Chromosomal Test Research Articles

Selecting single euploid blastocysts for transfer with NGS significantly improves IVF treatment outcomes: a randomized study

Introduction Recent advancements in whole genomic amplification (WGA) and next-generation sequencing (NGS) have provided new methods for preimplantation genetic testing for aneuploidy (PGT-A) of human embryos derived from in vitro fertilization (IVF) cycles. The present study aimed to investigate the effects of NGS on clinical and ongoing pregnancy outcomes of single embryo transfer (SET) for IVF patients with a good prognosis. Material and Methods A total of 247 IVF patients at mean age 31.4 ± 3.2 years who met the inclusion criteria (under 35 years old with normal uterine lining and normal karyotype) were randomized into two groups: 1) Group A (MA+NGS): patients (n=124) had blastocysts evaluated with morphological assessment (MA) and analyzed with NGS (Yikon Genomics, China; Illumina, USA) and 2) Group B (MA): patients (n=123) had blastocysts evaluated with morphological assessment (MA) only. One blastocyst was selected and transferred to individual patients based on NGS and morphological assessment (Group A) or morphological assessment alone (Group B). Clinical and ongoing pregnancy (≥20 weeks of gestation) rates were compared between the two groups. Results There were no significant differences in female patient's mean age, Day 3 FSH, AMH, E2, antral follicle number between the two groups (p>0.05). NGS identified single euploid blastocysts for transfer and resulted in significantly higher clinical pregnancy rates per transfer in Group A compared to morphological assessment alone in Group B (71.7% vs. 52.1%, respectively, p =0.001). The ongoing pregnancy rates per transfer also significantly increased in Group A compared to Group B (69.2% vs. 46.3%, respectively, p =0.002). There were no twin or multiple pregnancies in both groups. Conclusions While NGS has been recently introduced to IVF treatment, this is the first randomized clinical study showing that there is clinical benefit of NGS for selecting single blastocysts for transfer for good prognosis patients in comparison to morphology assessment alone. With the observed high accuracy of 24-chromosome testing and the improved clinical and ongoing pregnancy outcomes, NGS has demonstrated an efficient, robust high-throughput technology for selecting single blastocysts for transfer for IVF patients with a good prognosis to reduce multiple pregnancies.

Preferential selection and transfer of euploid noncarrier embryos in preimplantation genetic diagnosis cycles for reciprocal translocations

To develop and validate a new strategy to distinguish between balanced/euploid carrier and noncarrier embryos in preimplantation genetic diagnosis (PGD) cycles for reciprocal translocations and to successfully achieve a live birth after selective transfer of a noncarrier embryo. Retrospective and prospective study. Invitro fertilization (IVF) units. Eleven patients undergoing mate pair sequencing for identification of translocation breakpoints, followed by clinical PGD cycles. Embryo biopsy with 24-chromosome testing to determine carrier status of balanced/euploid embryos. Definition of translocation breakpoints and polymerase chain reaction (PCR) diagnostic primers, correct diagnosis of euploid embryos for carrier status, and a live birth with a normal karyotype after transfer of a noncarrier embryo. In 9 of 11 patients (82%), translocation breakpoints were successfully identified. In four patients with a term PGD pregnancy established with a balanced/euploid embryo of unknown carrier status, the correct carrier status was retrospectively determined, matching with the cytogenetic karyotype of the resulting newborns. In a prospective PGD cycle undertaken by a patient with a 46,XY,t(7;14)(q22;q24.3) translocation, the four balanced/euploid embryos identified comprised three carriers and one noncarrier. Transfer of the noncarrier embryo resulted in birth of a healthy girl who was subsequently confirmed with a normal 46,XX karyotype. The combination of mate pair sequencing and PCR breakpoint analysis of balanced reciprocal translocation derivatives is a novel, reliable, and accurate strategy for distinguishing between carrier and noncarrier balanced/euploid embryos. The method has potential application in clinical PGD cycles for patients with reciprocal translocations or other structural rearrangements.

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

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. 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). 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 18weeks gestation, the karyotypes matched with the original PGD results. 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.

First systematic experience of 24-chromosome aneuploidy testing in PGD for HLA and single gene disorders

24 chromosome aneuploidy testing have been introduced for pre-selection of embryos with improved potential to result in clinical pregnancy. This has a unique potential to combine with PGD for monogenic disorders, as the testing can be done in the same biopsy material, avoiding the risk for trisomy in the pre-selected genetic disease free embryos. So the first experience of systematic PGD with concomitant testing for single gene disorders, HLA typing and 24 chromosome testing is presented, involving the application of this novel approach to 55 different genetic conditions.

Clinical Management of in Vitro Fertilization with Preimplantation Genetic Diagnosis

Patients who undergo in vitro fertilization (IVF) because of preimplantation genetic diagnosis (PGD) require different clinical management than those who come in because of infertility alone. PGD adds a "fourth dimension" to the emotional aspect of a patients' assisted reproductive technology treatment. It significantly decreases the number of embryos available for transfer by 25 to 81%, and therefore ovarian stimulation for IVF with PGD should be tailored individually, taking into account patients' safety and estimated ovarian reserve. Recent studies showed that with increased number of oocytes retrieved, the higher the chance to have an embryo transfer and normal cryopreserved blastocysts. With adequate ovarian stimulation, there is no cutoff for the numbers of oocytes/embryos needed to start PGD with, especially for younger patients. Patient-friendly protocols, such as those based on gonadotropin-releasing hormone antagonist and vaginal progesterone support may be used. Elective single embryo transfer and blastocysts cryopreservation to avoid multiple pregnancies may be offered with PGD. The benefit of adding preimplantation genetic screening to IVF treatment is still controversial, and evidence-based data on 24-chromosome testing of polar bodies or trophectoderm is needed before it may be implemented into routine patient care.This review discusses the clinical management of IVF with PGD based on the best available data and my personal clinical experience as a reproductive specialist with >1000 IVF/intracytoplasmic sperm injection-PGD cycles. The information provided here will assist reproductive specialists, nurses, geneticists, genetic counselors, and embryologists to better counsel and treat couples who wish to conceive with a healthy child through IVF with PGD. It is time for PGD to be viewed as a modern modality of preventive medicine. As such, it should be incorporated into national health-care systems and be covered by medical insurance.