Improved clinical utility of preimplantation genetic testing through the integration of ploidy and common pathogenic microdeletions analyses

STUDY QUESTION

Can chromosomal abnormalities beyond copy-number aneuploidies (i.e. ploidy level and microdeletions (MDs)) be detected using a preimplantation genetic testing (PGT) platform?

SUMMARY ANSWER

The proposed integrated approach accurately assesses ploidy level and the most common pathogenic microdeletions causative of genomic disorders, expanding the clinical utility of PGT.

WHAT IS KNOWN ALREADY

Standard methodologies employed in preimplantation genetic testing for aneuploidy (PGT-A) identify chromosomal aneuploidies but cannot determine ploidy level nor the presence of recurrent pathogenic MDs responsible for genomic disorders. Transferring embryos carrying these abnormalities can result in miscarriage, molar pregnancy, and intellectual disabilities and developmental delay in offspring. The development of a testing strategy that integrates their assessment can resolve current limitations and add valuable information regarding the genetic constitution of embryos, which is not evaluated in PGT providing new level of clinical utility and valuable knowledge for further understanding of the genomic causes of implantation failure and early pregnancy loss. To the best of our knowledge, MDs have never been studied in preimplantation human embryos up to date.

STUDY DESIGN, SIZE, DURATION

This is a retrospective cohort analysis including blastocyst biopsies collected between February 2018 and November 2021 at multiple collaborating IVF clinics from prospective parents of European ancestry below the age of 45, using autologous gametes and undergoing ICSI for all oocytes. Ploidy level determination was validated using 164 embryonic samples of known ploidy status (147 diploids, 9 triploids, and 8 haploids). Detection of nine common MD syndromes (-4p=Wolf-Hirschhorn, -8q=Langer-Giedion, -1p=1p36 deletion, -22q=DiGeorge, -5p=Cri-du-Chat, -15q=Prader-Willi/Angelman, -11q=Jacobsen, -17p=Smith-Magenis) was developed and tested using 28 positive controls and 97 negative controls. Later, the methodology was blindly applied in the analysis of: (i) 100 two pronuclei (2PN)-derived blastocysts that were previously defined as uniformly euploid by standard PGT-A; (ii) 99 euploid embryos whose transfer resulted in pregnancy loss.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The methodology is based on targeted next-generation sequencing of selected polymorphisms across the genome and enriched within critical regions of included MD syndromes. Sequencing data (i.e. allelic frequencies) were analyzed by a probabilistic model which estimated the likelihood of ploidy level and MD presence, accounting for both sequencing noise and population genetics patterns (i.e. linkage disequilibrium, LD, correlations) observed in 2504 whole-genome sequencing data from the 1000 Genome Project database. Analysis of phased parental haplotypes obtained by single-nucleotide polymorphism (SNP)-array genotyping was performed to confirm the presence of MD.

MAIN RESULTS AND THE ROLE OF CHANCE

In the analytical validation phase, this strategy showed extremely high accuracy both in ploidy classification (100%, CI: 98.1-100%) and in the identification of six out of eight MDs (99.2%, CI: 98.5-99.8%). To improve MD detection based on loss of heterozygosity (LOH), common haploblocks were analyzed based on haplotype frequency and LOH occurrence in a reference population, thus developing two further mathematical models. As a result, chr1p36 and chr4p16.3 regions were excluded from MD identification due to their poor reliability, whilst a clinical workflow which incorporated parental DNA information was developed to enhance the identification of MDs. During the clinical application phase, one case of triploidy was detected among 2PN-derived blastocysts (i) and one pathogenic MD (-22q11.21) was retrospectively identified among the biopsy specimens of transferred embryos that resulted in miscarriage (ii). For the latter case, family-based analysis revealed the same MD in different sibling embryos (n = 2/5) from non-carrier parents, suggesting the presence of germline mosaicism in the female partner. When embryos are selected for transfer based on their genetic constitution, this strategy can identify embryos with ploidy abnormalities and/or MDs beyond aneuploidies, with an estimated incidence of 1.5% (n = 3/202, 95% CI: 0.5-4.5%) among euploid embryos.

