Positive outcome after preimplantation diagnosis of aneuploidy in human embryos

Accurate single cell 24 chromosome aneuploidy screening using whole genome amplification and single nucleotide polymorphism microarrays

OBJECTIVE

To develop and validate a whole genome amplification and single nucleotide polymorphism (SNP) microarray protocol for accurate single cell 24 chromosome aneuploidy screening.

DESIGN

Prospective, randomized, and blinded study.

SETTING

Academic reproductive medicine center.

PATIENT(S)

Multiple euploid and aneuploid cell lines were obtained from a public repository and blastomeres were obtained after biopsy of cleavage stage embryos from 78 patients undergoing IVF.

MAIN OUTCOME MEASURE(S)

Accuracy of copy number assignment and consistency of individual SNPs, whole chromosomes, and single cell aneuploidy status were determined.

INTERVENTION(S)

None.

RESULT(S)

Single cells extracted from karyotypically defined cell lines provided 99.2% accuracy for individual SNPs, 99.8% accuracy for whole chromosomes, and 98.6% accuracy when applying a quality control threshold for the overall assignment of aneuploidy status. The concurrence for more than 80 million SNPs in 335 single blastomeres was 96.5%.

CONCLUSION(S)

We have established and validated a SNP microarray-based single cell aneuploidy screening technology. Clinical validation studies are underway to determine the predictive value of this methodology.

Single-cell DNA and FISH analysis for application to preimplantation genetic diagnosis

Preimplantation genetic testing, which includes preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS), is a form of a very early prenatal testing. The goal of this method is to avoid transfer of embryos affected with a specific genetic disease or condition. This unit describes the steps involved in amplifying DNA from a single blastomere and specific assays for detecting a variety of DNA mutations. For some assays, whole-genome amplification by primer-extension preamplification (PEP) is performed prior to analysis. Support protocols describe the biopsy of one or two blastomeres from the developing preimplantation embryo, isolation for further investigation of all blastomeres from embryos shown to have the mutant allele, and isolation of single lymphocytes or lymphoblastoid cells as models for single-cell DNA analysis. A procedure for FISH analysis on single interphase blastomeres is provided along with support protocols for probe preparation and probe validation, which is recommended as a preliminary step before performing any PGD or PGS FISH analysis.

Role of Preimplantation Genetic Diagnosis (PGD) in Current Infertility Practice

Chromosome imbalances are the leading cause of pregnancy loss in humans and play major roles in male and female infertility. Within the past two decades, the development and application of preimplantation genetic diagnosis (PGD) has played an important role in infertility practices worldwide. The purpose of this review is to discuss, how PGD may be applied in combating numerical chromosomal abnormalities and in Robertsonian and reciprocal chromosome translocations. We shall consider prevalence and risk of each aberration, interchromosomal effects and rationale behind use of PGD in each case. Numerical chromosome abnormalities (aneuploidy and polyploidy) in particular affect a very high proportion of preimplantation embryos (~ 50%). Given that a majority of preimplantation embryos are aneuploid, PGD can be used to screen embryos and transfer euploid embryos to improve pregnancy rates and reduce spontaneous abortions. The rationale of utilize PGD to transfer only euploid embryos would seem sound, but controversies exist surrounding application of PGD for aneuploidy detection. To this end, we will discuss the dichotomy between favorable descriptive reports and less favorable randomized clinical trial data. This review will discuss the trend towards differing sources of embryonic DNA (e.g. polar body vs blastomere vs blastocyst) as well as development of novel technologies for 24 chromosomes analysis.

Clinical application of preimplantation genetic diagnosis

Preimplantation genetic diagnosis (PGD) is an early alternative to prenatal diagnosis that is suitable for a small group of patients who are at substantial risk of conceiving a pregnancy affected by a known genetic defect. Four centres are licensed to perform PGD in the UK. This article reviews the clinical experience of PGD at the Guy's and St Thomas' Centre for Preimplantation Genetic Diagnosis, now the busiest unit for PGD in the UK, and compares it with information from other centres in Europe. The results from the first 40 cycles of treatment and the 12 pregnancies arising from those cycles are detailed. It is our belief that PGD should be seen as an extension of a clinical genetic service, rather than an arm of assisted conception. Making the distinction between treatment for infertility and prevention of genetic defect as part of genetic service provision may improve access to health service funding for patients deserving of PGD.

