Three hundred and thirty cycles of preimplantation genetic diagnosis for serious genetic disease: clinical considerations affecting outcome

Charcot-Marie-Tooth disease: from historical landmarks in Brazil to current care perspectives

Hereditary motor and sensory neuropathy, also known as Charcot-Marie-Tooth disease (CMT), traditionally refers to a group of genetic disorders in which neuropathy is the main or sole feature. Its prevalence varies according to different populations studied, with an estimate between 1:2,500 to 1:10,000. Since the identification of PMP22 gene duplication on chromosome 17 by Vance et al., in 1989, more than 100 genes have been related to this group of disorders, and we have seen advances in the care of patients, with identification of associated conditions and better supportive treatments, including clinical and surgical interventions. Also, with discoveries in the field of genetics, including RNA interference and gene editing techniques, new treatment perspectives begin to emerge. In the present work, we report the most import landmarks regarding CMT research in Brazil and provide a comprehensive review on topics such as frequency of different genes associated with CMT in our population, prevalence of pain, impact on pregnancy, respiratory features, and development of new therapies.

A practical approach to the genomics of kidney disorders

Rapid technological advances in genomic testing continue to increase our understanding of the genetic basis of a wide range of kidney disorders. Establishing a molecular diagnosis benefits the individual by bringing an end to what is often a protracted diagnostic odyssey, facilitates accurate reproductive counselling for families and, in the future, is likely to lead to the delivery of more targeted management and surveillance regimens. The selection of the most appropriate testing modality requires an understanding both of the technologies available and of the genetic architecture and heterogeneity of kidney disease. Whilst we are witnessing a far greater diagnostic yield with broader genetic testing, such approaches invariably generate variants of uncertain significance and secondary incidental findings, which are not only difficult to interpret but present ethical challenges with reporting and feeding back to patients and their families. Here, we review the spectrum of nephrogenetic disorders, consider the optimal approach to genetic testing, explore the clinical utility of obtaining a molecular diagnosis, reflect on the challenges of variant interpretation and look to the future of this dynamic field.

Review: Preimplantation genetic diagnosis (PGD) as a reproductive option in patients with neurodegenerative disorders

Preimplantation genetic diagnosis (PGD) was introduced in the late 1980s and represents an option for couples at risk of transmitting an inherited, debilitating or neurological disorder to their children. From a cleavage or blastocyst stage embryo, cell(s) are collected and then genetically analyzed for disease; enabling an unaffected embryo to be transferred into the uterus cavity. Nowadays, PGD has been carried out for several hundreds of heritable conditions including myotonic dystrophy, and for susceptibility genes involved in cancers of the nervous system. Currently, advanced molecular technologies with better resolution, such as array comparative genomic hybridisation, quantitative polymerase chain reaction, and next generation sequencing, are on the verge of becoming the gold standard in embryo preimplantation screening. Given this, it may be time for neurological societies to consider the published evidence to develop new guidelines for the integration of PGD into modern preventative neurology. Therefore, the main aim of this review is to illustrate the option of PGD to enable conception of an unaffected baby, and to assist clinicians and neurologists in the counseling of the patient at risk of transmitting an inherited disease, to explore the genetic journey throughout in vitro fertilization IVF with PGD.

Cumulative outcome of pre-implantation genetic diagnosis for sickle cell disease: a 5-year review

To review the cumulative outcome of pre-implantation genetic diagnosis (PGD) cycles performed for prevention of sickle cell disease (SCD). Couples referred for PGD for SCD between April 2012 and October 2017 were included. Ovarian stimulation was performed using a short gonadotrophin-releasing hormone (GnRH) antagonist protocol and follicle-stimulating hormone injections. The GnRH agonist was used to trigger oocyte maturation. Oocytes were fertilised using intracytoplasmic sperm injection. Trophectoderm biopsy was performed on day 5 or 6 followed by vitrification. Genetic testing was done using pre-implantation genetic haplotyping. A total of 60 couples started 70 fresh PGD cycles (mean 1·2 cycles/couple) and underwent a total of 74 frozen-embryo-transfer (FET) cycles (mean 1·3 FET/couple). The mean (SD) female age was 33 (4·4) years and the mean (SD) anti-müllerian hormone level was 22·9 (2·8) pmol/l. The cumulative live-birth rate was 54%/PGD cycle started and 63%/couple embarking on PGD. The rate of multiple births was 8%. The cumulative outcome of PGD treatment for prevention of SCD transmission is high and PGD treatment should be offered to all at-risk couples.