LIMITATIONS, REASONS FOR CAUTION

Epidemiological studies will be required to accurately assess the incidence of ploidy alterations and MDs in preimplantation embryos and particularly in euploid miscarriages. Despite the high accuracy of the assay developed, the use of parental DNA to support diagnostic calling can further increase the precision of the assay.

WIDER IMPLICATIONS OF THE FINDINGS

This novel assay significantly expands the clinical utility of PGT-A by integrating the most common pathogenic MDs (both de novo and inherited ones) responsible for genomic disorders, which are usually evaluated at a later stage through invasive prenatal testing. From a basic research standpoint, this approach will help to elucidate fundamental biological and clinical questions related to the genetics of implantation failure and pregnancy loss of otherwise euploid embryos.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. S.C., M.F., F.C., P.Z., I.P., L.G., C.P., M.P., D.B., J.J.-A., D.B.-J., J.M.-V., and C.R. are employees of Igenomix and C.S. is the head of the scientific board of Igenomix. A.C. and L.P. are employees of JUNO GENETICS. Igenomix and JUNO GENETICS are companies providing reproductive genetic services.

TRIAL REGISTRATION NUMBER

N/A.

O-285 Artificial intelligence algorithms reach expert-level accuracy in automated grading of blastocyst morphology assessment based on static embryo images and Gardner criteria

Study question

Can artificial intelligence (AI) algorithms reach expert-level accuracy in blastocyst morphology assessment according to Gardner criteria?

Summary answer

The prediction accuracy of the best performing AI algorithm (Deit), outperformed human-level mean accuracies compared to an embryologist majority vote for all Gardner morphological criteria.

What is known already

Routinely, morphological grading of blastocysts is performed visually according to Gardner criteria, which suggest expansion (EXP), quality of inner cell mass (ICM), and trophectoderm (TE) as key parameters to predict treatment outcome. Consequently, blastocyst scoring is prone to inter-and intra-observer variability, which may lead to inconsistencies in selecting blastocysts for transfer. AI-based algorithms may help to improve treatment outcome predictability, as it has been suggested recently. In those studies, parameters such as blastocyst quality or stage were annotated by experts from static or time-lapse-derived blastocyst images, to train AI algorithms, e.g. XCeption or YOLO, and compare them to human annotators.

Study design, size, duration

This retrospective study involves 2,270 images from 837 patients collected over a period of four years in a university IVF clinic.

Participants/materials, setting, methods

All images were annotated by one senior embryologist and divided into a training and a balanced test set. Subsequently, eight embryologists labeled 300 test set images such that every single image was seen by at least four embryologists. Annotators diverging from the ensemble vote for more than one standard deviation were excluded (n = 2) to set the ground truth labels. Finally, three AI architectures (XCeption, Swin, Deit) were trained and evaluated on that particular ground truth.

Main results and the role of chance

Out of nine annotators, labelling accuracy of two embryologists diverged from the consensus vote for more than one standard deviation for at least one of the three Gardner criteria. The consensus vote was built from the remaining seven annotators (mean accuracy EXP 0.81, ICM 0.70, TE 0.67). The Swin architecture outperformed the mean expert accuracy for all three criteria (EXP 0.82, ICM 0.76, TE 0.68), while the Deit and the XCeption architecture outperformed the mean expert accuracy in ICM accuracy (Deit 0.72, XCeption 0.73), and performed equal or worse in EXP and TE accuracy (Deit EXP 0.77, ICM 0.73; XCeption EXP 0.77, TE 0.66). When compared to a recent study conducted on time-lapse imaging data using AI algorithms, all our models outperform the ICM accuracy and achieve comparable TE accuracy. To minimize the role of chance in calculating the models' prediction accuracies, the SWA-Gaussian (SWAG) algorithm was used. SWAG is a method to reflect and calibrate uncertainty representation in Bayesian deep learning. It is based on modelling a Gaussian distribution for each networks' weight and applying it as a posterior over all neural network weights to perform Bayesian model averaging.