The role of preimplantation genetic diagnosis in diagnosing embryo aneuploidy

PURPOSE OF REVIEW

Use of preimplantation genetic diagnosis to improve in-vitro fertilization outcomes is reviewed.

RECENT FINDINGS

Many embryos produced in vitro contain chromosomal abnormalities and have little potential for forming a viable pregnancy. The most commonly used method for preimplantation genetic diagnosis involves embryo biopsy on day 3 of development, followed by fluorescence in-situ hybridization analysis of 5-12 chromosomes. However, positive results have been more common with single-cell biopsy and the analysis of nine or more chromosomes, including 15, 16, 21, and 22. Comparative genomic hybridization, array-comparative genomic hybridization, and single-nucleotide polymorphism arrays analyze all chromosomes and, although technically demanding and requiring experience for successful use, improve the selection potential of preimplantation genetic diagnosis and minimize error rates. Recent data suggest that biopsy at the blastocyst stage may allow sampling of representative genetic material without compromising embryo viability. The optimal strategy for aneuploidy screening using preimplantation genetic diagnosis seems to be blastocyst biopsy at 5 days and comprehensive chromosome analysis (comparative genomic hybridization, array-comparative genomic hybridization, single-nucleotide polymorphism array).

SUMMARY

The use of preimplantation genetic diagnosis to assist the identification and preferential transfer of healthy euploid embryos should improve implantation rates, reduce miscarriages and trisomic offspring, and ultimately lead to an increase in live birth rates.

Quantitative decision-making in preimplantation genetic (aneuploidy) screening (PGS)

PURPOSE

To analyze using hypergeometric probability statistics the impact of performing preimplantation genetic screening (PGS) on a cohort of day 3 cleavage stage embryos.

METHODS

Statistical mathematical modeling.

RESULTS

We find the benefit of performing PGS is highly dependent on the number of day 3 embryos available for biopsy. Additional hidden variables that determine the outcome of PGS are the rates of aneuploidy and mosaicism, and the probability of a chromosomally mosaic embryo to test "normal". If PGS is performed, our analysis shows that many combinations of the number of biopsiable embryos, and the rates of aneuploidy and mosaicism results in a marginal benefit from the intervention. Other combinations are detrimental if PGS is actually undertaken. Finally, increases in PGS error rates lead to a rapid loss in the ability of PGS to provide useful discriminatory information.

CONCLUSION

We set out the statistical framework to determine the limits of PGS when a specific number of day 3 preimplantation embryos are available for biopsy. In general, PGS cannot be recommended a priori for a specific clinical situation due to the statistical uncertainties associated with the different hidden variable quantitative parameters considered important to the clinical outcome.

Association of p53 polymorphism with ICSI/IVF failure and recurrent pregnancy loss

BACKGROUND

The p53 tumour suppressor gene is a well-known factor regulating apoptosis in a wide variety of cells. Alterations in the p53 gene are among the most common genetic changes in human cancers. Several polymorphisms of the p53 tumour suppressor gene have been associated with recurrent pregnancy loss (RPL).

AIMS

To evaluate the association of polymorphisms p53 codon 72 with the response to in vitro fertilisation (IVF) treatment and occurrence of repeated miscarriages.

METHODS

The homozygous and heterozygous genotypes and allelic frequencies of Arg and Pro p53 at codon 72 were identified by using polymerase chain reaction-restriction fragment length polymorphism technique in 70 infertile women with more than two IVF failures. Each comparison was made with 97 women experiencing RPL and 32 fertile women each with at least two healthy children as the control group.

RESULTS

The frequency of homozygous Pro/Pro genotypes was found significantly higher among the women with RPL than the other two groups (P = 0.041). Whereas, Arg/Arg genotype was significantly different in the recurrent implantation failure (RIF) group (P = 0.005).

CONCLUSION

It is concluded that p53 codon 72 polymorphism may serve as a susceptible factor affecting the chances of RPL and RIF.