Utility and First Clinical Application of Screening Embryos for Polygenic Disease Risk Reduction

For over 2 decades preimplantation genetic testing (PGT) has been in clinical use to reduce the risk of miscarriage and genetic disease in patients with advanced maternal age and risk of transmitting disease. Recently developed methods of genome-wide genotyping and machine learning algorithms now offer the ability to genotype embryos for polygenic disease risk with accuracy equivalent to adults. In addition, contemporary studies on adults indicate the ability to predict polygenic disorders with risk equivalent to monogenic disorders. Existing biobanks provide opportunities to model the clinical utility of polygenic disease risk reduction among sibling adults. Here, we provide a mathematical model for the use of embryo screening to reduce the risk of type 1 diabetes. Results indicate a 45-72% reduced risk with blinded genetic selection of one sibling. The first clinical case of polygenic risk scoring in human preimplantation embryos from patients with a family history of complex disease is reported. In addition to these data, several common and accepted practices place PGT for polygenic disease risk in the applicable context of contemporary reproductive medicine. In addition, prediction of risk for PCOS, endometriosis, and aneuploidy are of particular interest and relevance to patients with infertility and represent an important focus of future research on polygenic risk scoring in embryos.

Oocyte cryopreservation for women with GATA2 deficiency

PURPOSE

To describe controlled ovarian stimulation (COS) in a population of women with GATA2 deficiency, a genetic bone marrow failure syndrome, prior to allogeneic hematopoietic stem cell transplant METHODS: This is a retrospective case series of nine women with GATA2 deficiency who underwent oocyte preservation at a research institution. Main outcomes measured include baseline fertility characteristics ((antimullerian hormone (AMH) and day 3 follicle-stimulating hormone (FSH) and estradiol (E2)) and total doses of FSH and human menopausal gonadotropins (HMG), E2 on day of trigger, and total number of metaphase II oocytes retrieved.

RESULTS

The mean age was 24 years [16-32], mean AMH was 5.2 ng/mL [0.7-10], and day 3 mean FSH was 5.1 U/L [0.7-8.1], and E2 was 31.5 pg/mL [< 5-45]. The mean dose of FSH was 1774 IU [675-4035], and HMG was 1412 IU [375-2925] with a mean E2 of 2267 pg/mL [60.7-4030] on day of trigger. The mean total of metaphase II oocytes was 7.7 [0-15]. One patient was diagnosed with a deep vein thrombosis (DVT) with pulmonary embolism (PE) during COS.

CONCLUSION

This study is the first to analyze the outcomes of COS in women with GATA2 deficiency. The response to ovarian stimulation suggests that oocyte cryopreservation should be considered prior to gonadotoxic therapy. However, due to the risk of potentially life-threatening complications, it is prudent that patients are properly counseled of the risks and are evaluated by a multi-disciplinary medical team prior to COS.

Embryo pooling: a promising strategy for managing insufficient number of embryos in preimplantation genetic diagnosis

This retrospective study evaluated the embryo pooling strategy for managing insufficient number of embryos in preimplantation genetic diagnosis (PGD) through serial vitrification of cleavage-stage embryos from consecutive cycles, and simultaneous blastocysts biopsy in combination with blastocysts obtained in ultimate fresh cycle. A retrospective analysis of the cumulative pregnancy rate of 68 patients underwent cleavage-stage embryos accumulation (Embryo Pooling Group) and 94 patients underwent one stimulation cycle (Control Group) over a 2-year period were conducted. The blastocyst formation rate was comparable between the consecutive cycles and the ultimate cycle in embryo pooling group (56.0 versus 62.0%, p = .078). No significant difference existed between twice-vitrified and once-vitrified warmed blastocysts with respect to implantation rate (50.8 versus 46.3%, p = .658). The implantation rate and cumulative pregnancy rate of embryo pooling group were 49.0 and 67.6%, respectively, which were statistically comparable to the corresponding values of 48.9 and 73.4% obtained in control group. Our study suggests that in patients undergoing ICSI-PGD who do not reach enough embryos in a single stimulation cycle, pooling embryos from consecutive ovarian stimulation cycles is a promising strategy, which can render a cumulative pregnancy rate comparable to those patients who only require one stimulation cycle.

