Aspects of biopsy procedures prior to preimplantation genetic diagnosis

Obstetric and neonatal outcomes of pregnancies resulting from preimplantation genetic testing: a systematic review and meta-analysis

BACKGROUND

Preimplantation genetic testing (PGT) includes methods that allow embryos to be tested for severe inherited diseases or chromosomal abnormalities. In addition to IVF/ICSI and repeated freezing and thawing of the embryos, PGT requires a biopsy to obtain embryonic genetic material for analysis. However, the potential effects of PGT on obstetric and neonatal outcomes are currently uncertain.

OBJECTIVE AND RATIONALE

This study aimed to investigate whether pregnancies conceived after PGT were associated with a higher risk of adverse obstetric and neonatal outcomes compared with spontaneously conceived (SC) pregnancies or pregnancies conceived after IVF/ICSI.

SEARCH METHODS

PubMed, EMBASE, MEDLINE, Web of Science and The Cochrane Library entries from January 1990 to January 2021 were searched. The primary outcomes in this study were low birth weight (LBW) and congenital malformations (CMs), and the secondary outcomes included gestational age, preterm delivery (PTD), very preterm delivery (VPTD), birth weight (BW), very low birth weight (VLBW), neonatal intensive care unit (NICU) admission, hypertensive disorders of pregnancy (HDP), gestational diabetes, placenta previa and preterm premature rupture of membranes (PROM). We further pooled the results of PGT singleton pregnancies. Subgroup analyses included preimplantation genetic diagnosis (PGD), preimplantation genetic screening (PGS), cleavage-stage biopsy combined with fresh embryo transfer (CB-ET) and blastocyst biopsy combined with frozen-thawed embryo transfer (BB-FET).

OUTCOMES

This meta-analysis included 15 studies involving 3682 babies born from PGT pregnancies, 127 719 babies born from IVF/ICSI pregnancies and 915 222 babies born from SC pregnancies. The relative risk (RR) of LBW was higher in PGT pregnancies compared with SC pregnancies (RR = 3.95, 95% confidence interval [CI]: 2.32-6.72), but the risk of CMs was not different between the two groups. The pooled results for the risks of LBW and CMs were similar in PGT and IVF/ICSI pregnancies. The risks of PTD (RR = 3.12, 95% CI: 2.67-3.64) and HDP (RR = 3.12, 95% CI: 2.18-4.47) were significantly higher in PGT pregnancies compared with SC pregnancies. Lower gestational age (mean difference [MD] = -0.76 weeks, 95% CI -1.17 to -0.34) and BW (MD = -163.80 g, 95% CI: -299.35 to -28.24) were also noted for PGT pregnancies compared with SC pregnancies. Nevertheless, compared with IVF/ICSI pregnancies, the risks of VPTD and VLBW in PGT pregnancies were significantly decreased by 41% and 30%, respectively, although the risk of HDP was still significantly increased by 50% in PGT pregnancies compared with IVF/ICSI pregnancies. The combined results of obstetric and neonatal outcomes of PGT and IVF/ICSI singleton pregnancies were consistent with the overall results. Further subgroup analyses indicated that both PGD and PGS pregnancies were associated with a higher risk of PTD and a lower gestational age compared with SC pregnancies.

WIDER IMPLICATIONS

This meta-analysis showed that PGT pregnancies may be associated with increased risks of LBW, PTD and HDP compared with SC pregnancies. The overall obstetric and neonatal outcomes of PGT pregnancies are favourable compared with those of IVF/ICSI pregnancies, although PGT pregnancies were associated with a higher risk of HDP. However, because the number of studies that could be included was limited, more randomised controlled trials and prospective cohort studies are needed to confirm these conclusions.

Between innovation and precaution: how did offspring safety considerations play a role in strategies of introducing new reproductive techniques?

The field of reproductive medicine has been criticized for introducing ARTs without systematic research on possible safety risks and for failing to meet the standards of evidence-based innovation held elsewhere in medicine. In this paper, firstly, we ask whether ‘responsible innovation’ has been a concern for the field, and if so, how it has understood the practical implications of this idea for the development and introduction of potentially risky new ARTs. Secondly, we consider whether the field has indeed fallen short of its responsibilities in this respect, and if so, how things can be improved. To answer these questions, we present three case studies involving the introduction of a new reproductive technology: ICSI, preimplantation genetic testing and mitochondrial replacement therapy. As a framework for analyzing these cases, we used Per Sandin’s account of the four dimensions of dealing with risks (threat, uncertainty, action, command) that are central to debates about the possible role of the so-called precautionary principle. We conclude that, although offspring safety concerns have been on the agenda of the debate about bringing the relevant technologies to the clinic, systematic safety and effectiveness studies were not always conducted. As professionals in assisted reproduction have a responsibility to take account of the welfare of the children they are creating, we suggest a policy of proceeding with systematic caution. Legal measures may be needed to ensure that professional guidance is followed in practice. Finally, an open question concerns the threshold for acceptable risk in the context of introducing new ARTs. Multiple stakeholders, including professional societies and patient organizations, should have a role in the urgent debate about this.

The relationship between the percent of euploid embryo and the tolerance of embryo biopsy in preimplantation genetic screening: A systematic review and meta-analysis of randomized controlled trials

The aim of this study was to analyze the relationship between the percent of euploid embryo and the tolerance of embryo biopsy in preimplantation genetic screening (PGS).PubMed and trial registers were searched for clinical studies that patients were randomized to the PGS group or the control group from 1995 to October 2017. The patients of advanced maternal age, repeated implantation failure, and good prognosis with or without PGS in randomized controlled trials (RCTs) were collected.Original data from 9 RCT studies comparing in-vitro fertilization with and without PGS including 1642 patients were obtained and they were divided into 3 subgroups according to the percent of euploid embryo. PGS significantly increased live birth babies per embryo transferred (risk ratio: 2.98, 95% confidence interval: 1.54-5.75) in ≤30% of euploid embryo subgroups and but in other 2 groups, PGS has no effect. Significant negative correlation was found between the percent of euploid embryo and the tolerance of embryo biopsy in PGS (r = 0.80, P = 0.010)The tolerance of embryo biopsy in PGS was associated negatively with the percent of euploid embryo. There was a beneficial effect when PGS was used in the patients with the lowest percent of euploid embryo.

Does blastomere removal alter the expression level of miR-Let7a and its target genes following mouse embryo biopsy?