Approaches to improve the diagnosis and management of infertility

BACKGROUND Recent advances in our understanding of the causes of infertility and of assisted reproductive technology (ART) have led to the development of complex diagnostic tools, prognostic models and treatment options. The Third Evian Annual Reproduction (EVAR) Workshop Meeting was held on 26-27 April 2008 to evaluate evidence supporting current approaches to the diagnosis and management of infertility and to identify areas for future research efforts. METHODS Specialist reproductive medicine clinicians and scientists delivered presentations based on published literature and ongoing research on patient work-up, ovarian stimulation and embryo quality assessment during ART. This report is based on the expert presentations and subsequent group discussions and was supplemented with publications from literature searches and the authors' knowledge. RESULTS It was agreed that single embryo transfer (SET) should be used with increasing frequency in cycles of ART. Continued improvements in cryopreservation techniques, which improve pregnancy rates using supernumerary frozen embryos, are expected to augment the global uptake of SET. Adaptation and personalization of fertility therapy may help to optimize efficacy and safety outcomes for individual patients. Prognostic modelling and personalized management strategies based on individual patient characteristics may prove to represent real progress towards improved treatment. However, at present, there is limited good-quality evidence to support the use of these individualized approaches. CONCLUSIONS Greater quality control and standardization of clinical and laboratory evaluations are required to optimize ART practices and improve individual patient outcomes. Well-designed, good-quality studies are required to drive improvements to the diagnosis and management of ART processes.

Technology requirements for preimplantation genetic diagnosis to improve assisted reproduction outcomes

Preimplantation genetic diagnosis has been proposed as a method to improve assisted reproduction technology outcomes, but different techniques have produced conflicting results. The use of appropriate techniques may provide positive outcomes.

[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.

Preimplantation genetic screening for aneuploidy of embryos after in vitro fertilization in women aged at least 35 years: a prospective randomized trial

OBJECTIVE

To test the hypothesis that patients with advanced maternal age (AMA) have a higher implantation rate (IR) after embryo transfer of embryos with a normal chromosomal pattern for the chromosomes studied with preimplantation genetic screening (PGS) compared with patients who had an embryo transfer without PGS.

DESIGN

Prospective randomized controlled trial (RCT).

SETTING

Academic tertiary setting.

PATIENT(S)

Patients with AMA (> or =35 years).

INTERVENTION(S)

In an RCT, the clinical IR per embryo transferred was compared after embryo transfer on day 5 or 6 between the PGS group (analysis of chromosomes 13, 16, 18, 21, 22, X, and Y) and the Control group without PGS.

MAIN OUTCOME MEASURE(S)

No differences were observed between the PGS group and the Control group for the clinical IR (15.1%; 14.9%; rate ratio 1.01; exact confidence interval [CI], 0.25-5.27), the ongoing IR (at 12 weeks) (9.4%; 14.9%), and the live born rate per embryo transferred (9.4%; 14.9%; rate ratio 0.63; exact CI, 0.08-3.37). Fewer embryos were transferred in the PGS group (1.6 +/- 0.6) than in the Control group (2.0 +/- 0.6). A normal diploid status was observed in 30.3% of the embryos screened by PGS.

CONCLUSION(S)

In this RCT, the results did not confirm the hypothesis that PGS results in improved reproductive outcome in patients with AMA.

Preimplantation genetic screening: a survey of in vitro fertilization clinics

PURPOSE

The purpose of this study was to determine which US in vitro fertilization clinics provide preimplantation genetic screening for aneuploidy in treating infertility, and to explore clinic directors' attitudes toward this technique.

METHODS

Online survey included 415 US assisted reproductive technology clinics. The survey had a valid response rate of 45% or 186 clinics.

RESULTS

Nearly 68% of US in vitro fertilization clinics responding to the survey provided preimplantation genetic screening in an effort to increase success rates of fertility treatment. More than half of these in vitro fertilization clinics (56%) provided preimplantation genetic screening for advanced maternal age and the same percentage provided preimplantation genetic screening to treat repeated in vitro fertilization failure, whereas 66% provided preimplantation genetic screening to treat women with repeated miscarriage. Opinions of the effectiveness of preimplantation genetic screening for these indications varied widely, even among those providing it. Most directors (85%) of clinics providing preimplantation genetic screening believed that more data are needed to determine whether and to whom it should be offered.

CONCLUSIONS

Despite the lack of data supporting the use of preimplantation genetic screening for recurrent pregnancy loss, in vitro fertilization failure, and advanced maternal age, a majority of in vitro fertilization clinics in the United States offer preimplantation genetic screening for these purposes. There is significant support among clinic directors for more research into the effectiveness of preimplantation genetic screening and for professional guidelines in this area.

