy data of this study are too limited to allow statistical analysis, these data are comparable to our own published data on the chromosome constitution of whole day 3 and day 4 embryos after conventional ART.

LIMITATIONS, REASONS FOR CAUTION

Array CGH technology determines relative quantification of chromosomal domains but does not allow for the visualization of chromosomal rearrangements, assessment of ploidy or detection of uniparental isodisomy. Conclusions drawn on segmental abnormalities should be treated with caution. Although the limited number of embryos analysed here precludes firm conclusions, they provide valuable data on possible causes of the reduced potential of IVM embryos.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study to describe the complete chromosome complement of all single blastomeres of good-morphology day 3 embryos obtained with IVM (including the presence of IBMX in a pre-incubation medium). The results demonstrate that a high proportion of good-morphology embryos are aneuploid and that there is no obvious increase in aneuploidies as a result of IVM which seems to suggest that the reduced efficiency of IVM technology compared with standard IVF may be accounted for by factors other than aneuploidy, such as cytoplasmic defects or reduced endometrial receptivity.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by the TBM (Applied Biomedical Research with Societal Finality) programme of the IWT (Agency for Innovation through Science and Technology - Flanders, 110680) and by a Methusalem grant of the Vrije Universiteit Brussel. C.S. is a post-doctoral fellow of the Fund for Scientific Research Flanders (FWO - Vlaanderen). K.J. is a PhD student funded by the FWO. The University of Adelaide owns a patent family associated with IVM technologies that is licensed to Cook Medical. R.B.G. and J.G.T. are inventors. The remaining authors have no conflict of interest to declare.

Gain of 20q11.21 in human embryonic stem cells improves cell survival by increased expression of Bcl-xL

Gain of 20q11.21 is a chromosomal abnormality that is recurrently found in human pluripotent stem cells and cancers, strongly suggesting that this mutation confers a proliferative or survival advantage to these cells. In this work we studied three human embryonic stem cell (hESC) lines that acquired a gain of 20q11.21 during in vitro culture. The study of the mRNA gene expression levels of the loci located in the common region of duplication showed that HM13, ID1, BCL2L1, KIF3B and the immature form of the micro-RNA miR-1825 were up-regulated in mutant cells. ID1 and BCL2L1 were further studied as potential drivers of the phenotype of hESC with a 20q11.21 gain. We found no increase in the protein levels of ID1, nor the downstream effects expected from over-expression of this gene. On the other hand, hESC with a gain of 20q11.21 had on average a 3-fold increase of Bcl-xL (the anti-apoptotic isoform of BCL2L1) protein levels. The mutant hESC underwent 2- to 3-fold less apoptosis upon loss of cell-to-cell contact and were ∼2-fold more efficient in forming colonies from a single cell. The key role of BCL2L1 in this mutation was further confirmed by transgenic over-expression of BCL2L1 in the wild-type cells, leading to apoptosis-resistant cells, and BCL2L1-knock-down in the mutant hESC, resulting in a restoration of the wild-type phenotype. This resistance to apoptosis supposes a significant advantage for the mutant cells, explaining the high frequency of gains of 20q11.21 in human pluripotent stem cells.

Evolution of aneuploidy up to Day 4 of human preimplantation development

STUDY QUESTION

What is the incidence of aneuploidy and mosaicism in all cells of top-quality Day-4 embryos analysed by array-based comparative genomic hybridization (array CGH)?

SUMMARY ANSWER

Our data show extensive abnormalities in Day-4 embryos.

WHAT IS KNOWN ALREADY

Numerous studies on human embryos at Day 3 and Day 5 of development show that they frequently contain aneuploid cells and are mosaic, although Day-5 embryos contain proportionally more normal cells than at Day 3. In contrast, only limited data exist on Day 4 of preimplantation development, despite the fact that it is the suggested stage for the initiation of the process of self-correction.

STUDY DESIGN, SIZE, DURATION

Thirteen embryos were analysed: four fresh good-quality preimplantation genetic diagnosis (PGD) embryos and nine good-quality surplus embryos cryopreserved on Day 3 and donated for research. On Day 4, following removal of the zona pellucida, all blastomeres were disaggregated and collected.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The genomic DNA of 283 single blastomeres from disaggregated embryos was amplified. Array CGH was carried out using 24SureTM Cytochip microarrays. After scanning of the microarray slides, the images were analysed using BlueFuse Software (BlueGnome). Combined with selective microsatellite analysis, hypothetical reconstructions of embryo chromosome complements were made following each of the first four cleavage divisions.

MAIN RESULTS AND THE ROLE OF CHANCE

No chromosome imbalance was detected for one PGD embryo, the other three were mosaic containing between 16 and 75% abnormal cells. All nine frozen-thawed embryos were abnormal. Six were mosaic with between 30 and 100% abnormal cells; three had abnormalities of meiotic origin, two of which displayed mitotic abnormalities. Evidence was also found of mitotic unbalanced structural chromosome rearrangements. The higher rate of abnormality of frozen-thawed embryos is based on a small number of embryos and cannot be tested statistically. The aneuploidy can mostly be explained by anaphase lag and non-disjunction. In some cases, we hypothesize endoreduplication followed by a cellular division with multipolar spindles to explain the results.

