Chromosomal aneuploidy in embryos conceived with unstimulated cycle IVF (original) (raw)
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Journal of In Vitro Fertilization and Embryo Transfer, 1990
In vitro fertilization cycles yield a low percentage of pregnancies, Eighty-five to ninety percent of the transferred embryos do not implant, and the abortion rate approaches 30%. Aneuploidy is assumed to be responsible for a major portion of this pregnancy wastage. The purpose of this study was to determine if there was any correlation between morphology and chromosomal content of unfertilized oocytes and rejected embryos. To assess the chromosomal content of oocytes and embryos, we used the method described by Tarkowsld in 1966. Sixty oocytes from 28 women, aged between 27 and 41 years, were analyzed. Sixty-seven percent were aneuploid; of these, 23.35% were hyperhaploid, 23.35% were hypohaploid, 8.35% were hyperdiploid, 3.35% were diploid, and 8.35% showed premature chromosome condensation. Of 20 preimplantation embryos analyzed, 80% were aneuploid, 10% were diploid, 5% were haploid, and 5% showed structural anomaly. Correlation was found between maternal age and aneuploidy in oocytes and between morphology and genetic balance in preimplantation embryos.
Positive outcome after preimplantation diagnosis of aneuploidy in human embryos
Chromosomal abnormalities are responsible for a great deal of embryo wastage, which is reflected, at least partially, in decreased implantation and increased miscarriage in older women. To address this problem the transfer of only chromosomally normal embryos previously selected by preimplantation genetic diagnosis (PGD) has been proposed. We designed a multi-centre in-vitro fertilization (IVF) study to compare controls and a test group that underwent embryo biopsy and PGD for aneuploidy. Patients were matched retrospectively, but blindly, for average maternal age, number of previous IVF cycles, duration of stimulation, oestradiol concentrations on day ⍣1, and average mature follicles. All these parameters were similar in test and control groups. Only embryos classified as normal for those chromosomes were transferred after PGD. The results showed that the rates of fetal heart beat (FHB)/embryo transferred between the control and test groups were similar. However, spontaneous abortions, measured as FHB aborted/FHB detected, decreased after PGD (P < 0.05), and ongoing pregnancies and delivered babies increased (P < 0.05) in the PGD group of patients. Two conclusions were obtained: (i) PGD of aneuploidy reduced embryo loss after implantation; (ii) implantation rates were not significantly improved, but the proportion of ongoing and delivered babies was increased.
Medical Genetics and Genomics in the era of Personalized Medicine [Working Title]
Aneuploidy, the hold of an abnormal number of chromosomes that differs from the normal karyotype, is a recognized leading cause of miscarriage and congenital disabilities. In human gametes and embryos, aneuploidy rates are prevalent, and these rates increase with advanced maternal age; additionally, it has been suggested that hormonal stimulation for achieving in vitro fertilization (IVF) protocols further increases aneuploidy rates. Although about 65% of chromosomally abnormal embryos culminate in spontaneous miscarriages, there is still evidence of live births harboring crucial aneuploidies. Furthermore, although some frequent aneuploidies are consistent, others differ between countries, making it harder to focus on a specific set of anomalies but vital to focus regionally on those more prevalent. Preimplantation genetic testing (PGT) is a highly endorsed technique in assisted reproductive treatments to evaluate possible embryo aneuploidies, genetic defects, and congenital disorders. On this subject, this study shows that IVF aneuploidy rates in embryo cohorts of high morphological quality are inversely associated with implantation rates. In its entirety, this study reinforces the utility of PGT for embryo evaluation.
Human Reproduction, 2007
BACKGROUND: Preimplantation genetic screening (PGS) is used to determine the chromosome status of human embryos from patients with advanced maternal age (AMA), recurrent miscarriage (RM) or repeated implantation failure (RIF). METHODS: Embryos from 47 such couples were investigated for chromosomes 13, 15, 16, 18, 21 and 22 using fluorescence in situ hybridization with two rounds of hybridization. The investigation included parental lymphocyte work-up, the screening of blastomeres on day 3 and full follow-up on day 5/6 of untransferred embryos. RESULTS: The outcome of 60 PGS cycles is described, in which 523 embryos were biopsied; 91% gave results, of which 18% were diploid for all the chromosomes tested and 82% were abnormal. The pregnancy rate per cycle that reached the biopsy stage was 27%, and 30% per embryo transfer. Satisfactory follow-up was obtained from 353 embryos; all those diagnosed as abnormal were confirmed as such, although two false-positives were detected in relation to specific chromosome abnormalities. Meiotic errors were identified in 16% of embryos. Between the RM, AMA and RIF groups, there was a significant difference in the distribution of embryos that were uniformly abnormal and of those with meiotic errors; with an almost 3-fold increase in meiotic errors in the first two groups compared with the RIF group. CONCLUSIONS: This complete investigation has identified significant differences between referral groups concerning the origin of aneuploidy in their embryos.
International Journal of Reproductive BioMedicine, 2017
Background: Selection of the best embryo for transfer is very important in assisted reproductive technology (ART). Using morphological assessment for this selection demonstrated that the correlation between embryo morphology and implantation potential is relatively weak. On the other hand, aneuploidy is a key genetic factor that can influence human reproductive success in ART. Objective: The aim of this lab trial study was to evaluate the incidence of aneuploidies in five chromosomes in the morphologically high-quality embryos from young patients undergoing ART for sex selection. Materials and Methods: A total of 97 high quality embryos from 23 women at the age of 37or younger years that had previously undergone preimplantation genetic screening for sex selection were included in this study. After washing, the slides of blastomeres from embryos of patients were reanalyzed by fluorescence in-situ hybridization for chromosomes 13, 18 and 21. Results: There was a significant rate of aneuploidy determination in the embryos using preimplantation genetic screening for both sex and three evaluated autosomal chromosomes compared to preimplantation genetic screening for only sex chromosomes (62.9% vs. 24.7%, p=0.000). The most frequent detected chromosomal aneuploidy was trisomy or monosomy of chromosome 13. Conclusion: There is considerable numbers of chromosomal abnormalities in embryos generated in vitro which cause in vitro fertilization failure and it seems that morphological characterization of embryos is not a suitable method for choosing the embryos without these abnormalities.
Fertility and Sterility, 2005
To verify whether advantages can derive from the implementation of preimplantation genetic diagnosis for aneuploidy in patients with a poor prognosis of full-term pregnancy, compared with conventional treatment procedures. Design: A randomized, controlled study. Setting: Reproductive Medicine Unit of the Società Italiana Studi Medicina della Riproduzione, Bologna, Italy. Patient(s): In a total of 262 stimulated cycles, women presented with the following poor-prognosis indications: maternal age of Ն36 years (n ϭ 157), Ն3 previous IVF failures (n ϭ 54), and an altered karyotype (n ϭ 51). After giving consent, 127 patients underwent preimplantation genetic diagnosis for aneuploidy, whereas 135 controls underwent assisted zona hatching. Intervention(s): Analysis of chromosomes XY, was carried out with the fluorescence in situ hybridization technique in a blastomere biopsied from day 3 embryos. Assisted zona hatching was performed on day 3 embryos from the control group. Main Outcome Measure(s): Embryo morphology and chromosomal status, number of transferred embryos, clinical pregnancies, implantation rates, and abortions.