Use of comprehensive chromosomal screening for embryo assessment: microarrays and CGH

One of the most important factors influencing embryo viability is chromosome imbalance (aneuploidy). Embryos derived from aneuploid gametes have little potential for forming a viable pregnancy, but cannot be distinguished from normal embryos using standard morphological evaluation. For more than a decade, preimplantation genetic screening (PGS) has been used to assist in the identification of aneuploid embryos. However, current strategies, based upon cell biopsy followed by fluorescent in situhybridization, allow less than half of the chromosomes to be screened. In this review, we discuss methods that overcome the limitations of earlier PGS strategies and provide screening of the entire chromosome complement in oocytes and embryos. In recent months, there has been a rapid growth in the number of PGS cycles utilizing one such method, comparative genomic hybridization (CGH). Data from IVF cycles utilizing CGH must be considered preliminary, but appear to indicate a dramatic increase in embryo implantation following comprehensive chromosomal screening. It is expected that methods based upon microarrays will yield similar clinical results and may be sufficiently rapid to permit comprehensive screening without the need for embryo cryopreservation. Some microarray platforms also offer the advantage of embryo fingerprinting and the potential for combined aneuploidy and single gene disorder diagnosis. However, more data concerning accuracy and further reductions in the price of tests will be necessary before microarrays can be widely applied.

Preimplantation genetic screening does not improve delivery rate in women under the age of 36 following single-embryo transfer

BACKGROUND

Single-embryo transfer is a well-accepted strategy to avoid multiple pregnancies in an assisted reproductive technology (ART) programme. Besides the morphological quality and embryo kinetics up to the blastocyst stage, preimplantation genetic screening (PGS) of aneuploidy has been advocated as an adjuvant approach to select the embryo.

METHODS

Couples with a female partner younger than 36 were randomly assigned to undergo transfer of a single blastocyst in a cycle with or without PGS using FISH for the chromosomes X, Y, 13, 16, 18, 21, 22.

RESULTS

After the enrolment of 120 of the projected 447 patients in each group, study recruitment was terminated prematurely on the basis of futility. The observed live birth delivery rates after ART were 30.8 versus 30.8% per randomized patient, 34.6 versus 34.6% per cycle initiated, 37.8 versus 37.0% per aspirated cycle and 41.6 versus 43.5% per embryo transfer for the control versus the PGS group, respectively, with absolute between-group differences (95% CI; P value) of 0% (-11.7 to 11.7; P = 1.00), 0% (-12.7 to 12.7; P = 1.00), -0.8% (-14.2 to 12.7; P = 0.91) and 2.1% (-12.7 to 16.7; P = 0.79), respectively. Even in this younger age group, only 61% of the embryos had a normal diploid status.

CONCLUSIONS

The absence of a beneficial treatment effect in this randomized clinical trial provides no arguments in favour of PGS to improve live birth delivery rate following single-embryo transfer in women under the age 36. Clinical Trials.gov: NCT00670059.

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.

Preimplantation genetic screening in women of advanced maternal age caused a decrease in clinical pregnancy rate: a randomized controlled trial

BACKGROUND

Advanced maternal age (AMA) is an important parameter that negatively influences the clinical pregnancy rate in IVF, in particular owing to the increased embryo aneuploidy rate. It has thus been suggested that only transferring euploid embryos in this patient group would improve the pregnancy rate. The purpose of this study was to test whether employing preimplantation genetic screening (PGS) in AMA patients would increase the clinical pregnancy rate.

METHODS

We conducted a two-center, randomized controlled trial (RCT) to analyze the outcome of embryo transfers in AMA patients (>or=38 years of age) after PGS using FISH analysis for chromosomes X, Y, 13, 16, 18, 21 and 22. The PGS group was compared with a control group. The primary outcome measure was clinical pregnancy rate after 6-7 weeks of gestation per randomized patient.

RESULTS

The study was terminated early as an interim analysis showed a very low conditional power of superiority for the primary outcome. Of the 320 patients calculated to be included in the study, 56 and 53 patients were randomized into the PGS and control groups, respectively. The clinical pregnancy rate in the PGS group was 8.9% (95% CI, 2.9-19.6%) compared with 24.5% (95% CI, 13.8-38.3%) in the control group, giving a difference of 15.6% (95% CI, 1.8-29.4%, P = 0.039).

CONCLUSIONS

Although the study was terminated early, this RCT study provides evidence against the use of PGS for AMA patients when performing IVF.

TRIAL REGISTRATION NUMBER

ISRCTN38014610.