Embryo manipulations may cause the misexpression of various genes, most of which play critical roles in the regulation of implantation. This study aimed to evaluate the effects of embryo biopsy on the expression of miR-Let-7a and its gene targets including ErbB4, Tgf-α, Itg-αv, Itg β3 on the implantation of mouse embryo. Embryos were produced by in vitro fertilization followed by blastomere biopsy at the eight-cell stage. The effects of blastomere removal on the expression of genes ErbB4, Tgf-α, Itg αv, Itg β3, and miR-Let-7a as well as the alteration of the blastocyst cell number were compared in both biopsied and non-biopsied groups. Finally, blastocyst attachment was assessed on culture dishes precoated with Fibronectin. The results revealed that there were no significant differences between the biopsied and non-biopsied embryos with reference to the blastocyst formation rates, the average inner cell mass, trophectoderm cell number, and percentage of attachment of blastocysts (P > 0.05). The expression of ErbB4, Itg-β3, Itg-αv, TGF-α transcripts, and miR-Let-7a in blastocysts biopsied embryos did not differ from the non-biopsied blastocysts (P > 0.05). The results demonstrated that the preimplantation embryo development and attachment of biopsied embryos in vitro is not adversely affected by one blastomere biopsy at the eight-cell stage embryo.

Implementing PGD/PGD-A in IVF clinics: considerations for the best laboratory approach and management

For an IVF clinic that wishes to implement preimplantation genetic diagnosis for monogenic diseases (PGD) and for aneuploidy testing (PGD-A), a global improvement is required through all the steps of an IVF treatment and patient care. At present, CCS (Comprehensive Chromosome Screening)-based trophectoderm (TE) biopsy has been demonstrated as a safe, accurate and reproducible approach to conduct PGD-A and possibly also PGD from the same biopsy. Key challenges in PGD/PGD-A implementation cover genetic and reproductive counselling, selection of the most efficient approach for blastocyst biopsy as well as of the best performing molecular technique to conduct CCS and monogenic disease analysis. Three different approaches for TE biopsy can be compared. However, among them, the application of TE biopsy approaches, entailing the zona opening when the expanded blastocyst stage is reached, represent the only biopsy methods suited with a totally undisturbed embryo culture strategy (time lapse-based incubation in a single media). Moreover, contemporary CCS technologies show a different spectrum of capabilities and limits that potentially impact the clinical outcomes, the management and the applicability of the PGD-A itself. In general, CCS approaches that avoid the use of whole genome amplification (WGA) can provide higher reliability of results with lower costs and turnaround time of analysis. The future perspectives are focused on the scrupulous and rigorous clinical validations of novel CCS methods based on targeted approaches that avoid the use of WGA, such as targeted next-generation sequencing technology, to further improve the throughput of analysis and the overall cost-effectiveness of PGD/PGD-A.

Probability of finding at least one euploid embryo and the euploidy rate according to the number of retrieved oocytes and female age using FISH and array CGH

Objective:

To assess the probability of finding at least one euploid embryo (POE) and euploidy rate in preimplantation genetic screening (PGS) cycles for aneuploidy testing with fluorescent in situ hybridization (FISH) and array comparative genomic hybridization (aCGH) based on the number of retrieved oocytes after adjustment for age.

Design:

Retrospective data analysis.

Setting:

Private in vitro fertilization center in a general hospital, Istanbul, Turkey.

Patient(s):

In this study, 1412 couples with 1739 cycles were included.

Intervention(s):

Embryo biopsy at cleavage stage or trophectoderm biopsy analyzed by FISH or aCGH techniques.

Main outcome measure(s):

Probability of finding at least one euploid embryo for transfer and euploidy rate according to retrieved oocytes after adjustment for age.

Result(s):

Estimated probabilities of finding at least one euploid embryo were plotted based on age and number of retrieved oocytes. When controlled for age, the POE increased with each additional oocyte retrieved (OR 1.11, 95% CI 1.08–1.14), but the euploidy rate did not. When retrieved oocytes were subgrouped, we found that the odds of finding at least one euploidy embryo were highest when 16–20 oocytes were retrieved compared to 1–5 oocytes with both FISH (OR 8.62, 95% CI 4.67–15.93) and aCGH (OR 2.78, 95% CI 1.07–7.21). However, the chances did not increase with the retrieval of more than 20 oocytes.

Conclusion(s):

The estimated probabilities of finding at least one transferrable embryo would enable more accurate counselling of patients based on age and the number of retrieved oocytes. As the highest estimates for finding one euploidy embryo were achieved with 15-20 oocytes, deciding the best protocol for ovarian stimulation to achieve the maximum number of oocytes for retrieval based on the patients age and ovarian reserve would be of crucial importance.

The why, the how and the when of PGS 2.0: current practices and expert opinions of fertility specialists, molecular biologists, and embryologists

STUDY QUESTION

We wanted to probe the opinions and current practices on preimplantation genetic screening (PGS), and more specifically on PGS in its newest form: PGS 2.0?

STUDY FINDING

Consensus is lacking on which patient groups, if any at all, can benefit from PGS 2.0 and, a fortiori, whether all IVF patients should be offered PGS.

WHAT IS KNOWN ALREADY

It is clear from all experts that PGS 2.0 can be defined as biopsy at the blastocyst stage followed by comprehensive chromosome screening and possibly combined with vitrification. Most agree that mosaicism is less of an issue at the blastocyst stage than at the cleavage stage but whether mosaicism is no issue at all at the blastocyst stage is currently called into question.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

A questionnaire was developed on the three major aspects of PGS 2.0: the Why, with general questions such as PGS 2.0 indications; the How, specifically on genetic analysis methods; the When, on the ideal method and timing of embryo biopsy. Thirty-five colleagues have been selected to address these questions on the basis of their experience with PGS, and demonstrated by peer-reviewed publications, presentations at meetings and participation in the discussion. The first group of experts who were asked about 'The Why' comprised fertility experts, the second group of molecular biologists were asked about 'The How' and the third group of embryologists were asked about 'The When'. Furthermore, the geographical distribution of the experts has been taken into account. Thirty have filled in the questionnaire as well as actively participated in the redaction of the current paper.