Preliminary trials of a specific gravity technique in the determination of early embryo growth potential†

STUDY QUESTION

Can a modified specific gravity technique be used to distinguish viable from nonviable embryos?

SUMMARY ANSWER

Preliminary data suggests a modified specific gravity technique can be used to determine embryo viability and potential for future development.

WHAT IS KNOWN ALREADY

Single embryo transfer (SET) is fast becoming the standard of practice. However, there is currently no reliable method to ensure development of the embryo transferred.

STUDY DESIGN, SIZE, DURATION

A preliminary, animal-based in vitro study of specific gravity as a predictor of embryo development using a mouse model.

PARTICIPANTS/MATERIALS, SETTING, METHODS

After a brief study to demonstrate embryo recovery, experiments were conducted to assess the ability of the specific gravity system (SGS) to distinguish between viable and nonviable embryos. In the first study, 1-cell mouse embryos were exposed to the SGS with or without previous exposure to an extreme heat source (60°C); measurements were repeated daily for 5 days. In the second experiment, larger pools of 1-cell embryos were either placed directly in culture or passed through the SGS and then placed in culture and monitored for 4 days.

MAIN RESULTS AND THE ROLE OF CHANCE

In the first experiment, viable embryos demonstrated a predictable pattern of descent time over the first 48 h of development (similar to previous experience with the SGS), while embryos that were heat killed demonstrated significantly altered drop patterns (P < 0.001); first descending faster. In the second experiment, average descent times were different for embryos that stalled early versus those that developed to blastocyst (P < 0.001). Interestingly, more embryos dropped through the SGS developed to blastocyst than the culture control (P < 0.01).

LIMITATIONS, REASONS FOR CAUTION

As this is a preliminary report of the SGS technology determining viability, a larger embryo population will be needed. Further, the current in vitro study will need to be followed by fecundity studies prior to application to a human population.

WIDER IMPLICATIONS OF THE FINDINGS

If proven, the SGS would provide a noninvasive means of assessing embryos prior to transfer after assisted reproductive technologies procedures, thereby improving fecundity and allowing more reliable SET.

STUDY FUNDING/COMPETING INTERESTS

The authors gratefully acknowledge the funding support of the U.S. Jersey Association, the Laura W. Bush Institute for Women's Health and a Howard Hughes Medical Institute grant through the Undergraduate Science Education Program to Texas Tech University. None of the authors have any conflict of interest regarding this work.

TRIAL REGISTRATION NUMBER

none.

Current status of preimplantation genetic diagnosis in Japan

This is a retrospective study aimingto clarify the current status of preimplantation genetic diagnosis (PGD) in Japan. Our data were collected from 12 facilities between September 2004 and September 2012, and entered into a database. A majority of PGD in Japan was performed for balanced structural chromosomal abnormalities in couples with recurrent miscarriage. PGD for monogenic diseases was performed only in two facilities. The average maternal age was 38 years for monogenic diseases and 40 years for chromosomal abnormalities. Overall there have been671 cycles to oocyte retrieval reported. Of these cycles, 85% (572 cycles)were for chromosomal abnormalities, and 15% (99 cycles) for monogenic diseases. Diagnosis rates in the current study were 70.8% for monogenic diseases and 94.0% for chromosomal abnormalities. Rates of embryo transfer of PGD were 62.7% for monogenic diseases and 25.5% for chromosomal abnormalities. Clinical pregnancy rates per embryo transfer were 12.0% for monogenic diseases and 35.6% for chromosomal abnormalities. Our study is the first PGD report from all facilities which had the approval of the ethics committee of the Japanese Society of Obstetrics and Gynecology. We have built a basis for gathering continuous PGD data in Japan.

Preimplantation genetic diagnosis for inherited neurological disorders

Preimplantation genetic diagnosis (PGD) is an option for couples at risk of having offspring with an inherited debilitating or fatal neurological disorder who wish to conceive a healthy child. PGD has been carried out for conditions with various modes of inheritance, including spinal muscular atrophy, Huntington disease, fragile X syndrome, and chromosomal or mitochondrial disorders, and for susceptibility genes for cancers with nervous system involvement. Most couples at risk of transmitting a genetic mutation would opt for PGD over prenatal testing and possible termination of a pregnancy. The aim of this Perspectives article is to assist neurologists in counselling and treating patients who wish to explore the option of PGD to enable conception of an unaffected child. PGD can be accomplished for most disorders in which the genetic basis is known, and we argue that it is time for clinicians and neurological societies to consider the evidence and to formulate guidelines for the responsible integration of PGD into modern preventative neurology.

