Child health after preimplantation genetic testing.

RESEARCH QUESTION: Despite the increasing use of preimplantation genetic testing (PGT) for aneuploidy and monogenic diseases, for children conceived using PGT there is limited follow-up beyond 2 years of age. This study examined the health, well-being and development of school-aged children (5-8 years old) conceived following PGT. DESIGN: Retrospective cohort study of children conceived after IVF with PGT (exposed cohort) and children conceived after IVF without PGT (unexposed cohort) at two IVF clinics in Melbourne, born between 2000 and 2008, recruited with a 1:2 ratio. Mothers of the children completed a questionnaire asking child-specific questions regarding health and well-being, mental health, development, educational achievement and family-specific questions regarding family functioning and parent-child attachment. RESULTS: A total of 155 participants were recruited to the PGT cohort and 303 participants to the IVF-only cohort. There were no differences between the two cohorts with regards to maternal characteristics, birth defect frequency and pregnancy characteristics, apart from delivery by Caesarean section, which was more frequent in PGT singletons (55%) compared with IVF-only singletons (36%). While no significant differences between the PGT and IVF-only cohorts were found for the majority of general health and psychological scales, there were differences when compared with population data. Children in the exposed cohort appeared to have more positive outcomes in many of the measures. CONCLUSION: The data from this study suggest that PGT does not cause adverse outcomes in children. However, the nature (self-report) and small sample size of the study must be taken into consideration when interpreting the data.

Assisted reproductive technology (ART) cumulative live birth rates following preimplantation genetic diagnosis for aneuploidy (PGD-A) or morphological assessment of embryos: A cohort analysis.

BACKGROUND: Preimplantation genetic diagnosis for aneuploidy (PGD-A) for all 24 chromosomes improves implantation and clinical pregnancy rates per single assisted reproductive technology (ART) cycle. However, there is limited data on the live-birth rate of PGD-A over repeated cycles. AIM: To assess the cumulative live-birth rates (CLBR) of PGD-A compared with morphological assessment of embryos of up to three 'complete ART cycles' (fresh plus frozen/thaw cycles) in women aged 37 years or older. MATERIALS AND METHODS: A retrospective cohort study of ART treatments undertaken by ART-naïve women at a large Australian fertility clinic between 2011 and 2014. Cohorts were assigned based on the embryo selection method used in their first fresh cycle [PGD-A, n = 110 women (PGD-A group); morphological assessment of embryos, n = 1983 women (control group)]. CLBR, time to clinical pregnancy and cycles needed to achieve a live birth were measured over multiple cycles. RESULTS: Compared to the control group, the PGD-A group achieved a higher per cycle live-birth rate (14.47% vs 9.12%, P < 0.01), took a shorter mean time to reach a clinical pregnancy leading to a live-birth (104.8 days vs 140.6 days, P < 0.05) and required fewer cycles to achieve a live-birth (6.91 cycles vs 10.96 cycles, P < 0.01). However, after three 'complete ART cycles', the CLBR was comparable for the two groups (30.90% vs 26.77%, P = 0.34). CONCLUSION: This is the first study to assess the effectiveness of PGD-A over multiple ART cycles. These real-world findings suggest that PGD-A leads to better outcomes than using morphological assessment alone in women of advanced maternal age.

The clinical effectiveness of preimplantation genetic diagnosis for aneuploidy in all 24 chromosomes (PGD-A): systematic review.

STUDY QUESTION: Is preimplantation genetic diagnosis for aneuploidy (PGD-A) with analysis of all chromosomes during assisted reproductive technology (ART) clinically and cost effective? SUMMARY ANSWER: The majority of published studies comparing a strategy of PGD-A with morphologically assessed embryos have reported a higher implantation rate per embryo using PGD-A, but insufficient data has been presented to evaluate the clinical and cost-effectiveness of PGD-A in the clinical setting. WHAT IS KNOWN ALREADY: Aneuploidy is a leading cause of implantation failure, miscarriage and congenital abnormalities in humans, and a significant cause of ART failure. Preclinical evidence of PGD-A indicates that the selection and transfer of euploid embryos during ART should improve clinical outcomes. STUDY DESIGN, SIZE AND DURATION: A systematic review of the literature was performed for full text English language articles using MEDLINE, EMBASE, SCOPUS, Cochrane Library databases, NHS Economic Evaluation Database and EconLit. The Downs and Black scoring checklist was used to assess the quality of studies. Clinical effectiveness was measured in terms of pregnancy, live birth and miscarriage rates. PARTICIPANTS/MATERIALS, SETTINGS, METHODS: Nineteen articles meeting the inclusion criteria, comprising three RCTs in young and good prognosis patients and 16 observation studies were identified. Five of the observational studies included a control group of patients where embryos were selected based on morphological criteria (matched cohort studies). MAIN RESULTS AND ROLE OF CHANCE: Of the five studies that included a control group and reported implantation rates, four studies (including two RCTs) demonstrated improved implantation rates in the PGD-A group. Of the eight studies that included a control group, six studies (including two RCTs) reported significantly higher pregnancy rates in the PGD-A group, and in the remaining two studies, equivalent pregnancies rates were reported despite fewer embryos being transferred in the PGD-A group. The three RCTs demonstrated benefit in young and good prognosis patients in terms of clinical pregnancy rates and the use of single embryo transfer. However, studies relating to patients of advanced maternal age, recurrent miscarriage and implantation failure were restricted to matched cohort studies, limiting the ability to draw meaningful conclusions. LIMITATIONS, REASONS FOR CAUTION: Relevant studies may have been missed and findings from RCTs currently being undertaken could not be included. WIDER IMPLICATIONS OF THE FINDINGS: Given the uncertain role of PGD-A techniques, high-quality experimental studies using intention-to-treat analysis and cumulative live birth rates including the comparative outcomes from remaining cryopreserved embryos are needed to evaluate the overall role of PGD-A in the clinical setting. It is only in this way that the true contribution of PGD-A to ART can be understood.