MAIN RESULTS AND THE ROLE OF CHANCE

The 30 participants were from Europe (Belgium, Germany, Greece, Italy, Netherlands, Spain, UK) and the USA. Array comparative genome hybridization is the most widely used method amongst the participants, but it is slowly being replaced by massive parallel sequencing. Most participants offering PGS 2.0 to their patients prefer blastocyst biopsy. The high efficiency of vitrification of blastocysts has added a layer of complexity to the discussion, and it is not clear whether PGS in combination with vitrification, PGS alone, or vitrification alone, followed by serial thawing and eSET will be the favoured approach. The opinions range from in favour of the introduction of PGS 2.0 for all IVF patients, over the proposal to use PGS as a tool to rank embryos according to their implantation potential, to scepticism towards PGS pending a positive outcome of robust, reliable and large-scale RCTs in distinct patient groups.

LIMITATIONS, REASONS FOR CAUTION

Care was taken to obtain a wide spectrum of views from carefully chosen experts. However, not all invited experts agreed to participate, which explains a lack of geographical coverage in some areas, for example China. This paper is a collation of current practices and opinions, and it was outside the scope of this study to bring a scientific, once-and-for-all solution to the ongoing debate.

WIDER IMPLICATIONS OF THE FINDINGS

This paper is unique in that it brings together opinions on PGS 2.0 from all different perspectives and gives an overview of currently applied technologies as well as potential future developments. It will be a useful reference for fertility specialists with an expertise outside reproductive genetics.

LARGE SCALE DATA

none.

STUDY FUNDING AND COMPETING INTERESTS

No specific funding was obtained to conduct this questionnaire.

Clinical application of next-generation sequencing in preimplantation genetic diagnosis cycles for Robertsonian and reciprocal translocations

PURPOSE

The purpose of this study was to apply next-generation sequencing (NGS) technology to identify chromosomally normal embryos for transfer in preimplantation genetic diagnosis (PGD) cycles for translocations.

METHODS

A total of 21 translocation couples with a history of infertility and repeated miscarriage presented at our PGD clinic for 24-chromosome embryo testing using copy number variation sequencing (CNV-Seq).

RESULTS

Testing of 98 embryo samples identified 68 aneuploid (69.4 %) and 30 (30.6 %) euploid embryos. Among the aneuploid embryos, the most common abnormalities were segmental translocation imbalances, followed by whole autosomal trisomies and monosomies, segmental imbalances of non-translocation chromosomes, and mosaicism. In all unbalanced embryos resulting from reciprocal translocations, CNV-Seq precisely identified both segmental imbalances, extending from the predicted breakpoints to the chromosome termini. From the 21 PGD cycles, eight patients had all abnormal embryos and 13 patients had at least one normal/balanced and euploid embryo available for transfer. In nine intrauterine transfer cycles, seven healthy babies have been born. In four of the seven children tested at 18 weeks gestation, the karyotypes matched with the original PGD results.

CONCLUSION

In clinical PGD translocation cycles, CNV-Seq displayed the hallmarks of a comprehensive diagnostic technology for high-resolution 24-chromosome testing of embryos, capable of identifying true euploid embryos for transfer.

The Effect of Preimplantation Genetic Screening on Implantation Rate in Women over 35 Years of Age

OBJECTIVE

Advanced maternal age (AMA) is an important factor in decreasing success of assisted reproductive technology by having a negative effect on the success rate of intra-cytoplasmic sperm injection (ICSI), particularly by increasing the rate of embryo aneuploidy. It has been suggested that the transfer of euploid embryos increases the implantation and pregnancy rates, and decreases the abortion rate. Preimplantation genetic screening (PGS) is a method for selection of euploid embryos. Past studies, however, have reported different results on the success of pregnancy after PGS in AMA. Investigating the pregnancy rate of ICSI with and without PGS in female partners over 35 years of age referred to infertility centers in Tehran.

MATERIALS AND METHODS

In this randomized controlled trial, 150 couples with the female partner over age of 35 were included. Fifty couples underwent PGS and the remaining were used as the control group. PGS was carried out using fluorescent in situ hybridization (FISH) for chromosomes 13, 18, 21, X and Y. Results of embryo transfer following PGS were evaluated and compared with those in the control group.

RESULTS

Implantation rates obtained in the PGS and control groups were 30 and 32% respectively and not significantly different (P>0.05).

CONCLUSION

PGS for chromosomes 13, 18, 21, X and Y does not increase implantation rate in women over 35 years of age and therefore the regular use of PGS in AMA is not recommended.

The Impact of Biopsy on Human Embryo Developmental Potential during Preimplantation Genetic Diagnosis

Preimplantation Genetic Diagnosis and Screening (PGD/PGS) for monogenic diseases and/or numerical/structural chromosomal abnormalities is a tool for embryo testing aimed at identifying nonaffected and/or euploid embryos in a cohort produced during an IVF cycle. A critical aspect of this technology is the potential detrimental effect that the biopsy itself can have upon the embryo. Different embryo biopsy strategies have been proposed. Cleavage stage blastomere biopsy still represents the most commonly used method in Europe nowadays, although this approach has been shown to have a negative impact on embryo viability and implantation potential. Polar body biopsy has been proposed as an alternative to embryo biopsy especially for aneuploidy testing. However, to date no sufficiently powered study has clarified the impact of this procedure on embryo reproductive competence. Blastocyst stage biopsy represents nowadays the safest approach not to impact embryo implantation potential. For this reason, as well as for the evidences of a higher consistency of the molecular analysis when performed on trophectoderm cells, blastocyst biopsy implementation is gradually increasing worldwide. The aim of this review is to present the evidences published to date on the impact of the biopsy at different stages of preimplantation development upon human embryos reproductive potential.

The ART of selecting the best embryo: A review of early embryonic mortality and bovine embryo viability assessment methods

Animal reproductive biotechnology is continually evolving. Significant advances have been made in our understanding of early embryonic mortality and embryo development in domestic animals, which has improved the selection and success of in vitro technologies. Yet our knowledge is still relatively limited such that identifying a single embryo with the highest chance of survival and development for transfer remains challenging. While invasive methods such as embryo biopsy can provide useful information regarding the genetic status of the embryos, morphological assessment remains the most common evaluation. A recent shift, however, favors alternative, adjunct approaches for non-invasive assessment of an embryo's viability and developmental potential. Various analytical techniques have facilitated the evaluation of cellular health through the metabolome, the assessment of end products of cellular metabolism, or by analyzing spent media for small RNAs. This review discusses the application of noninvasive approaches for ascertaining the health and viability of in vitro-produced bovine embryos. A comparative analysis of noninvasive techniques for embryo assessment currently being investigated in cattle and humans is also discussed.