Preimplantation genetic diagnosis for Charcot-Marie-Tooth disease

Objective

Preimplantation genetic diagnosis (PGD) is an assisted reproductive technique for couples carrying genetic risks. Charcot-Marie-Tooth (CMT) disease is the most common hereditary neuropathy, with a prevalence rate of 1/2,500. In this study, we report on our experience with PGD cycles performed for CMT types 1A and 2F.

Methods

Before clinical PGD, we assessed the amplification rate and allele drop-out (ADO) rate of multiplex fluorescent polymerase chain reaction (PCR) followed by fragment analysis or sequencing using single lymphocytes. We performed six cycles of PGD for CMT1A and one cycle for CMT2F.

Results

Two duplex and two triplex protocols were developed according to the available markers for each CMT1A couple. Depending on the PCR protocols, the amplification rates and ADO rates ranged from 90.0% to 98.3% and 0.0% to 11.1%, respectively. For CMT2F, the amplification rates and ADO rates were 93.3% and 4.8%, respectively. In case of CMT1A, 60 out of 63 embryos (95.2%) were diagnosed and 13 out of 21 unaffected embryos were transferred in five cycles. Two pregnancies were achieved and three babies were delivered without any complications. In the case of CMT2F, a total of eight embryos were analyzed and diagnosed. Seven embryos were diagnosed as unaffected and four embryos were transferred, resulting in a twin pregnancy. Two healthy babies were delivered.

Conclusion

This is the first report of successful pregnancy and delivery after specific PGD for CMT disease in Korea. Our PGD procedure could provide healthy babies to couples with a high risk of transmitting genetic diseases.

Multiple displacement amplification for preimplantation genetic diagnosis of fragile X syndrome

Preimplantation genetic diagnosis (PGD) has become an assisted reproductive technique for couples that have genetic risks. Despite the many advantages provided by PGD, there are several problems, including amplification failure, allele drop-out and amplification inefficiency. We evaluated multiple displacement amplification (MDA) for PGD of the fragile X syndrome. Whole genome amplification was performed using MDA. MDA products were subjected to fluorescent PCR of fragile X mental retardation-1 (FMR1) CGG repeats, amelogenin and two polymorphic markers. In the pre-clinical tests, the amplification rates of the FMR1 CGG repeat, DXS1215 and FRAXAC1 were 84.2, 87.5 and 75.0%, respectively, while the allele dropout rates were 31.3, 57.1 and 50.0%, respectively. In two PGD treatment cycles, 20 embryos among 30 embryos were successfully diagnosed as 10 normal embryos, four mutated embryos and six heterozygous carriers. Three healthy embryos were transferred to the uterus; however, no clinical pregnancy was achieved. Our data indicate that MDA and fluorescent PCR with four loci can be successfully applied to PGD for fragile X syndrome. Advanced methods for amplification of minuscule amounts of DNA could improve the sensitivity and reliability of PGD for complicated single gene disorders.

Outcomes of ovarian stimulation in a two-day oocyte collection week with PGD cycles compared to a five-day oocyte collection week with conventional IVF/ICSI cycles

We assessed the outcomes of ovarian stimulation in a two-day egg collection (EC) week with preimplantation genetic diagnosis (PGD) cycles (N = 307) compared to a five-day EC week with conventional in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles (N = 2,417). The mean (SD) age of women undergoing PGD was 34 (3.97) and 35 (3.85) for IVF/ICSI (P < 0.001), the number of oocytes collected was 13 (7.37) and 11 (7.02), (P < 0.001), while the mean (SD) number of fertilized oocytes was 8 (5.09) and 6 (4.58), respectively (P < 0.001). The clinical pregnancy rate per embryo transfer (ET) was 37% with PGD and 38% with IVF/ICSI (P = 0.49), while the implantation rate was 0.35 and 0.30, respectively (P = 0.05). After adjusting for age and confounding variables including the number of oocytes collected and fertilized normally, the mode of treatment (PGD or IVF/ICSI) had no effect on clinical pregnancy (P = 0.48). In conclusion, scheduling of PGD cycles to a two-day EC week did not compromise the outcomes of ovarian stimulation when compared to a five-day EC week with conventional IVF/ICSI cycles. This can allow the provision of a more patient friendly service, increase the flexibility of satellite PGD services, and facilitate cycle programming with the genetics team providing PGD.