Genome-wide karyomapping accurately identifies the inheritance of single-gene defects in human preimplantation embryos in vitro.

PURPOSE: Our aim was to compare the accuracy of family- or disease-specific targeted haplotyping and direct mutation-detection strategies with the accuracy of genome-wide mapping of the parental origin of each chromosome, or karyomapping, by single-nucleotide polymorphism genotyping of the parents, a close relative of known disease status, and the embryo cell(s) used for preimplantation genetic diagnosis of single-gene defects in a single cell or small numbers of cells biopsied from human embryos following in vitro fertilization. METHODS: Genomic DNA and whole-genome amplification products from embryo samples, which were previously diagnosed by targeted haplotyping, were genotyped for single-nucleotide polymorphisms genome-wide detection and retrospectively analyzed blind by karyomapping. RESULTS: Single-nucleotide polymorphism genotyping and karyomapping were successful in 213/218 (97.7%) samples from 44 preimplantation genetic diagnosis cycles for 25 single-gene defects with various modes of inheritance distributed widely across the genome. Karyomapping was concordant with targeted haplotyping in 208 (97.7%) samples, and the five nonconcordant samples were all in consanguineous regions with limited or inconsistent haplotyping results. CONCLUSION: Genome-wide karyomapping is highly accurate and facilitates analysis of the inheritance of almost any single-gene defect, or any combination of loci, at the single-cell level, greatly expanding the range of conditions for which preimplantation genetic diagnosis can be offered clinically without the need for customized test development.

What next for preimplantation genetic screening?

Preimplantation genetic diagnosis for aneuploidy screening (preimplantation genetic screening-PGS) has been used to detect chromosomally normal embryos from subfertile patients. The main indications are advanced maternal age (AMA), repeated implantation failure, repeated miscarriages and severe male factor infertility. Many non-randomized PGS studies have been published and report an increase in implantation rate, and/or a decrease in miscarriage rate. Recently, two randomized controlled trials have been conducted on patients with AMA as the only indication. Neither study showed a benefit in performing PGS using live birth rate as the measure of success. The debate on the usefulness of PGS is ongoing; the only effective way to resolve the debate is to perform more well-designed and well-executed randomized clinical trials.

Comparative genomic hybridization on single cells.

Comparative genomic hybridization (CGH) is a molecular cytogenetic technique developed for the analysis of chromosome imbalance in tumors and constitutional chromosome abnormalities. It is based on the analysis of genomic DNA and has the advantage over conventional karyotyping in that it does not require that metaphase chromosomes be obtained from the test material. The application of CGH to single cells requires whole-genome amplification of the DNA to provide sufficient DNA for use as a test sample. This approach has been used successfully to identify aneuploidy in single fibroblasts, amniocytes, and buccal cells that were known to be trisomic. CGH can also identify chromosome errors in single blastomeres from early embryos and in first polar bodies. We have analyzed biopsied blastomeres from embryos conceived by in vitro fertilization using CGH in a clinical preimplantation diagnostic program in which euploid embryos are selected for transfer. This has resulted in established pregnancies in patients with recurrent implantation failure.

Preimplantation aneuploidy screening using comparative genomic hybridization or fluorescence in situ hybridization of embryos from patients with recurrent implantation failure.

OBJECTIVE: To select chromosomally euploid embryos for transfer by analyzing single biopsied blastomeres using either fluorescence in situ hybridization (FISH) for chromosomes 13, 16, 18, 21, and 22 or comparative genomic hybridization (CGH), which provides a full karyotype. DESIGN: Prospective observational study. SETTING: A large IVF unit and the research laboratory of a hospital clinical genetics unit. PATIENT(S): Twenty patients with recurrent implantation failure. INTERVENTION(S): Ovarian stimulation and IVF by intracytoplasmic sperm injection (ICSI), embryo biopsy, and embryo transfer. MAIN OUTCOME MEASURE(S): Chromosome normality of biopsied blastomeres and implantation and clinical pregnancy rates. RESULT(S): Comparative genomic hybridization was able to identify many chromosomal abnormalities that would have been missed if those cells had been analyzed by FISH. The clinical pregnancy rate per transfer and implantation rate was 11% and 7% for embryos analyzed by FISH and 21% and 15% for embryos analyzed by CGH. CONCLUSION(S): Comparative genomic hybridization is more effective than FISH for identifying chromosomally normal embryos, which may result in a higher clinical pregnancy rate and implantation rate after embryo transfer.