Impact of whole-genome amplification on the reliability of pre-transfer cattle embryo breeding value estimates

Background

Genome-wide profiling of single-nucleotide polymorphisms is receiving increasing attention as a method of pre-implantation genetic diagnosis in humans and of commercial genotyping of pre-transfer embryos in cattle. However, the very small quantity of genomic DNA in biopsy material from early embryos poses daunting technical challenges. A reliable whole-genome amplification (WGA) procedure would greatly facilitate the procedure.

Results

Several PCR-based and non-PCR based WGA technologies, namely multiple displacement amplification, quasi-random primed library synthesis followed by PCR, ligation-mediated PCR, and single-primer isothermal amplification were tested in combination with different DNA extractions protocols for various quantities of genomic DNA inputs. The efficiency of each method was evaluated by comparing the genotypes obtained from 15 cultured cells (representative of an embryonic biopsy) to unamplified reference gDNA. The gDNA input, gDNA extraction method and amplification technology were all found to be critical for successful genome-wide genotyping. The selected WGA platform was then tested on embryo biopsies (n = 226), comparing their results to that of biopsies collected after birth. Although WGA inevitably leads to a random loss of information and to the introduction of erroneous genotypes, following genomic imputation the resulting genetic index of both sources of DNA were highly correlated (r = 0.99, P<0.001).

Conclusion

It is possible to generate high-quality DNA in sufficient quantities for successful genome-wide genotyping starting from an early embryo biopsy. However, imputation from parental and population genotypes is a requirement for completing and correcting genotypic data. Judicious selection of the WGA platform, careful handling of the samples and genomic imputation together, make it possible to perform extremely reliable genomic evaluations for pre-transfer embryos.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-889) contains supplementary material, which is available to authorized users.

Neonatal outcome after preimplantation genetic diagnosis

OBJECTIVE

To examine whether embryo biopsy for preimplantation genetic diagnosis (PGD) influences neonatal outcomes.

DESIGN

Prospective follow-up cohort.

SETTING

Tertiary university-affiliated medical center.

PATIENT(S)

242 children born after PGD, 242 children born after intracytoplasmic sperm injection (ICSI) (158 singletons and 42 twins pairs in each group), and 733 children born after a spontaneous conception (SC) (493 singletons, 120 twins pairs), matched for maternal age, parity, and body mass index.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Gestational age, birth weight, prematurity (<37 and <34 weeks), low birth weight (<2,500 g, very low birth weight, <1,500 g), and intrauterine growth restriction (<10th percentile for gestational age).

RESULT(S)

For singletons, the mean birth weight was higher after SC compared with ICSI but not compared with PGD. Mean gestational ages were lower after PGD and ICSI compared with SC. The low birth weight and intrauterine growth restriction rates were 4.4%, 12.0%, and 5.7% and 5.1%, 9.5%, and 5.5% for PGD, ICSI, and SC, respectively. Similar results were found when controlled for the number of embryos transferred and cryopreservation. The results for twins exhibited similar but less statistically significant trends. Polar body and blastomere biopsies provided similar outcomes.

CONCLUSION(S)

Embryo biopsy itself did not cause intrauterine growth restriction or low birth weight compared with SC, despite lower gestational ages with PGD. The worsened outcomes in ICSI compared with PGD pregnancies may be due to the infertility itself.

Preimplantation genetic screening: back to the future

All agree that in hindsight the rapid adoption of preimplantation genetic screening (PGS) using cleavage stage biopsy and fluorescence in situ hybridization (FISH) in routine clinical practice without proper evaluation of (cost-)effectiveness basically resulted in couples paying more money for a less effective treatment. Now, almost 20 years later, we are on the verge of a new era of PGS. But have things really changed or are we simply going back to the future?

Arrested human embryos are more likely to have abnormal chromosomes than developing embryos from women of advanced maternal age

Background

Aneuploidy is one of the major factors that result in low efficiency in human infertility treatment by in vitro fertilization (IVF). The development of DNA microarray technology allows for aneuploidy screening by analyzing all 23 pairs of chromosomes in human embryos. All chromosome screening for aneuploidy is more accurate than partial chromosome screening, as errors can occur in any chromosome. Currently, chromosome screening for aneuploidy is performed in developing embryos, mainly blastocysts. It has not been performed in arrested embryos and/or compared between developing embryos and arrested embryos from the same IVF cycle.

Methods

The present study was designed to examine all chromosomes in blastocysts and arrested embryos from the same cycle in patients of advanced maternal ages. Embryos were produced by routine IVF procedures. A total of 90 embryos (45 blastocysts and 45 arrested embryos) from 17 patients were biopsied and analyzed by the Agilent DNA array platform.

Results

It was found that 50% of the embryos developed to blastocyst stage; however, only 15.6% of the embryos (both blastocyst and arrested) were euploid, and most (84.4%) of the embryos had chromosomal abnormalities. Further analysis indicated that 28.9% of blastocysts were euploid and 71.1% were aneuploid. By contrast, only one (2.2%) arrested embryo was euploid while others (97.8%) were aneuploid. The prevalence of multiple chromosomal abnormalities in the aneuploid embryos was also higher in the arrested embryos than in the blastocysts.

Conclusions

These results indicate that high proportions of human embryos from patients of advanced maternal age are aneuploid, and the arrested embryos are more likely to have abnormal chromosomes than developing embryos.

Successful haematopoietic stem cell transplantation in 44 children from healthy siblings conceived after preimplantation HLA matching

Haematopoietic stem cell transplantation (HSCT) remains the best therapeutic option for many acquired and inherited paediatric haematological disorders. Unfortunately, the probability of finding an HLA matched donor is limited. An alternative technique is PGD combined with HLA matching, which offers the possibility of selecting unaffected embryos that are HLA compatible with the sick child, with the aim of possible use of stem cells from the resulting baby in future. Since the first successful report for Fanconi anaemia a decade ago, the therapeutic success of this technique was reported in a few cases and for a limited number of disorders. Here, we report full recovery of 44 sick children who received HSCT from healthy infants conceived after pre-implantation HLA matching for the following 10 indications; beta-thalassaemia, Wiskott-Aldrich syndrome, Fanconi anaemia, sickle cell anaemia, acute myeloid leukaemia, acute lymphoblastic leukaemia, Glanzmann's thrombasthaenia, Diamond-Blackfan anaemia, X-linked adrenoleukodystrophy and mucopolysaccharidosis type I. No serious complications were observed among recipients and donors. Graft failure occurred in four children with beta-thalassaemia where a second HSCT was planned. Preimplantation HLA matching is a reliable technique and provides a realistic option for couples seeking treatment for an affected child when no HLA-matched donor is available.