Single-cell DNA and FISH analysis for application to preimplantation genetic diagnosis

The goal of preimplantation genetic diagnosis (PGD) is to avoid transfer of embryos affected with a specific genetic disease or condition. This unit describes the steps involved in amplifying DNA from a single blastomere and specific assays for detecting a variety of DNA mutations. For some assays, whole-genome amplification by primer-extention preamplification (PEP) is performed prior to analysis. Support protocols describe the biopsy of one or two blastomeres from the developing preimplantation embryo, isolation for further investigation of all blastomeres from embryos shown to have the mutant allele, and isolation of single lymphocytes or lymphoblastoid cells as models for single-cell DNA analysis. A procedure for FISH analysis on single interphase blastomeres is provided along with a support protocol for probe validation that is recommended as a preliminary step before performing any PGD FISH analysis.

Dichorionic triamniotic triplet pregnancy with monozygotic twins discordant for trisomy 13 after preimplantation genetic screening: case report

OBJECTIVE

To report the first dichorionic triamniotic triplet pregnancy discordant for trisomy 13 after in vitro fertilization (IVF) treatment with preimplantation genetic screening (PGS).

DESIGN

Case report.

SETTING

Private IVF center.

PATIENT(S)

A 40-year-old para 1+6 woman.

INTERVENTION(S)

IVF combined with PGS for chromosomes 13, 16, 18, 21, and 22, resulting in the transfer of two embryos.

MAIN OUTCOME MEASURE(S)

Prenatal fetal ultrasonography revealed a dichorionic triamniotic triplet pregnancy. An amniocentesis, performed at 15-weeks' gestation, confirmed that the singleton and one monozygotic twin were normal but the other monozygotic twin was trisomy 13.

RESULT(S)

After diagnosis and counseling, selective termination of the trisomy 13 monozygotic twin was performed at 16 weeks and 4 days. At 18 weeks and 4 days the co-twin died. A healthy boy was delivered by elective caesarean section at 36-weeks' gestation.

CONCLUSION(S)

Assisted reproductive techniques that breach the embryo's zona pellucida such as assisted hatching and PGS embryo biopsy increase the incidence of monozygotic twins. Due to high levels of mosaicism in human preimplantation embryos, PGS cannot ensure that embryos diagnosed as normal and selected for transfer do not contain abnormal cells. Hence, further reports of discordant monozygotic twins following PGS are expected, emphasizing the need for appropriate counseling of patients wishing to embark on an IVF/PGS treatment cycle.

Preimplantation genetic screening: "established" and ready for prime time?

Unless attempts to improve pregnancy rates and/or diminish miscarriage rates through preimplantation genetic screening (PGS) are applied to only carefully selected patients, they will fail. Because specific PGS indications have remained undefined, PGS should be considered an experimental procedure.

Live birth following preimplantation genetic screening for trisomy 21. Should aneuploidy screening be offered to all older patients undergoing IVF?

A 42-year-old female patient with history of secondary infertility was referred to our assisted conception unit for in vitro fertilization (IVF). Before her referral, she had two cycles of IVF at another centre; the first was unsuccessful and, after conceiving at the second attempt, the pregnancy was terminated at 14 weeks' gestation following a positive nuchal translucency scan and a diagnosis of trisomy 21 (Down syndrome) by a chorionic villous biopsy performed in the first trimester. The screening tests for trisomy 21 were offered to the patient in view of her advanced age. Subsequent karyotyping revealed that both partners had a normal chromosomal complement. Following genetic counselling, the couple were offered IVF treatment along with preimplantation genetic screening for trisomy 21. Four of the five embryos were suitable for biopsy, and one blastomere from each embryo was analyzed using fluorescent in situ hybridization for chromosome 21. The analysis revealed that two embryos had trisomy 21, one had monosomy 21, and only one embryo was diploid for chromosome 21. The single diploid embryo was transferred to the uterus on day 3, and resulted in an uneventful pregnancy and delivery of a healthy live-born male.

Preimplantation genetic screening in older women: a cost-effectiveness analysis

OBJECTIVE

To compare the strategy of traditional IVF with prenatal diagnosis versus IVF with preimplantation genetic screening (IVF/PGS) to prevent aneuploid births in women with advanced maternal age.

DESIGN

A decision tree analytic model was created to compare IVF alone versus IVF/PGS to evaluate which strategy is the least costly per healthy (euploid) infant.

SETTING

Outpatient IVF practices.

PATIENT(S)

Infertile women, 38-40 and >40 years old.

INTERVENTION(S)

IVF or IVF/PGS.

MAIN OUTCOME MEASURE(S)

Cost per healthy infant.