Conceptualizing couples' decision making in PGD: emerging cognitive, emotional, and moral dimensions

OBJECTIVE

To illuminate and synthesize what is known about the underlying decision making processes surrounding couples' preimplantation genetic diagnosis (PGD) use or disuse and to formulate an initial conceptual framework that can guide future research and practice.

METHODS

This systematic review targeted empirical studies published in English from 1990 to 2008 that examined the decision making process of couples or individual partners that had used, were eligible for, or had contemplated PGD. Sixteen studies met the eligibility requirements. To provide a more comprehensive review, empirical studies that examined healthcare professionals' perceptions of couples' decision making surrounding PGD use and key publications from a variety of disciplines supplemented the analysis.

RESULTS

The conceptual framework formulated from the review demonstrates that couples' PGD decision making is composed of three iterative and dynamic dimensions: cognitive appraisals, emotional responses, and moral judgments.

CONCLUSION

Couples think critically about uncertain and probabilistic information, grapple with conflicting emotions, and incorporate moral perspectives into their decision making about whether or not to use PGD.

PRACTICE IMPLICATIONS

The quality of care and decisional support for couples who are contemplating PGD use can be improved by incorporating focused questions and discussion from each of the dimensions into counseling sessions.

Development and successful clinical application of preimplantation genetic haplotyping for Herlitz junctional epidermolysis bullosa

BACKGROUND

Herlitz junctional epidermolysis bullosa (HJEB) is a severe, life-threatening, autosomal recessive blistering skin disease for which no cure is currently available. Prenatal diagnosis for couples at risk is feasible through fetal skin biopsy or analysis of DNA extracted from chorionic villi, but these methods can be applied only after pregnancy has been established. An alternative approach, which involves the analysis of single cells from embryos prior to establishment of pregnancy, is preimplantation genetic diagnosis (PGD). Until now, its clinical uptake has been hindered by lengthy delays in establishing mutation-specific protocols, and by the small amount of template DNA that can be obtained from a single cell. A new method that addresses these problems, preimplantation genetic haplotyping (PGH), relies on whole genome amplification followed by haplotyping of multiple polymorphic markers using standard DNA-based polymerase chain reaction (PCR) assays.

OBJECTIVES

To design and validate a generic PGH assay for HJEB and to transfer this into clinical practice.

MATERIALS AND METHODS

We established a multiplex PCR-based PGH assay involving 16 markers within and flanking the LAMB3 gene (the most frequently mutated gene in HJEB). The assay was then validated in 10 families with at least one previously affected offspring. After licensing by the Human Fertilisation and Embryology Authority (HFEA), the new test was used for PGD in a couple at risk of HJEB.

RESULTS

The chromosome 1 LAMB3 markers within the assay were shown to be of sufficient heterogeneity to have widespread application for preimplantation testing of HJEB. In one couple that were heterozygous carriers of nonsense mutations in LAMB3, we used the new assay to identify unaffected embryos in a series of PGD cycles. Pregnancy was established in the third PGD cycle and a healthy, unaffected child was born. DNA analysis of cord blood confirmed the predicted single-cell mutation status of wild-type LAMB3 alleles.

CONCLUSIONS

PGH represents a major step forward in widening the scope and availability of preimplantation testing for serious mapped single-gene disorders. We have established a generic test that is suitable for the majority of couples at risk of HJEB.

Preimplantation genetic diagnosis for haematologic conditions

PURPOSE OF REVIEW

This review will inform the clinician about the application, success rates and limitations of preimplantation genetic diagnosis (PGD) for haematologic disease to enable clinicians to offer couples with reproductive risk a realistic view of possible treatments. The molecular techniques used to diagnose disease mutations are described, including the newest technologies using whole genome amplification (WGA) and preimplantation genetic haplotyping (PGH) of embryos. The history and ethics involved in performing PGD together with human leukocyte antigen (HLA) testing (PGD-H) to create matched siblings suitable for haematopoietic stem cell transplant (HSCT) are discussed.