Delivery of a chromosomally normal child from an oocyte with reciprocal aneuploid polar bodies

Purpose

To demonstrate that a euploid embryo derived from an oocyte with reciprocal aneuploid polar bodies is capable of producing a chromosomally normal child.

Methods

A case report of maternal MI error compensation where single nucleotide polymorphism (SNP) microarray based comprehensive chromosome screening (CCS) was performed on the 1st and 2nd polar body, the resulting embryo, and newborn DNA.

Results

CCS performed after embryo transfer identified a chromosomally normal embryo that resulted from an oocyte with reciprocal aneuploid polar bodies. The first polar body was found to be missing a single chromatid derived from chromosome 21 and the second polar body possessed an extra chromatid derived from chromosome 21. Compensation of the maternal meiotic error was verified by CCS analysis of a trophectoderm biopsy from the resulting blastocyst which was euploid for all 23 pairs of chromosomes. DNA fingerprinting and CCS of the resulting newborn confirmed a chromosomally normal child, demonstrating the developmental potential of an oocyte with reciprocal aneuploid polar bodies.

Conclusions

This is the first case report demonstrating the reproductive potential of a chromosomally normal embryo derived from an oocyte which had undergone meiosis I error. Systematic investigation into the frequency of meiosis I error compensation and the negative predictive value of polar body aneuploidy screening for reproductive potential should be conducted in order to confirm clinical relevance.

Establishment of hESC lines from the inner cell mass of blastocyst-stage embryos and single blastomeres of 4-cell stage embryos

More than 600 human embryonic stem cell (hESC) lines have been reported today at the human European Embryonic Stem Cell Registry ( http://www.hescreg.eu/ ). Despite these high numbers, there are currently no general protocols for derivation, culture, and characterization of hESC. Moreover, data on the culture of the embryo used for the derivation (medium, day of ICM isolation) are usually not available but can have an impact on the derivation rate. We present here the protocols for derivation, culture and characterization as we applied them for the 22 hESC lines (named VUB-hESC) in our laboratory.

Preimplantation genetic diagnosis in female and male carriers of reciprocal translocations: clinical outcome until delivery of 312 cycles

Carriers of reciprocal translocations (rcp) are known to be at risk for reproductive difficulties. Preimplantation genetic diagnosis (PGD) is one of the options these carriers have to try in order to fulfil their desire to have a child. In the present study, we retrospectively looked at the results of 11 years (1997-2007) of PGD for rcp in our center to improve the reproductive counseling of these carriers. During this period 312 cycles were performed for 69 male and 73 female carriers. The mean female age was 32.8 years, the mean male age 35.8 years. Most carriers were diagnosed with a translocation because of fertility problems or recurrent miscarriages, and most of them opted for PGD to avoid these problems. In 150 of the 312 cycles, embryo transfer (ET) was feasible and 40 women had a successful singleton or twin pregnancy. This gives a live birth delivery rate of 12.8% per started cycle and of 26.7% per cycle with ET. Owing to the large number of abnormal embryos, PGD cycles for rcp often lead to cancellation of ET, explaining the low success rate when expressed per cycle with oocyte pick-up. Once ET was feasible, the live birth delivery rate was similar to that of PGD in general at our center. PGD is therefore an established option for specific reciprocal translocation carriers.

Preimplantation genetic diagnosis (PGD) for Huntington's disease: the experience of three European centres

This study provides an overview of 13 years of experience of preimplantation genetic diagnosis (PGD) for Huntington's disease (HD) at three European PGD centres in Brussels, Maastricht and Strasbourg. Information on all 331 PGD intakes for HD, couples' reproductive history, PGD approach, treatment cycles and outcomes between 1995 and 2008 were collected prospectively. Of 331 couples for intake, 68% requested direct testing and 32% exclusion testing (with a preponderance of French couples). At the time of PGD intake, 39% of women had experienced one or more pregnancies. A history of pregnancy termination after prenatal diagnosis was observed more frequently in the direct testing group (25%) than in the exclusion group (10%; P=0.0027). PGD workup was based on two approaches: (1) direct testing of the CAG-triplet repeat and (2) linkage analysis using intragenic or flanking microsatellite markers of the HTT gene. In total, 257 couples had started workup and 174 couples (70% direct testing, 30% exclusion testing) completed at least one PGD cycle. In total, 389 cycles continued to oocyte retrieval (OR). The delivery rates per OR were 19.8%, and per embryo transfer 24.8%, resulting in 77 deliveries and the birth of 90 children. We conclude that PGD is a valuable and safe reproductive option for HD carriers and couples at risk of transmitting HD.

Seven years of experience of preimplantation HLA typing: a clinical overview of 327 cycles

Preimplantation human leukocyte antigen (HLA) typing allows the birth of healthy children who are potential donors of stem cells for their affected siblings. This technique can be used for acquired diseases such as leukaemia or can be used for single-gene disorders such as thalassaemia. This retrospective study presents clinical data obtained from 171 couples who had undergone 327 preimplantation HLA typing cycles: 262 cycles for HLA typing in combination with mutation analysis and 65 cycles for the sole purpose of HLA typing. Of the diagnosed embryos 17.6% were found to be HLA matched. Embryo transfer was performed in 212 cycles, 34.9% clinical pregnancy rate per transfer was achieved and 59 healthy and HLA-compatible children were born. Twenty-one sick children have been cured through haemopoietic stem cell transplantation. The effect of maternal age and ovarian reserve on reproductive outcome was assessed retrospectively. The data demonstrated that, once a mutation-free and HLA-compatible embryo was found, clinical pregnancy rate did not differ statistically significantly despite the presence of some cycle-related limitations such as advanced maternal age and/or diminished ovarian reserve. Preimplantation HLA typing is an effective therapeutic tool for curing an affected sibling even for poor-prognosis patients. Preimplantation human leukocyte antigent (HLA) typing allows the birth of healthy children who are potential donors of stem cells for their affected siblings. This technique can be used for acquired diseases such as leukaemia or can be used for single-gene disorders such as thalassaemia. This study presents clinical data obtained from 171 couples who underwent 327 preimplantation HLA-typing cycles. Of these, 262 cycles were performed for HLA typing in combination with mutation analysis and 65 cycles were performed for the sole purpose of HLA typing. A total of 17.6% of the diagnosed embryos were found to be HLA matched. Embryo transfer was performed in 212 cycles. The clinical pregnancy rate per transfer was 34.9% and 59 healthy and HLA compatible children were born. Twenty-one sick children have been cured through haemopoietic stem cell transplantation. The effect of maternal age and ovarian reserve on reproductive outcome was assessed retrospectively. The data demonstrated that, once a mutation-free and HLA-compatible embryo was found, clinical pregnancy rates did not differ statistically significantly by the presence of some cycle-related limitations such as advanced maternal age and/or diminished ovarian reserve. Preimplantation HLA typing is an effective therapeutic tool for curing an affected sibling even for poor-prognosis patients.