Limitations, reasons for caution

To reflect a real IVF lab scenario, embryologists of different origins and levels of experience were involved and no scoring training was offered to the participants. These facts could have potentially negatively affected the degree of consensus, although we excluded two annotators diverging from the mean labeling accuracy.

Wider implications of the findings

In the past, AI algorithms proved to reliably differentiate between good and bad prognosis blastocysts but not necessarily between blastocysts of similar quality. Further AI-supported differentiation on the basis of expansion and cell lineages will facilitate the ranking of blastocysts and would bring automated scoring closer to clinical application.

Trial registration number

Not applicable.

P–530 The use of wide thresholds for detecting intermediate chromosomal CNV up to 80% doesn’t improve PGT-A ability to discriminate true mosaic from uniformly aneuploid embryos

Study question

What is the effect of varying diagnostic thresholds on the accuracy of Next Generation Sequencing (NGS)-based preimplantation genetic testing for aneuploidies (PGT-A)?

Summary answer

When single trophectoderm biopsies are tested, the employment of 80% upper threshold increases mosaic calls and false negative aneuploidy results compared to more stringent thresholds.

What is known already

Trophectoderm (TE) biopsy coupled with NGS-based PGT-A technologies are able to accurately predict Inner Cell Mass’ (ICM) constitution when uniform whole chromosome aneuploidies are considered. However, minor technical and biological inconsistencies in NGS procedures and biopsy specimens can result in subtle variability in analytical results. In this context, the stringency of thresholds employed for diagnostic calls can lead to incorrect classification of uniformly aneuploid embryos into the mosaic category, ultimately affecting PGT-A accuracy. In this study, we evaluated the diagnostic predictivity of different aneuploidy classification criteria by employing blinded analysis of chromosome copy number values (CNV) in multifocal blastocyst biopsies.

Study design, size, duration

The accuracy of different aneuploidy diagnostic cut-offs was assessed comparing chromosomal CNV in intra-blastocysts multifocal biopsies. Enrolled embryos were donated for research between June and September 2020. The Institutional Review Board at the Near East University approved the study (project: YDU/20l9/70–849). Embryos diagnosed with uniform chromosomal alterations (single or multiple) in their clinical TE biopsy (n = 27) were disaggregated into 5 portions: the ICM and 4 TE biopsies. Overall, 135 specimens were collected and analysed.

Participants/materials, setting, methods

Twenty-seven donated blastocysts were warmed and disaggregated in TE biopsies and ICM (n = 135 biopsies). PGT-A analysis was performed using Ion ReproSeq PGS kit and Ion S5 sequencer (ThermoFisher). Sequencing data were blindly analysed with Ion-Reporter software. Intra-blastocyst comparison of raw NGS data was performed employing different thresholds commonly used for aneuploidy classification. CNV for each chromosome were reported as aneuploid according to 70% or 80% thresholds. Categorical variables were compared using Fisher’s exact test.

Main results and the role of chance

In this study, a total of 50 aneuploid patterns in 27 disaggregated embryos were explored. Single TE biopsy results were considered as true positive when they displayed the same alteration detected in the ICM at levels above the 70% or 80% thresholds. Alternatively, alterations detected in the euploid or mosaic range were considered as false negative aneuploidy results. When the 70% threshold was applied, aneuploidy findings were confirmed in 94.5% of TE biopsies analyzed (n = 189/200; 95%CI=90.37–37.22), while 5.5% showed a mosaic profile (50–70%) but uniformly abnormal ICM. Positive (PPV) and negative predictive value (NPV) per chromosome were 100.0% (n = 189/189; 95%CI=98.07–100.00) and 99.5% (n = 2192/2203; 95%CI=99.11–99.75) respectively. When the upper cut-off was experimentally placed at 80% of abnormal cells, a significant decrease (p-value=0.0097) in the percentage of confirmed aneuploid calls was observed (86.5%; n = 173/200; 95%CI=80.97–90.91), resulting in mosaicism overcalling, especially in the high range (50–80%). Less stringent thresholds led to extremely high PPV (100.0%; n = 173/173; 95%CI=97.89–100.00), while NPV decreased to 98.8% (n = 2192/2219; 95%CI=98.30–99.23). Furthermore, no additional true mosaic patterns were identified with the use of wide range thresholds for aneuploidy classification.