RECENT FINDINGS

The greatest diagnostic hurdle in PGD is the paucity of molecular material in the single embryonic cell. WGA allows amplification of the entire genome, which greatly simplifies mutation analysis and increases the possibilities of multiple simultaneous genetic diagnoses. PGH can be applied to the amplified material, and may enable the application of PGD to the less common haematological mutations, and the diagnosis of nonaffected male progeny in cases of X-linked haematologic diseases.

SUMMARY

PGD to exclude embryos carrying serious haematologic disease is a viable alternative to prenatal diagnosis for couples who wish to avoid having affected children and for whom therapeutic termination of affected pregnancies is unacceptable. PGD is not available for all haematologic mutations, is expensive, time consuming and does not guarantee a pregnancy. PGD-H is more diagnostically and ethically challenging, especially when there is the time constraint of urgent provision of HLA-matched stem cells for a sick sibling. To date there is only a handful of reported cases of successful HSCT from siblings created by embryo selection. The evolving technology of PGH following WGA may increase the diagnostic scope and availability of PGD in the future, but certain limitations will remain.

Preimplantation genetic diagnosis for the prevention of sickle cell disease: current trends and barriers to uptake in a London teaching hospital

INTRODUCTION

Sickle cell disease (SCD) is a clinically significant hemoglobinopathy with increasing global incidence. We describe our experience of using pre-implantation genetic diagnosis (PGD) for the prevention of SCD at a tertiary referral centre in London.

METHODS

Between January 2002 and December 2007, of 78 at-risk couples referred for PGD treatment, 12 couples (15%) underwent 16 PGD cycles for the prevention of SCD. RESULTS. The live birth rate was 13% per initiated cycle, 18% per embryo transfer and 17% per couple.

CONCLUSIONS

Although PGD for prevention of the birth of a child affected by SCD is a viable treatment option for couples at risk of having an affected child, potential barriers to uptake of this service need to be fully addressed to ensure its availability to all couples seeking to avoid having a child affected with SCD.

Preimplantation genetic haplotyping: 127 diagnostic cycles demonstrating a robust, efficient alternative to direct mutation testing on single cells

Preimplantation genetic diagnosis using whole genome amplification and a haplotyping approach (PGH) was first described in 2006 and suggested as an efficient alternative to single-cell PCR for monogenic disorders. DNA from single cells was amplified using multiple displacement amplification; the resulting products were then tested using disease-specific PCR multiplexes applied under standard laboratory conditions to determine the haplotypes in the embryo. This study reports on a total of 127 completed biopsy cycles for 101 couples at risk of: autosomal recessive disease (71 cycles, 53 couples including one germ-line mosaic carrier), autosomal dominant disease (31 cycles, 26 couples including one germ-line mosaic carrier), X-linked recessive disease (18 cycles, 16 couples including one germ-line mosaic carrier), X-linked dominant disease (six cycles, five couples) and a double inheritance of both autosomal and X-linked recessive diseases (one cycle, one couple). Of these, 107 cycles reached embryo transfer. Overall success rates were: fetal heart beat-positive pregnancies (FHB+)/biopsy cycle=28%; FHB+/embryo transfer=34%; FHB+/couple=36%; 26 babies born, 13 ongoing pregnancies. These data demonstrate that PGH provides a robust, efficient and successful alternative to single-cell PCR for monogenic diseases.

A cost-benefit analysis of preimplantation genetic diagnosis for carrier couples of cystic fibrosis

OBJECTIVE

To perform a cost-benefit analysis of preimplantation genetic diagnosis (PGD) for carrier couples of cystic fibrosis (CF) compared with the alternative of natural conception (NC) followed by prenatal testing and termination of affected pregnancies.

DESIGN

Cost-benefit analysis using a decision analytic model.

SETTING

Outpatient reproductive health practices.

PATIENT(S)

A simulated cohort of 1,000 female patients.

INTERVENTION(S)

We calculated the net benefit of giving birth to a child as the present value of lifetime earnings minus lifetime medical costs.

MAIN OUTCOME MEASURE(S)

Net benefits in dollars.