Preimplantation genetic screening: a systematic review and meta-analysis of RCTs

BACKGROUND

Preimplantation genetic screening (PGS) has increasingly been used in the past decade. Here we present a systematic review and meta-analysis of RCTs on the effect of PGS on the probability of live birth after IVF.

METHODS

PubMed and trial registers were searched for RCTs on PGS. Trials were assessed following predetermined quality criteria. The primary outcome was live birth rate per woman, secondary outcomes were ongoing pregnancy rate, miscarriage rate, multiple pregnancy rate and pregnancy outcome.

RESULTS

Nine RCTs comparing IVF with and without PGS were included in our meta-analysis. Fluorescence in situ hybridization was used in all trials and cleavage stage biopsy was used in all but one trial. PGS significantly lowered live birth rate after IVF for women of advanced maternal age (risk difference: -0.08; 95% confidence interval: -0. 13 to -0.03). For a live birth rate of 26% after IVF without PGS, the rate would be between 13 and 23% using PGS. Trials where PGS was offered to women with a good prognosis and to women with repeated implantation failure suggested similar outcomes.

CONCLUSIONS

There is no evidence of a beneficial effect of PGS as currently applied on the live birth rate after IVF. On the contrary, for women of advanced maternal age PGS significantly lowers the live birth rate. Technical drawbacks and chromosomal mosaicism underlie this inefficacy of PGS. New approaches in the application of PGS should be evaluated carefully before their introduction into clinical practice.

Singling out genetic disorders and disease

Preimplantation genetic diagnosis (PGD) involves testing of single cells biopsied from oocytes and/or embryos generated in vitro. As only embryos unaffected for a given genetic condition are transferred to the uterus, it avoids prenatal diagnosis and termination of pregnancy. Follow-up data from PGD pregnancies, deliveries and children show an acceptable live birth rate and, so far, no detrimental effects of the procedure have been observed. Of course, the long-term health outcome is currently unknown. PGD was first performed in 1990 and remained an experimental procedure for a number of years. Now, two decades later, it is regarded as an established alternative to prenatal diagnosis: its use has expanded, the range of applications has broadened, and continuous technical progress in single-cell testing has led to high levels of efficiency and accuracy. The current gold standard methods (single-cell multiplex-PCR for monogenic diseases and interphase fluorescence in situ hybridization for chromosomal aberrations) are being replaced by single-cell whole genome amplification and array technology. These generalized methods substantially reduce the pre-PGD workload and allow more automated genome-wide analysis. The implementation of laboratory accreditation schemes brings the field at the same level of routine diagnostics. This article reviews the state of the art and considers indications, accuracy and current technical changes in the field of PGD.

Slow and ultrarapid cryopreservation of biopsied mouse blastocysts and its effect on DNA integrity index

PURPOSE

To evaluate the effect of slow and ultra-rapid freezing on biopsied blastocysts' DNA integrity.

METHODS

Forty eight mouse blastocysts were biopsied of which 16 were cryopreserved by slowly freezing and 17 by vitrification. Fourteen intact blastocysts were slowly cryopreserved and 24 were vitrified. Eighteen fresh intact blastocysts and fifteen biopsied blastocysts served as controls. The DNA integrity index of all blastocysts was evaluated using (TUNEL) staining and confocal imaging

RESULTS

Both slow freezing and vitrification of biopsied blastocysts induced apoptosis to a similar extent. Biopsying blastocysts before vitrification resulted in less apoptosis than vitrification of intact blastocysts.

CONCLUSION

Slow freezing and vitrification are equal options for preservation of biopsied blastocysts as regards the DNA integrity index (DII). Biopsied blastocysts better tolerate vitrification than intact expanded blastocysts.

Increased efficiency of preimplantation genetic diagnosis for aneuploidy by testing 12 chromosomes

One of the most important factors in increasing the screening potential of preimplantation genetic diagnosis (PGD) for aneuploidy is to increase the number of chromosomes analysed. Inclusion of chromosomes 8, 14 and 20 to the standard set of chromosomes X, Y, 13, 15, 16, 17, 18, 21 and 22 allows the analysis of 12 chromosomes in three rounds of fluorescent in-situ hybridization (FISH) without decreasing the efficiency of the technique. Pregnancy rate was significantly increased when only embryos that had been diagnosed as normal for the 12 chromosomes analysed were transferred compared with transfer of embryos with any abnormality for chromosomes 8, 14 or 20 (P < 0.05). This study proves that the high efficiency and practical feasibility of FISH analysis of 12 chromosomes in PGD for aneuploidy is a superior approach than the standard nine-chromosome analysis in order to screen for abnormalities.

Impact of cleavage-stage embryo biopsy in view of PGD on human blastocyst implantation: a prospective cohort of single embryo transfers

BACKGROUND

Human embryo biopsy is performed for preimplantation genetic diagnosis (PGD). The impact of 1- or 2-cell removal at cleavage-stage on future embryo development and implantation capacity is highly debated.

METHODS

In order to explore this issue further, a cohort of Day 5 single embryo transfers was analysed prospectively for embryological and clinical outcome. All transferred embryos resulted from 8-cell embryos on Day 3, from which subsequently either one cell (group I, n = 182) or two cells (group II, n = 259) were removed, or on which no invasion by means of embryo biopsy was performed (group III, control group, n = 702). RESULTS Blastocyst formation was significantly better in group III compared with group II, and similar to group I. Group I and group II did not differ in Day 3 nor in Day 5 embryo development. The overall live birth rate was significantly higher in group I (37.4%, CI 29.0-47.4%) than in group II (22.4%, CI 17.0-28.9%), and comparable to the reference ICSI population (35.0%, CI 30.8-39.7%).