Limitations, reasons for caution

This approach involved the analysis of aneuploidy CNV thresholds at the embryo level and lacked from genotyping-based confirmation analysis. Moreover, aneuploid embryos with known meiotic partial deletion/duplication were not included.

Wider implications of the findings: The use of wide thresholds for detecting intermediate chromosomal CNV up to 80% doesn’t improve PGT-A ability to discriminate true mosaic from uniformly aneuploid embryos, lowering overall diagnostic accuracy. Hence, a proportion of the embryos diagnosed as mosaic using wide calling thresholds may actually be uniformly aneuploid and inadvertently transferred.

Trial registration number

N/A

P–273 Effects of ovulation induction with GnRH Agonist (GnRHa) on oocyte and embryo quality at the mitochondrial level: A retrospective and experimental study

Study question

Does the GnRHa trigger improve oocyte and embryo quality in patients younger than 40, and do mtUPPR have a role?

Summary answer

GnRHa trigger improves oocyte nuclear/cytoplasmic maturation, blastocyst utilization and downregulates HSP60 levels and upregulates ATF5 levels compared to hCG trigger. GnRHa trigger suppresses mitochondrial stress.

What is known already

hCG has been used for decades to achieve final oocyte maturation and, thereby, correct oocyte retrieval timing in connection with ovarian hyperstimulation protocols. As an alternative to hCG, a GnRH agonist has been used to trigger the endogenous release of LH (and FSH) in a fashion resembling the mid-cycle surge of gonadotrophins. GnRHa is as effective as hCG for the induction of ovulation. It has been very well known that the GnRHa trigger improves oocyte nuclear maturation, embryo quality, and implantation rate, but the underlying mechanism remains unknown.

Study design, size, duration

3054 women younger than 40; oocytes retrieved more than 10 (up to 20) analyzed. Male infertility was excluded. Ovulation triggered either by hCG (n = 1368) or GnRHa (1668). Female mice were divided into three groups as control, hCG-treated and GnRHa-treated group. Superovulation was performed by FSH + hCG or GnRHa. Oocytes were collected 13 hours after hCG/GnRHa injection. ATF5, BiP, and HSP60 levels were analyzed by Western blot. Statistical analysis was performed using Student’s t-test.

Participants/materials, setting, methods

This study has two parts. i) RCT and ii) Experimental. In the experimental part, three months old female BALB/C mice (25–30 g) were used and divided into three groups (n = 20/group) as control, hCG-treated and GnRHa-treated group. Superovulation was performed by administering an injection of 5 IU FSH (i.p.) and hCG (i.p.) or GnRHa (20 mg/kg) i.m. Oocytes were collected 13 hours after hCG/GnRHa injection. ATF5, BiP, and HSP60 levels were analyzed by Western blot.

Main results and the role of chance

The mean age (34.8 vs. 35.2 years), total gonadotropin dose (2176 vs. 2230 IU), and the number of oocytes picked up (14.9 vs. 13.4) were not statistically different among GnRHa and hCG group, respectively. No LH rise or any OHSS was noticed in any groups.

Oocyte maturation (79.8% vs. 75.9%), oocyte diameter (as a marker of cytoplasmic maturity) (10198 µm2 and 9474 µm2), fertilization rate (78% vs. 72%), and embryo utilization rate (52% vs. 47.2%) were significantly higher in GnRHa group compared to hCG group, respectively.