RESULT(S)

When used for women younger than 35 years of age, the net benefit of PGD over NC was $182,000 ($715,000 vs. $532,000, respectively). For women aged 35-40 years, the net benefit of PGD over NC was $114,000 ($634,000 vs. $520,000, respectively). For women older than 40 years, however, the net benefit of PGD over NC was -$148,000 ($302,000 vs. $450,000, respectively).

CONCLUSION(S)

Preimplantation genetic diagnosis provides net economic benefits when used by carrier couples of CF. Although there is an upper limit of maternal age at which economic benefit can be demonstrated, carrier couples of CF should be offered PGD for prevention of an affected child.

Preimplantation genetic diagnosis as a source of human embryonic stem cells for disease research and drug discovery

Embryos surplus to therapeutic requirements following preimplantation genetic diagnosis can be used to derive human embryonic stem cell (hESC) lines carrying mutations significant to human disease. These cells provide a powerful in vitro tool for modelling disease progression in a number of cell types as well as having the potential to revolutionise drug discovery. Robust and reproducible directed differentiation protocols are needed to maximise the potential of these cells. In this review, we explore the current use of hESC and induced pluripotent stem cells in disease-specific research and discuss the use of stem cell technology in drug discovery and toxicity testing.

Estimation of chromosomal imbalances in preimplantation embryos from preimplantation genetic diagnosis cycles of reciprocal translocations with or without acrocentric chromosomes

OBJECTIVE

To estimate chromosomal imbalances in preimplantation embryos from reciprocal translocation carriers with or without acrocentric chromosomes (Acro-Ch) 13, 14, 15, 21, and 22 in preimplantation genetic diagnosis (PGD) cycles.

DESIGN

Fluorescence in situ hybridization was applied to PGD cycles for reciprocal translocation carriers.

SETTING

University-based centers for reproductive medicine.

PATIENT(S)

Ten and 24 patients of reciprocal translocation with and without Acro-Ch, respectively.

INTERVENTION(S)

Fluorescence in situ hybridization in biopsied blastomeres.

MAIN OUTCOME MEASURE(S)

Estimation of meiotic segregation mode in embryos from translocation carriers.

RESULT(S)

The proportion of alternative segregation for normal or balanced chromosome contents in preimplantation embryos from PGD cycles in reciprocal translocations without Acro-Ch was significantly higher than that with Acro-Ch (26.0% vs. 14.6%). The proportion of interchange trisomy in 3:1 segregation was significantly lower in reciprocal translocations without Acro-Ch than that with Acro-Ch (4.3% vs. 9.5%).

CONCLUSION(S)

This is the first report that the incidence of alternative segregation producing normal or balanced embryos was relatively low in reciprocal translocations associated with Acro-Ch. Our data may be useful to predict the possibility of normal or balanced embryos and to counsel with reciprocal translocation carriers for PGD-fluorescence in situ hybridization cycles.

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.

Use and misuse of preimplantation genetic testing

Detection of genetic diseases before implantation for couples at risk helps ensure healthy children, but testing for aneuploidy does not improve the chances of live birth in normal infertile women, say Peter Braude and Frances Flinter

Intracytoplasmic sperm injection (ICSI) in 2006: Evidence and Evolution

The introduction of intracytoplasmic sperm injection (ICSI) in 1992 has dramatically changed the management of severe male infertility. In severe male infertility, live birth rates with ICSI are superior to those with other non-donor treatments. In non-male infertility, however, pregnancy rates are not better with ICSI than with in vitro fertilization (IVF). With obstructive or non-obstructive azoospermia, reasonable pregnancy rates are now possible with ICSI after recovery of sperm from the testes followed by ICSI. Genetic counselling is indicated for severe male infertility, whether or not ICSI is considered. ICSI is indicated in preimplantation genetic diagnosis (PGD) to avoid contamination by extraneous DNA in the case of PCR-based testing and to increase the number of embryos available for testing. In turn, PGD may be indicated in pregnancies that are at high risk of aneuploidy because of genetic factors associated with azoospermia. As with IVF, not all couples succeed, but 2% of couples with failed ICSI cycles will conceive without treatment. ICSI outcome studies indicate that there is a significant increase in prematurity, low birthweight, and perinatal mortality associated with single and multiple births, similar to the outcomes of conventional IVF. However, as evidenced in long-term follow-up studies, the higher rates of urogenital abnormalities and increased use of healthcare may be associated with paternal characteristics.