CONCLUSIONS

The clinical outcome of 1-cell biopsy was significantly better than that of 2-cell biopsy, even when adjusted for availability of genetically transferable embryos.

Report on a consecutive series of 581 children born after blastomere biopsy for preimplantation genetic diagnosis

BACKGROUND

Preimplantation genetic diagnosis (PGD) and subsequently preimplantation genetic screening (PGS) have been introduced since 1990. The difference from the already existing in vitro fertilization (IVF) technology, using intracytoplasmic sperm injection (ICSI), was the embryo biopsy at day 3 after fertilization. Although healthy children post-PGD/PGS have been born, the question of whether embryo biopsy could have any harmful effects has to be studied on large series in a prospective manner.

METHODS

A prospective cohort study was undertaken from 1992 until 2005, using the same approach as for the follow-up of IVF and ICSI children conceived in the same centre. Questionnaires were sent to physicians and parents at conception and at delivery. Children were examined at 2 months of age by trained clinical geneticists whenever possible.

RESULTS

Data collected on 581 post-PGD/PGS children showed that term, birthweight and major malformation rates were not statistically different from that of 2889 ICSI children, with overall rates of major malformation among these post-PGD/PGS and ICSI children being 2.13 and 3.38%, respectively (odds ratio [OR]: 0.62; exact 95% confidence limits [95% CL]: 0.31-1.15). However, the overall perinatal death rate was significantly higher among post-PGD/PGS children compared with ICSI children (4.64 versus 1.87%; OR: 2.56; 95% CL: 1.54-4.18). When stratified for multiple births, perinatal death rates among PGD/PGS singleton and ICSI singleton children were similar (1.03 versus 1.30%; OR: 0.83; 95% CL: 0.28-2.44), but significantly more perinatal deaths were seen in post-PGD/PGS multiple pregnancies compared with ICSI multiple pregnancies (11.73 versus 2.54%; OR: 5.09; 95% CL: 2.80-9.90). The overall misdiagnosis rate was below 1%.

CONCLUSIONS

Embryo biopsy does not add risk factors to the health of singleton children born after PGD or PGS. The perinatal death rate in multiple pregnancies is such that both caution and long-term follow-up are required.

The incidence of monozygotic twinning following PGD is not increased

BACKGROUND

Monozygotic (MZ) twin pregnancies are associated with increased perinatal mortality and morbidity, and risk of congenital anomalies. The causes of MZ twinning in humans are unclear but the incidence may increase after PGD, for example, as a result of holes created in the zona pellucida. We compared the incidence of MZ twin pregnancies in ICSI cycles with PGD, versus ICSI cycles without PGD.

METHODS

In this retrospective comparative cohort study, we analysed incidence of twin pregnancies in unselected patients undergoing ICSI and PGD (group A; 1992 cycles) with blastocyst transfer at Day 5, versus a period-matched control population of unselected patients undergoing ICSI and blastocyst transfer at Day 5 without PGD (group B; 2429 cycles) from January 2001 to December 2006.

RESULTS

Clinical pregnancy per embryo transfer was established in 618/1992 (31.0%) and 947/2429 (39.0%) in group A versus B, respectively (P < 0.01). Overall MZ twin rate was 29/4421 (0.7%) per embryo transfer and 29/1565 (1.9%) per established clinical pregnancy. The incidence of MZ twinning per established clinical pregnancy did not differ between groups (1.5 versus 2.1%, group A and B, respectively). In group A, seven MZ twins were born versus 19 MZ twins in group B. In group B, one MZ twin pregnancy resulted in two stillbirths. In group A, two MZ twins had severe congenital malformations versus none in group B.

CONCLUSIONS

The incidence of MZ twinning was not increased in PGD compared with regular ICSI with blastocyst transfer. This information is useful in counselling patients about potential risks of PGD.

PGD for monogenic disorders: aspects of molecular biology

Preimplantation genetic diagnosis (PGD) for monogenic diseases has known a considerable evolution since its first application in the early 1990s. Especially the technical aspects of the genetic diagnosis itself, the single-cell genetic analysis, has constantly evolved to reach levels of accuracy and efficiency nearing those of genetic diagnosis on regular DNA samples. In this review, we will focus on the molecular biological techniques that are currently in use in the most advanced centers for PGD for monogenic disorders, including multiplex polymerase chain reaction (PCR) and post-PCR diagnostic methods, whole genome amplification (WGA) and multiple displacement amplification (MDA). As it becomes more and more clear that when it comes to ethically difficult indications, PGD goes further than prenatal diagnosis (PND), we will also briefly discuss ethical issues.

Preimplantation genetic diagnosis for myotonic dystrophy type 1: upon request to child

Preimplantation genetic diagnosis (PGD) is an alternative to prenatal diagnosis for patients at risk of transmitting an inherited disease such as myotonic dystrophy type 1(DM1) to their offspring. In this paper, the clinical application of preimplantation diagnosis for DM1 upon request to children born is described in a large cohort of risk couples. PGD could be offered to all 78 couples opting for PGD regardless of the triplet repeat size. The incidence of major complications was minimalised following a careful assessment in affected DM1 females anticipating possible cardiological, obstetrical and anaesthetical problems. A live-birth delivery rate per cycle with oocyte retrieval of 20% was the outcome. Forty-eight of the 49 children born are in good health and have normal psychomotor development.

[Mastenbroek controversy or how much ink is spilled on preimplantation genetic screening subject]

Preimplantation genetic screening (PGS) of in vitro fertilization (IVF) embryos has been used for advanced maternal age, repeated miscarriages and repeated implantation failure indications. Several non-randomized studies have been published, showing increased implantation rates, decreased miscarriages and trisomy rates. So PGS seemed to improve prognosis for this particular population. In 2004, a prospective randomized study tempered those results, being unable to demonstrate any significant difference of live birth rate with and without PGS in case of advanced maternal age. In July 2007, another multicenter randomized double-blind trial definitely reopened the controversy, reporting that PGS did not increase but instead significantly reduced pregnancy and live birth rates after IVF in women 35 years of age or older. The debate about efficiency and usefulness of PGS is ongoing and other powered randomized studies will be needed to conclude about real PGS usefulness.

A prospective randomized controlled trial of preimplantation genetic screening in the "good prognosis" patient

OBJECTIVE

To determine whether the routine use of preimplantation genetic screening (PGS) in "good prognosis" women improves in vitro fertilization (IVF) cycle outcome.