HSP60 level (activated by mtUPR) was statistically higher in the hCG group compared to the GnRHa group (55% vs. 22%, p < 0.05 respectively). On the other hand, the ATF5 level was significantly higher in the GnRHa group than the hCG group (p < 0.0001).

Limitations, reasons for caution

The limitation is that this is a proof-of-concept study to reveal the mechanism of good embryo quality with GnRHa trigger.

Wider implications of the findings: This application offers convenience and simplifies the IVF protocol with a better oocyte and embryo quality while reducing Ovarian Hyperstimulation Syndrome (OHSS) risk during IVF care

Trial registration number

Not applicable

Preliminary FISH studies on spermatozoa and embryos in patients with variable degrees of teratozoospermia and a history of poor prognosis

The aim of this study was to analyse to what extent sperm aneuploidy is associated with sperm morphology and subsequently with embryo aneuploidy. Fifty-nine men with variable degrees of teratozoospermia and previously poor assisted reproduction prognosis were included in the study. Samples from 10 normozoospermic men with proven fertility were used as controls. Individual spermatozoa were scored for chromosomes 13, 21 and for 18, X, Y separately. Compared with controls, 23 out of 59 cases (39.0%) were found to have increased sperm aneuploidy for at least one of the chromosomes analysed in a treatment cycle. Fifty-two patients underwent a treatment cycle and were documented according to the pregnancy and spermatozoa fluorescence in-situ hybridization results. A total of 121 previous unsuccessful assisted reproduction cycles of the cases were then retrospectively reviewed. In 23 of the latest cycles, preimplantation genetic diagnosis was applied to 106 cleavage stage embryos and 47 of 94 embryos analysed (50.0%) were found to be chromosomally abnormal. Furthermore, 16 of 47 (34.0%) embryos with chromosomal abnormality were carrying complex chromosomal defects. The results imply that increased aneuploidy is present in both spermatozoa and embryos in couples with severe male infertility with a history of repeated unsuccessful attempts. Therefore, proper genetic counselling should be considered in these cases.

Human embryonic stem cell culture: current limitations and novel strategies

Embryonic stem cells (ESC) are multipotent cells isolated from blastocyst-stage preimplantation embryos. Since their first culture in 1998, human ESC have revolutionized reproductive and regenerative medicine by allowing the establishment of detailed molecular and therapeutic models for certain metabolic pathways and life-threatening disorders. They also offer significant contributions to genetics and pharmacology in designing and analysing disease models that can be closer to in vivo than any other procedures available. However, the procedures by which they are obtained and manipulated also create intense ethical and social debates worldwide. This article discusses the current limitations and recent advances in isolation, culture and differentiation of human ESC from the laboratory perspective.

Embryo aneuploidy screening for repeated implantation failure and unexplained recurrent miscarriage

Among other factors, chromosomal abnormalities that originate from gametogenesis and preimplantation embryonic development are thought to be one of the major contributing factors for early embryonic death and failure of pregnancy. However, so far, no non-invasive technique exists that allows the detection of the chromosomal complement of an oocyte or a developing embryo as a whole. Rather, by removing polar bodies/blastomeres, recent developments on preimplantation genetic diagnosis for aneuploidy screening (PGD-AS) have paved the way to detect and possibly eliminate the majority of chromosomally abnormal embryos, thereby increasing the chance of a healthy pregnancy. This article summarizes the origin and impact of chromosomal abnormalities on human reproduction in cases with repeated implantation failure (RIF) and unexplained recurrent miscarriage. It also discusses recent advances regarding the possible benefits of PGD-AS in such cases.

