Array comparative genomic hybridization: its role in preimplantation genetic diagnosis.
ABSTRACT Embryo assessment is a crucial component to the success of IVF. A high rate of embryos produced in vitro present chromosomal abnormalities and have reduced potential for achieving a viable pregnancy. The use of preimplantation genetic diagnosis by array comparative genomic hybridization, for comprehensive aneuploidy screening of embryos, to improve IVF outcomes, is reviewed.
Data from comprehensive aneuploidy screening of embryos showed that aneuploidies may occur in any of the 24 chromosomes, indicating that aneuploidy screening of all chromosomes is necessary to determine whether an embryo is chromosomally normal. Initial studies on clinical application of this technology have documented improved pregnancy outcomes following transfer of screened embryos. The optimal stage of preimplantation development at which preimplantation genetic screening (PGS) should be performed still remains to be determined.
Although clinical results have been promising, further evidence is required to establish whether PGS results in enhanced live birth rate, and if this is the case, to identify which patients may benefit from the procedure. The results from several ongoing randomized controlled trials, performed at different cell biopsy stage and categories of patients, will provide the data needed to accept or reject the clinical efficacy of PGS.
- SourceAvailable from: Santiago Munné[show abstract] [hide abstract]
ABSTRACT: The relationship was examined between chromosome abnormalities in cleavage stage human embryos and maternal age, embryo morphology and development rate. Embryos that were classified as suboptimal for transfer from patients undergoing IVF treatment were disaggregated, and all or most of their cells were fixed for analysis by fluorescence in-situ hybridization. Chromosomes X, Y, 13, 18 and 21, and in some instances 16 were examined. A total of 731 non-viable embryos was analysed. An increase in chromosome abnormalities with decreasing embryo competence and increasing maternal age was shown. Compared with an earlier study, the major difference was that polyploidy (P<00.01) and aneuploidy were previously more common. After pooling results, it was found that aneuploidy increased with maternal age, from 3.1% in embryos from 20-34 years old patients to 17% in patients 40 years or older. Also, aneuploidy occurred more frequently in embryos with good morphology and development rate than in embryos developing poorly. In contrast, dysmorphic and slowly developing or arrested embryos had significantly more polyploidy and mosaicism than normally developing embryos. Clear associations between maternal age and aneuploidy, and between cleavage anomalies and mosaicism have been established in non-viable embryos. Arrested embryos were mostly polyploid. Moreover, polyploidy was found more frequently in embryos analysed on day 4, suggesting that developmentally compromised embryos became arrested in extended culture. A slightly higher aneuploidy rate in the earlier study may be attributed to differences in hormonal stimulation, which also resulted in different numbers of oocytes recruited and matured.Reproductive biomedicine online 01/2000; 1(1):17-26. · 2.68 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Single embryo transfer (SET) provides the most certain means to reduce the risk of multiple gestation. Regrettably, prospective trials of SET have demonstrated reductions in per-cycle delivery rates. A validated method of comprehensive chromosome screening (CCS) has the potential to optimize SET by transferring only euploid embryos. This retrospective study evaluates the efficacy of SET with CCS in an infertile population. Overall and age-controlled ongoing pregnancy rates (OPR) were compared between women undergoing SET following CCS (CCS-SET, n= 140) and those undergoing SET without aneuploidy screening (control SET, n= 182). All transfers were at the blastocyst stage, with CCS performed after trophectoderm biopsy of expanded blastocysts and analysis with rapid PCR allowing for fresh transfer. In the CCS-SET and control SET groups, an OPR of 55.0 and 41.8%, respectively, was obtained. The OPR was lower for the control group (P< 0.01) despite a younger age than the CCS group (37.3 ± 3.4 versus 34.2 ± 3.9 years; P< 0.001). Birthweight and gestational age at delivery were equivalent. The proportion of clinical pregnancies resulting in miscarriage was higher in the control group (24.8 versus 10.5%, P< 0.01), with more patients requiring surgical interventions for aneuploid pregnancies. There was one monozygotic twin delivery in the CCS group and none in the control group. Compared with traditional blastocyst SET, SET after trophectoderm biopsy and rapid PCR-based CCS increases OPR and reduces the miscarriage rate. The enhanced selection empowered by CCS with SET may provide a practical way to eliminate multi-zygotic multiple gestation without compromising clinical outcomes per cycle.Human Reproduction 02/2012; 27(4):1217-22. · 4.67 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: To evaluate the frequency of specific aneuploidies in miscarriages in an infertility practice and calculate the potential sensitivities of the different aneuploidy screening options for preimplantation genetic diagnosis (PGD) in this setting. Retrospective analysis. Academic reproductive endocrinology and infertility practice. Women with miscarriages that had karyotype analysis on products of conception. None. Karyotype of spontaneous abortions compared with commercially available PGD options. Of the 273 karyotypes analyzed, 177 (64.8%) were abnormal. The average age of the patients was 37 +/- 4.5 years. Using a limited five-probe panel, 54 of the 177 (31%) abnormal karyotypes would have been detected. In contrast, an extended PGD panel (using 9, 10, or 12 chromosome probes) would have detected 127, 131, and 140 of 177 abnormalities, 72%, 74%, and 79% respectively. The difference between the limited (5-probe) and extended (9-, 10-, and 12-probe) panels was statistically significant. There was not a statistically significant difference among the extended panels. Most of the abnormalities seen in miscarriages are detectable by PGD with extended panels. A significantly higher percentage of these abnormalities could be detected by screening for 9, 10, or 12 chromosomes compared with only 5.Fertility and sterility 03/2008; 89(2):353-7. · 3.97 Impact Factor