LIMITATIONS, REASONS FOR CAUTION

Array CGH technology determines relative quantification of chromosomal domains but does not allow for the visualization of chromosomal rearrangements, assessment of ploidy or detection of uniparental isodisomy. Conclusions drawn on segmental abnormalities should be treated with caution. The division trees presented are hypothetical models projecting back in time that try to explain observations in single blastomeres of Day 4 embryos. The limited number of embryos analysed does not allow drawing firm conclusions, but nevertheless provides valuable data on the origin of aneuploidy in human embryos.

WIDER IMPLICATIONS OF THE FINDINGS

Our data show extensive abnormalities in Day-4 embryos. We found no evidence of self-correction at this stage of development, suggesting that this process may start at a later stage of development.

Genetic and epigenetic instability in human pluripotent stem cells

BACKGROUND

There is an increasing body of evidence that human pluripotent stem cells (hPSCs) are prone to (epi)genetic instability during in vitro culture. This review aims at giving a comprehensive overview of the current knowledge on culture-induced (epi)genetic alterations in hPSCs and their phenotypic consequences.

METHODS

Combinations of the following key words were applied as search criteria: human induced pluripotent stem cells and human embryonic stem cells in combination with malignancy, tumorigenicity, X inactivation, mitochondrial mutations, genomic integrity, chromosomal abnormalities, culture adaptation, aneuploidy and CD30. Only studies in English, on hPSCs and focused on (epi)genomic integrity were included. Further manuscripts were added from cross-references.

RESULTS

Numerous (epi)genetic aberrations have been detected in hPSCs. Recurrent genetic alterations give a selective advantage in culture to the altered cells leading to overgrowth of abnormal, culture-adapted cells. The functional effects of these alterations are not yet fully understood, but suggest a (pre)malignant transformation of abnormal cells with decreased differentiation and increased proliferative capacity.

CONCLUSIONS

Given the high degree of (epi)genetic alterations reported in the literature and altered phenotypic characteristics of the abnormal cells, controlling for the (epi)genetic integrity of hPSCs before any clinical application is an absolute necessity.

Microarray analysis reveals abnormal chromosomal complements in over 70% of 14 normally developing human embryos

STUDY QUESTION

What are the aneuploidy rates and incidence of mosaicism in good-quality human preimplantation embryos.

SUMMARY ANSWER

High-level mosaicism and structural aberrations are not restricted to arrested or poorly developing embryos but are also common in good-quality IVF embryos.

WHAT IS KNOWN ALREADY

Humans, compared with other mammals, have a poor fertility rate, and even IVF treatments have a relatively low success rate. It is known that human gametes and early preimplantation embryos carry chromosomal abnormalities that are thought to lower their developmental potential.

STUDY DESIGN, SIZE AND DURATION

The embryos studied came from nine young (age <35 years old) IVF patients and were part of a cohort of embryos that all resulted in healthy births. These 14 embryos inseminated by ICSI and cryopreserved on Day 2 of development were thawed, cultured overnight and allowed to succumb by being left at room temperature for 24 h. Following removal of the zona pellucida, blastomeres were disaggregated and collected.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

There were 91 single blastomeres collected and amplified by multiple displacement amplification. Array-comparative genomic hybridization was performed on the amplified DNA. Array-data were normalized and aneuploidy was detected by the circular binary segmentation method.

MAIN RESULTS AND THE ROLE OF CHANCE

The good-quality embryos exhibited high rates of aneuploidy, 10 of 14 (71.4%) of the embryos being mosaic. While none of the embryos had the same aneuploidy pattern in all cells, 4 of 14 (28.6%) were uniformly diploid. Of the 70 analysed blastomeres, 55.7% were diploid and 44.3% had chromosomal abnormalities, while 29% of the abnormal cells carried structural aberrations.

WIDER IMPLICATIONS OF THE FINDINGS

Finding such a high rate of aneuploidy and mosaicism in excellent quality embryos from cycles with a high implantation rate warrants further research on the origin and significance of chromosomal abnormalities in human preimplantation embryos.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by the Instituut voor de aanmoediging van innovatie door Wetenschap en Technologie in Vlaanderen (IWT-Vlaanderen). A.M. is a PhD student at the IWT-Vlaanderen. C.S. is a postdoctoral fellow at the FWO Vlaanderen. There are no competing interests.

Methylation of the CpG sites in the myotonic dystrophy locus does not correlate with CTG expansion size or with the congenital form of the disease

We have studied the methylation status of the sequence 152 nucleotides upstream of the CTG repeat of the DM1 locus in patients' peripheral blood. We used the methylation-sensitive endonucleases SacII, HpaII and HhaI, followed by PCR. This allowed to correlate the methylation status of each CTG allele with its size. Contrary to previous findings, only the SacII site is often but not always differentially methylated among expanded CTG alleles. Importantly, this methylation was not restricted to congenital DM1, nor to large expansions, as it was also present in DM1 patients with a classical phenotype and various expansion sizes. On the other hand, we did not find any methylated alleles on the HhaI and HpaII sites, as was reported by Steinbach et al, which is in line with the results of Shaw and collaborators. The size range of the repeat expansions with methylation was from as small as 300 to as large as 2800 repeats.