Clinical aspects of preimplantation genetic diagnosis for single gene disorders combined with HLA typing

Preimplantation genetic diagnosis (PGD) for single gene disorders combined with human leukocyte antigen (HLA) matching has recently emerged as a therapeutic tool for stem cell transplantation in couples bearing an affected offspring. There may exist, however, several patient- or cycle-specific limitations for certain couples. This article documents data regarding experience of single gene disorders combined with HLA matching obtained at Istanbul Memorial Hospital, Turkey. The data were obtained from 20 couples undergoing 26 PGD-HLA cycles for thalassaemia (n = 23), Wiscott-Aldrich syndrome (n = 1) and acute lymphoblastic leukaemia (n = 2). A total of 206 embryos was biopsied on day 3 of embryo development and subsequently analysed. After the analysis, 26 (12.6%) of them were found to be both healthy and HLA compatible. In 16 embryo transfers performed, seven (43.7%) clinical pregnancies were obtained, one of which resulted in miscarriage. Ten of the 26 cycles started (38.4%) were cancelled due to a lack of suitable (mutation-free and/or HLA-compatible) embryos. The data suggest that application of PGD in combination with HLA typing is a promising therapeutic tool for an affected sibling.

The results of aneuploidy screening in 276 couples undergoing assisted reproductive techniques

Preimplantation genetic diagnosis for aneuploidy screening (PGD-AS) using sequential in situ hybridization was applied for aneuploidy testing in 276 couples with 282 ART cycles. Patients with advanced maternal age (AMA, n = 147), recurrent implantation failure (RIF, n = 48), repeated early spontaneous abortion (RSA, n = 32) and abnormal gamete cell morphology (AGCM, n = 55) including macrocephal sperm forms or cytoplasmic granular oocytes were included. Embryo biopsy was performed on day 3 in a calcium-magnesium-free medium by using a noncontact diode laser system. After fixation and enzymatic treatment, fluorescent in situ hybridization (FISH) was carried out on 1147 blastomeres with specific probes for chromosomes 13, 16, 18, 21 and 22 for AMA group, 13, 18, 21, X and Y for AGCM group and 13, 16, 18, 21, 22, X and Y for RIF and RSA groups respectively. The overall chromosomal abnormality rate in analyzed embryos was 40.9%, with no significant difference between AMA, RIF and RSA groups (p > 0.05). However, AGCM group presented a higher rate of chromosomal aneuploidies (57.4%) than the other three groups (p < 0.01). A total of 84% biopsied embryos presented cleavage in 24 h and embryo transfer was realized in 278 cycles. In four cycles, no chromosomally normal embryo was found for embryo transfer. A total of 88 pregnancies (31.6%) were achieved, 19.3% resulted in abortion and 63 healthy births were obtained, with a total of 93 babies born. Aneuploidy testing in couples with poor prognosis undergoing ART cycles is a useful tool to increase the chance of ART success. Furthermore, abnormal gamete cell morphology should be considered one of the major indications for PGD in ART programs as high aneuploidy rates were observed in this group.

Assessment of DNA fragmentation and aneuploidy on poor quality human embryos

In human assisted reproduction, low embryo quality due to retarded growth and abnormal cellular morphology results in fewer embryos suitable for transfer. This study aimed to assess the extent of DNA fragmentation and aneuploidy in spare slow growing or arrested human embryos. In 19 assisted reproduction cycles, a total of 57 embryos unsuitable for embryo transfer were used for simultaneous apoptosis and aneuploidy assessment. Among them, 31 (54.3%) showed DNA fragmentation by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) analysis. Among 26 embryos that were negative for TUNEL, interpretable fluorescence in-situ hybridization (FISH) results were obtained for 25 embryos (96.2%). Sixteen embryos were detected to be chromosomally abnormal (64.0%); three were found to be chaotic, six had complex aneuploidy, six had complete monosomy and one was polyploid. The results show that a high level of DNA fragmentation and aneuploidy are common in embryos with slow growth and/or low quality. More detailed studies are needed to assess the effect of factors such as ovarian stimulation regimens and in-vitro culture conditions. Moreover, application of simultaneous TUNEL and FISH techniques can be informative regarding DNA integrity and aneuploidy.