High incidence of complex chromosome abnormality in cleavage embryos from patients with repeated implantation failure.

OBJECTIVE: To analyze the chromosome abnormalities observed in the course of preimplantation aneuploidy screening using comparative genomic hybridization (CGH) on single blastomeres in relation to maternal age and previous IVF history. DESIGN: Retrospective analytical study. SETTING: A large IVF unit and the research laboratory of an associated clinical genetics unit. PATIENT(S): Twenty-eight women referred for aneuploidy screening of cleavage embryos. INTERVENTION(S): Blastomere biopsy. MAIN OUTCOME MEASURE(S): The incidence of aneuploidy and complex abnormality in human cleavage embryos. RESULT(S): The incidence in embryos of aneuploidy for one to two chromosomes was significantly increased with advanced maternal age, but was independent of any history of recurrent implantation failure. In comparison, the incidence of complex chromosome abnormality (which involves three or more chromosomes) was independent of maternal age but significantly increased in embryos from patients with a history of recurrent implantation failure. CONCLUSION(S): The incidence of complex abnormality in healthy cleavage embryos is independent of maternal age but is increased in patients with a history of recurrent implantation failure. These results suggest that the pathology underlying complex abnormality is different from that resulting in aneuploidy of one to two chromosomes but particularly relevant to women with recurrent implantation failure.

Preimplantation genetic diagnosis and chromosome analysis of blastomeres using comparative genomic hybridization.

Numerical chromosome errors are known to be common in early human embryos and probably make a significant contribution to early pregnancy loss and implantation failure in IVF patients. Over recent years fluorescent in situ hybridization (FISH) has been used to document embryonic aneuploidies. Many IVF laboratories perform preimplantation genetic diagnosis (PGD) with FISH to select embryos that are free from some aneuploidies in an attempt to improve implantation, pregnancy and live birth rates in particular categories of IVF patients. The usefulness of FISH is limited because only a few chromosomes can be detected simultaneously in a single biopsied cell. Complete karyotyping at the single cell level can now be achieved by comparative genomic hybridization (CGH). CGH enables not only enumeration of all chromosomes but gives a more complete picture of the entire length of each chromosome and has demonstrated that chromosomal breakages and partial aneuploidies exist in embryos. CGH has provided invaluable information about the extent of mosaicism and aneuploidy of all chromosomes in early human conceptuses. CGH has been applied to clinical PGD and has resulted in the birth of healthy babies from embryos whose full karyotype was determined in the preimplantation phase.

Preimplantation genetic diagnosis for aneuploidy screening in early human embryos: a review.

Embryonic aneuploidies may be responsible for pregnancy failure in many IVF patients. In recent years, fluorescent in situ hybridisation (FISH) for multiple chromosomes has been used to document a high frequency of chromosomal errors and aneuploidy in human preimplantation embryos and, after embryo biopsy, to select embryos that are more likely to implant. Such studies suggest that women with recurrent miscarriage and advanced maternal age may benefit most from preimplantation genetic diagnosis with aneuploidy screening (PGD-AS). The success of PGD-AS is likely to be enhanced by new technologies, such as comparative genomic hybridisation, which enable full karyotyping of single cells.

A modified cryopreservation method increases the survival of human biopsied cleavage stage embryos.

BACKGROUND: The relatively poor survival rate of human biopsied cleavage stage embryos following cryopreservation is a significant obstacle in the application of preimplantation genetic diagnosis (PGD). We have attempted to improve cryosurvival of biopsied embryos by modifying the standard embryo cryopreservation technique. METHODS: Biopsied embryos were cryopreserved in 1.5 mol/l 1,2-propanediol in the presence of an elevated concentration of sucrose (0.2 mol/l) and human serum albumin was replaced by maternal serum (20% vol:vol). An additional initial thawing step in the presence of 0.3 mol/l sucrose was also included. RESULTS: The proportion of biopsied embryos which survived cryopreservation with > or =50% of their blastomeres intact was significantly higher using the modified method (138/185; 75%) than that observed using the standard propanediol method (20/46; 43%; P = 0.022). Total blastomere survival was also significantly increased as a result of the modifications (1010/1513; 67% versus 177/385; 46%; P < 0.001). Six fetal hearts have been detected to date following replacement of biopsied embryos cryopreserved with the modified method. CONCLUSIONS: Survival of human biopsied cleavage stage embryos can be restored to a level similar to that of non-biopsied controls by modification of the cryopreservation procedure. Embryos which have been cryopreserved using the modified method can implant following replacement in utero.