Characterization of CD30 expression in human embryonic stem cell lines cultured in serum-free media and passaged mechanically

BACKGROUND

The presence of chromosomal abnormalities could have a negative impact for human embryonic stem cell (hESC) applications both in regenerative medicine and in research. A biomarker that allows the identification of chromosomal abnormalities induced in hESC in culture before they take over the culture would represent an important tool for defining optimal culture conditions for hESC. Here we investigate the expression of CD30, reported to be a biomarker of hESCs with abnormal karyotype, in undifferentiated and spontaneously differentiated hESC.

METHODS AND RESULTS

hESC were derived and cultured on mouse fibroblasts in KO-SR containing medium (serum free media) and passaged mechanically. Our results based on analysis at mRNA (RT-PCR) and protein (fluorescence-activated cell sorting and immunocytochemistry) level show that CD30 is expressed in undifferentiated hESC, even at very early passages, without any correlation with the presence of chromosomal anomalies. We also show that the expression of CD30 is rapidly lost during early spontaneous differentiation of hESC.

CONCLUSION

We conclude that CD30 expression in hESC cultures is probably a consequence of culture conditions, and that KO-SR may play a role. In addition, the expression of so-called 'stemness' markers does not change in undifferentiated hESC during long-term culture or when cells acquire chromosomal abnormalities.

Preimplantation genetic diagnosis for cancer predisposition syndromes

OBJECTIVES

Mutations in the APC, NF2 and BRCA1 genes cause adult-onset cancer predisposition syndromes. Prenatal diagnosis (PND) and selective pregnancy termination for adult-onset disorders is emotionally difficult and, in some cases, socially not well accepted. Preimplantation genetic diagnosis (PGD) appears as an attractive alternative to PND, as it ensures the establishment of a pregnancy free of the mutation from the onset, circumventing the potentially difficult decision of termination of pregnancy.

METHODS

Development of single-cell PCRs using Epstein-Barr virus transformed lymphoblasts as single-cell model, followed by clinical application in PGD.

RESULTS

A total of five duplex-PCRs were developed, three for adenomatous polyposis of the colon (APC), one for neurofibromatosis type 2 (NF2) and one for inherited breast and ovarian cancer caused by BRCA1 mutations. Eleven clinical cycles were performed, resulting in the birth of an unaffected girl. For one of the couples undergoing PGD for NF2, a spontaneous pregnancy ensued after five unsuccessful PGD cycles. The couple underwent chorionic villus sampling (CVS) and the application of the same protocol as used during PGD showed an unaffected fetus.

CONCLUSION

In this work, we present the development and clinical application of PGD for three cancer predisposition syndromes.

Optimization and evaluation of single-cell whole-genome multiple displacement amplification

The scarcity of genomic DNA can be a limiting factor in some fields of genetic research. One of the methods developed to overcome this difficulty is whole genome amplification (WGA). Recently, multiple displacement amplification (MDA) has proved very efficient in the WGA of small DNA samples and pools of cells, the reaction being catalyzed by the phi29 or the Bst DNA polymerases. The aim of the present study was to develop a reliable, efficient, and fast protocol for MDA at the single-cell level. We first compared the efficiency of phi29 and Bst polymerases on DNA samples and single cells. The phi29 polymerase generated accurately, in a short time and from a single cell, sufficient DNA for a large set of tests, whereas the Bst enzyme showed a low efficiency and a high error rate. A single-cell protocol was optimized using the phi29 polymerase and was evaluated on 60 single cells; the DNA obtained DNA was assessed by 22 locus-specific PCRs. This new protocol can be useful for many applications involving minute quantities of starting material, such as forensic DNA analysis, prenatal and preimplantation genetic diagnosis, or cancer research.

Preimplantation genetic diagnosis for neurofibromatosis type 1

PGD is an alternative to prenatal diagnosis that circumvents therapeutic abortion. Diagnosis is carried out on single cells obtained from three-day-old embryos, and only those that are free of the disease under consideration are transferred to the mother. Neurofibromatosis type 1 (NF1) is a common neurocutaneous disorder, inherited as an autosomal dominant trait and caused by mutations in the NF1 gene. For some patients, PGD may be the only acceptable manner to ensure the birth of unaffected children. Because of the large number of known NF1 mutations, the development of mutation-specific single-cell protocols is impractical, labour-intensive and expensive. This paper discusses the development of five PGD protocols, three of which are based on multiplex PCR for microsatellite-markers linked to the NF1 gene. After a linkage study, the diagnosis can be established through the markers, thereby obviating the need to detect the mutation itself. This not only ensures the accurate diagnosis of the embryos, but also a prompt acceptance of PGD referrals since one protocol can be useful for several couples. In addition, two mutation-specific PCRs were developed for two couples where a marker-based protocol was not applicable. In total, 16 PGD cycles were carried out for six couples, which resulted in one ongoing pregnancy and the delivery of a healthy unaffected boy.