DESIGN

Randomized, controlled, prospective clinical study.

SETTING

Private infertility clinic.

PATIENT(S)

Infertile women predicted to have a good prognosis as defined by: age <39 years, normal ovarian reserve, body mass index <30 kg/m(2), presence of ejaculated sperm, normal uterus, <or=2 previous failed IVF cycles.

INTERVENTION(S)

Patients were randomized to the PGS group or the control group on day 3 after oocyte retrieval; 23 women underwent blastomere biopsy on day 3 after fertilization (PGS group), and 24 women underwent routine IVF (control group). All embryos were transferred on day 5 or 6 after fertilization.

MAIN OUTCOME MEASURE(S)

Pregnancy, implantation, multiple gestation, and live birth rates.

RESULT(S)

No statistically significant differences were found between the PGS and control groups with respect to clinical pregnancy rate (52.4% versus 72.7%). However, the embryo implantation rate was statistically significantly lower for the PGS group (31.7% versus 62.3%) as were the live birth rate (28.6% versus 68.2%) and the multiple birth rate (9.1% versus 46.7%).

CONCLUSION(S)

In a "good prognosis" population of women, PGS does not appear to improve pregnancy, implantation, or live birth rates.

The current status of preimplantation genetic screening: British Fertility Society Policy and Practice Guidelines

Preimplantation genetic screening (PGS) has been proposed as a method to improve the success rates of assisted conception in certain indications. Most commonly the technique involves analysing part of the karyotype of one or two biopsied blastomeres by fluorescence in situ hybridisation and thus detecting aneuploid embryos which are then not transferred into the uterus. Proposed indications include advanced maternal age, repeated IVF failure and recurrent miscarriage. While there are a considerable number of reports of the use of this technique, there are only two randomised controlled trials reported at present, both for the indication of advanced maternal age. Neither show an increase in live birth rate, and indeed the more recent (using a relatively low age cut-off of 35 years) suggests that live birth rate is reduced by the use of PGS. Methodological aspects of both studies are discussed. It remains possible that PGS may be of benefit under certain circumstances. However at present patients should be informed that there is no robust evidence that PGS for advanced maternal age improves live birth rate per cycle started, and PGS should preferably be offered within the context of robustly designed randomised trials performed in suitably experienced centres.

The effect of blastomere biopsy on preimplantation mouse embryo development and global gene expression

The blastomere biopsy procedure does not affect preimplantation embryo development or global patterns of gene expression in a mouse model of Preimplantation Genetic Testing (PGT). However, zona breaching, which is inherent to the blastomere biopsy procedure, causes significant premature and sometimes abnormal hatching.

Reliability of sex determination in ovine embryos using amelogenin gene (AMEL)

Sex specific sequence variability of the amelogenin gene has been used for sex determination in the family of Bovidae. In our study, suitability and reliability of the amelogenin gene for ovine sex determination in embryos was studied. The specificity of the method was previously demonstrated by testing 579 blood samples from several Spanish sheep breeds (161 males and 198 females). No amplification failures and very high agreement between genotypic and phenotypic sex was found (578/579), in contrast to humans, where errors in sex determination has been reported because of mutations in AMELX or AMELY genes. However, one female animal showed a male genotypic sex, being the most plausible explanation that a recombination event has happened during the meiosis. In our study only 0.17% (1/579) of the samples tested has been misdiagnosed using the amelogenin gene. Finally, 1-10 cells from each of 67 compact morulae were aspirated through the zona pellucida, and genotyped for sex determination. The efficiency in sex determination was 95 and 98% when more than two and more than three cells were sampled, respectively. The total time required for the genetic test, was less than 4h. These results confirm that the amelogenin gene can be used for rapid sex determination in ovine embryos, with a high efficiency and accuracy (100%) when three or more cells are sampled, allowing transferring sexed fresh embryos in MOET programmes. To our knowledge, this was the first time that sex determination using the amelogenin gene was performed in ovine embryos.

In vitro fertilization with preimplantation genetic screening

BACKGROUND

Pregnancy rates in women of advanced maternal age undergoing in vitro fertilization (IVF) are disappointingly low. It has been suggested that the use of preimplantation genetic screening of cleavage-stage embryos for aneuploidies may improve the effectiveness of IVF in these women.

METHODS

We conducted a multicenter, randomized, double-blind, controlled trial comparing three cycles of IVF with and without preimplantation genetic screening in women 35 through 41 years of age. The primary outcome measure was ongoing pregnancy at 12 weeks of gestation. The secondary outcome measures were biochemical pregnancy, clinical pregnancy, miscarriage, and live birth.

RESULTS

Four hundred eight women (206 assigned to preimplantation genetic screening and 202 assigned to the control group) underwent 836 cycles of IVF (434 cycles with and 402 cycles without preimplantation genetic screening). The ongoing-pregnancy rate was significantly lower in the women assigned to preimplantation genetic screening (52 of 206 women [25%]) than in those not assigned to preimplantation genetic screening (74 of 202 women [37%]; rate ratio, 0.69; 95% confidence interval [CI], 0.51 to 0.93). The women assigned to preimplantation genetic screening also had a significantly lower live-birth rate (49 of 206 women [24%] vs. 71 of 202 women [35%]; rate ratio, 0.68; 95% CI, 0.50 to 0.92).

CONCLUSIONS

Preimplantation genetic screening did not increase but instead significantly reduced the rates of ongoing pregnancies and live births after IVF in women of advanced maternal age. (Current Controlled Trials number, ISRCTN76355836 [controlled-trials.com].).

Clinical outcome of preimplantation genetic diagnosis for cystic fibrosis: the Brussels' experience

Preimplantation genetic diagnosis is an alternative for prenatal diagnosis that makes it possible to perform the diagnosis of a chromosomal or monogenic disorder at the preimplantation embryo level. Cystic fibrosis is one of the monogenic diseases for which PGD can be performed. In this study, we looked at the requests and PGD cycles for this particular disorder over an 11-year period. Sixty-eight percent of the requests eventually led to at least one complete PGD cycle. In 80% of the cycles, an embryo transfer was performed and an ongoing pregnancy was obtained in 22.2% of the cycles with oocyte retrieval. After embryo transfer, a couple had 27.8% chance of giving birth to a liveborn child. No misdiagnosis was recorded. The rate of perinatal deaths/stillborn children was relatively high, but no excess of major congenital anomalies was observed in the surviving children.