Effect of PGD on implantation and ongoing pregnancy rates in cases with predominantly macrocephalic spermatozoa

Although its occurrence is rare, the presence of large headed or macrocephalic spermatozoa and increased chromosomal abnormality has recently been reported by several groups. Moreover, when intracytoplasmic sperm injection (ICSI) was performed with samples containing macrocephalic spermatozoa, lower fertilization and implantation rates result in poor clinical outcome. In order to evaluate the impact of preimplantation genetic diagnosis (PGD) on implantation and ongoing pregnancy rates in these couples, the results of 23 PGD cycles were compared with non-PGD cycles (n = 60) as well as cycles with absolute teratozoospermia (having zero normal morphology) with (n = 14) or without PGD (n = 66). Out of 82 embryos biopsied in the macrocephalic sperm group, abnormalities were detected in 46.4% of the embryos analysed. Most of the abnormalities were trisomies (37.0%) and complex aneuploidies (51.9%). A 33.3% pregnancy rate was achieved by selectively transferring euploid embryos after PGD with the statistically higher implantation rate of 25.0% compared with non-PGD cycles (IR: 12.3%, P < 0.01). Moreover, only one missed abortion (14.3%) was observed in the PGD group, whereas seven of the 15 pregnancies resulted in abortion in the non-PGD group (46.7%). Preliminary results indicate that patients should be counselled for increased chromosomal abnormality and a possible beneficial effect of eliminating chromosomally abnormal embryos with PGD on a bortion rates.

Results of preimplantation genetic diagnosis in patients with Klinefelter's syndrome

With the application of preimplantation genetic diagnosis (PGD), a possible genetic contribution of spermatozoa obtained from 47,XXY non-mosaic Klinefelter patients on preimplantation embryos was analysed in eight couples. Interpretable fluorescence in-situ hybridization results were obtained for 28 out of 33 embryos biopsied (84.8%) and 23 blastomeres were analysed for chromosomes 13, 18, 21, X and Y. Nine out of 23 embryos were diagnosed as abnormal (39.1%). Five out of nine contained sex chromosome abnormalities (55.5%). Two were diagnosed as 47,XXY and three were found to have monosomy X. Besides sex chromosomal abnormalities, other abnormalities detected were haploidy, triploidy, monosomy 13, monosomy 18 and trisomy 13. Five blastomeres were analysed for sex chromosomes only and all of them were found to be normal. Overall, the rate of sex chromosome abnormality in biopsied embryos was found to be 17.8% (5/28). Moreover, among 33 embryos biopsied, five of the eight zygotes, which were classified as a poor prognosis group according to pronuclear morphology scoring, showed an impaired growth profile after biopsy and were found to be chromosomally abnormal. Elimination of abnormal embyos and transfer of normal ones resulted in four pregnancies in eight cycles (50%). Two pregnancies, one singleton and one twins resulted in healthy births. Two pregnancies, one singleton and one twins are continuing beyond the second trimester. These results show that there is in fact elevated chromosomal abnormality for both sex chromosomes and autosomes in embryos developed from Klinefelter males. Furthermore together with PGD, embryo scoring according to pronuclear morphology can give additional benefit for selecting chromosomally abnormal embryos. Therefore, PGD should be recommended in cases with Klinefelter's syndrome and this information should be discussed with the couple when genetic counselling is given.