RESULT(S)

Using base-case estimates of costs and probabilities in women aged 38-40 years, after a maximum of two fresh IVF cycles and two frozen cycles, the chance of having a healthy infant was 37.8% with IVF alone versus 21.7% with IVF/PGS. The average cost for each strategy is $25,700, but the cost per healthy infant is substantially higher when IVF/PGS is applied as opposed to IVF alone ($118,713 vs. $68,026). To assess the robustness of the model, all probabilities were varied simultaneously in a Monte Carlo simulation, and in 96.2% of trials, IVF alone proved to be the most cost-effective option. Conversely, our data demonstrate that in women aged >40, IVF and IVF/PGS are essentially equal in terms of cost-effectiveness ($122,000 vs. $118,713).

CONCLUSION(S)

IVF alone is less costly per healthy infant than IVF/PGS in women ages 38-40.

Patient willingness to participate in a clinical trial with preimplantation genetic diagnosis

OBJECTIVE

To investigate patients' interest in preimplantation genetic diagnosis (PGD) as a method for aneuploidy screening and their willingness to participate in a clinical trial using PGD.

DESIGN

Anonymous questionnaire.

SETTING

University infertility clinic.

PATIENT(S)

Women seeking treatment for infertility at the study clinic.

INTERVENTION(S)

Subjects completed a two-part structured questionnaire. The questionnaire included demographic and fertility history questions, followed by opinion questions on testing for genetic diseases. The second portion of the questionnaire included opinion questions about willingness to use PGD and to participate in a clinical trial using PGD after reading a document explaining PGD.

MAIN OUTCOME MEASURE(S)

Patients' interest in using PGD and willingness to participate in a clinical trial involving PGD.

RESULT(S)

Before reading a description of PGD, 84% of participants indicated that they were interested in having their embryos tested. The majority (86%) remained interested in testing their embryos with PGD after reading the informational paragraph. Most (91%) of the women who remained interested in PGD also indicated a willingness to participate in a clinical trial involving PGD. Of the patients who initially were not interested in testing their embryos, nearly half of them (47%) indicated an interest in PGD after reading the informational paragraph, and nearly all of those who changed their mind were willing to be in a trial.

CONCLUSION(S)

Many women undergoing IVF are interested in the possibility of utilizing PGD for aneuploidy screening. Better evidence is needed regarding outcomes using PGD for this indication before it can be routinely incorporated into practice. A clinical trial using PGD in this setting appears possible because a majority of the patients, in this survey, would be willing to participate.

Molecular methods for selection of the ideal oocyte

Some recent strategies for identifying the ideal oocyte for insemination in assisted reproduction techniques are reviewed. Established methods of assessing the female gamete, such as morphological evaluation of oocytes and cytogenetic analysis of polar bodies using fluorescence in-situ hybridization, will soon be joined by more advanced cytogenetic methods such as the use of comparative genomic hybridization to improve understanding of oocyte genetics. It seems likely, however, that the greatest advances will originate from the evolution of molecular genetic technologies. The application of microarray technology to individual oocytes and their associated cumulus cells has recently been accomplished, providing a simultaneous assessment of activity for thousands of genes and revealing potential viability markers. Furthermore, improved equipment and optimized methods of mass spectrometry have provided sufficient sensitivity to allow proteomic profiles to be generated from single oocytes and embryos, while metabolomic investigations have searched for indicators of oocyte/embryo quality in spent culture medium. Techniques of this type may ultimately lead to non-invasive tests for oocyte quality revealing previously hidden information concerning both oocyte and embryo developmental competence. Once fully validated, these new approaches are expected to revolutionize oocyte and embryo selection, leading to improved implantation rates and higher probabilities of success using elective single embryo transfer.

Selection of embryos by morphology is less effective than by a combination of aneuploidy testing and morphology observations

There is a known correlation between morphology and euploidy, but we believe that the association between the two embryo selection systems is too marginal to claim that it is absolute and that one can simply replace one system by the other. The optimal way to select euploid embryos is through a combination of morphology determination and preimplantation genetic diagnosis.

Ten-year experience with preimplantation genetic diagnosis (PGD) at the New York University School of Medicine Fertility Center

We describe our experience of over 300 cycles of preimplantation genetic diagnosis (PGD) and report clinical pregnancy rates (35%-67%) that support using this technology to screen for genetic disorders and chromosomal abnormalities. In clinical practice for over ten years, PGD offers couples the earliest form of genetic screening and may help improve ongoing pregnancy rates in poor-prognosis patients.