Embryo development characteristics in Robertsonian and reciprocal translocations: a comparison of results with non-translocation cases

The effect of translocations on embryo development was evaluated and results were compared in terms of embryo development with those of embryos obtained from standard intracytoplasmic sperm injection (ICSI) cycles. In 23 translocation carriers with 34 cycles, fertilization, pronuclear morphology scoring (PMS), developmental arrest, cleavage and blastocyst formation were evaluated and compared with embryos obtained from non-translocation cases undergoing ICSI (n = 98 cycles). In 28 cycles, preimplantation genetic diagnosis (PGD) was performed on prezygotes (first and second polar body biopsy for female carriers; n = 3) or on embryos having seven or more blastomeres (blastomere biopsy; n = 25). In six cycles for four couples, probes for translocated chromosomes were not available, so PGD could not be performed. Overall, in translocation cases, a lower fertilization rate, a higher rate of retarded embryo development, and a lower rate of blastocyst formation were observed compared with embryos of non-translocation cases. Fluorescence in-situ hybridization (FISH) analysis showed a 70.9% abnormality rate for reciprocal translocations and 55.0% for Robertsonian translocations respectively. In cases with Robertsonian and reciprocal translocation carriers, the probability of poor embryo development, which may be a result of high segregation abnormalities, may negatively affect the outcome of assisted reproductive techniques. This poor prognosis should also be considered when genetic counselling for translocation is given.

Pronuclear morphology scoring and chromosomal status of embryos in severe male infertility

BACKGROUND

The study aim was to evaluate the relationship between pronuclei morphology scoring (PNMS) and the chromosomal complement of embryos in couples with severe male infertility undergoing ICSI. A total of 3116 pre-embryos was scored according to PNMS in 452 cycles.

METHODS

Pre-embryos were classified into eight categories based on the alignment, size, linear or irregular distribution of pronuclear bodies (PNB), position and clarity of cytoplasmic halo and abutting of the pronucleus. These categories were subdivided into groups I and II according to the similarity and distribution of PNB.

RESULTS

In total, 2574 pre-embryos formed by using ejaculated sperm, while 542 pre-embryos developed by injection of testicular sperm or round spermatids. More group II pre-embryos with markedly different morphology from group I were formed after ICSI with testicular sperm than with fresh ejaculated sperm (32.1 versus 22.7%, P < 0.01). Of 490 pre-embryos in which pronuclear morphology was evaluated, 263 were biopsied for preimplantation genetic diagnosis. The rate of chromosomal abnormality was higher in embryos developed from group II pre-embryos (52.2%) than in embryos developed from group I prezygotes (37.6%, P < 0.05).

CONCLUSIONS

Group II pre-embryos had markedly different morphology from group I, and had a low rate of blastocyst formation and high risk of chromosomally abnormal embryos. When testicular sperm and round spermatids were used for ICSI, more group II pre-embryos and chromosomally abnormal embryos were produced than with ejaculated sperm. Pronuclear morphology was correlated with chromosomal complement, and impacted upon by the sperm source.

Acquired expression of transcriptionally active p73 in hepatocellular carcinoma cells

p53 and p73 proteins activate similar target genes and induce apoptosis and cell cycle arrest. However, p53, but not p73 is considered a tumour-suppressor gene. Unlike p53, p73 deficiency in mice does not lead to a cancer-prone phenotype, and p73 gene is not mutated in human cancers, including hepatocellular carcinoma. Here we report that normal liver cells express only DeltaN-p73 transcript forms giving rise to the synthesis of N-terminally truncated, transcriptionally inactive and dominant negative p73 proteins. In contrast, most hepatocellular carcinoma cells express TA-p73 transcript forms encoding full-length and transcriptionally active p73 proteins, in addition to DeltaN-p73. We also show that together with the acquired expression of TA-p73, the 'retinoblastoma pathway' is inactivated, and E2F1-target genes including cyclin E and p14(ARF) are activated in hepatocellular carcinoma. However, there was no full correlation between 'retinoblastoma pathway' inactivation and TA-p73 expression. Most TA-p73-expressing hepatocellular carcinoma cells have also lost p53 function either by lack of expression or missense mutations. The p73 gene, encoding only DeltaN-p73 protein, may function as a tumour promoter rather than a tumour suppressor in liver tissue. This may be one reason why p73 is not a mutation target in hepatocellular carcinoma.