Since it was established in 1997, the ESHRE PGD Consortium has been collecting data from international preimplantation genetic diagnosis (PGD) centres. Ten papers have been published, including data from January 1997 to December 2007.
The data collection originally used a hard-copy format, then an excel database and finally a FileMaker Pro database. The indications are divided into five categories: PGD for chromosome abnormalities, sexing for X-linked disease, PGD for single gene defects, preimplantation genetic screening (PGS) and PGD for social sexing. The main end-points are pregnancy outcome and follow-up of deliveries.
In data collection I, 16 centres contributed data, which increased to 57 centres by data X (average of 39 centres per data collection). These centres contributed data on over 27 000 cycles that reached oocyte retrieval. Of these cycles, 61% were for aneuploidy screening, 17% for single gene disorders, 16% for chromosomal abnormalities, 4% for sexing of X-linked disease and 2% for social sexing. Cumulatively, 5187 clinical pregnancies gave rise to 4140 deliveries and 5135 newborns (singletons: 3182, twins: 921, triplets: 37).
In this paper, we present an overview of the first 10 years of PGD data, highlighting trends. These include the introduction of laser-assisted biopsy, an increase in polar body and trophectoderm biopsy, new strategies, methodologies and technologies for diagnosis, including recently arrays, and the more frequent use of freezing biopsied embryos. The Consortium data reports represent a valuable resource for information about the practice of PGD.
" or normal embryo following PGD for translocations . The ESHRE consortium reported in their XII data collection that 25% embryos were transferable for patients undergoing PGD for both reciprocal and Robertsonian translocations ( Moutou et al . , 2014 ) that is in agreement with the 10 years of ESHRE collected results ( 26% transferable embryos ) ( Harper et al . , 2012 ) . These collective data illustrate that there is a low chance of finding a balanced or normal embryo for transfer from patients undergoing PGD for translocations ."
[Show abstract][Hide abstract] ABSTRACT: Summary This study aimed to investigate the optimum number of embryos to be biopsied in order to increase the likelihood of obtaining a balanced/normal embryo following preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridisation (FISH) for translocation carriers. Patients with low number of fertilised oocytes (≤5) or low number of embryos available for PGD (<7) underwent multiple hormonal stimulation cycles and their embryos from each cycle were vitrified and accumulated to obtain at least three embryos for PGD. Fifty-seven PGD cycles were performed for translocation carriers by FISH on day 3 of embryo development. PGD and pregnancy outcomes were examined according to the number of embryos biopsied. The cancellation rates of embryo transfer for the reciprocal translocation carriers were 40% when more than eight embryos were biopsied and it was as high as 78% when low number of embryos (less than nine) were biopsied. For Robertsonian translocation carriers, when more than eight embryos were biopsied, there were no embryo transfer cancellations. This study showed that when there are more than nine embryos biopsied for PGD, the likelihood of obtaining a balanced embryo and positive pregnancy outcome is significantly higher (P < 0.05) in such the overall pregnancy rate was 63% for reciprocal and 86% for Robertsonian carriers. This was reduced to only 7% for reciprocal and 14% for Robertsonian translocation carriers when less than nine embryos were biopsied. One of the limitations of this study was that the analysis was performed by FISH and more studies should investigate the outcomes of embryo accumulation following comprehensive chromosome analysis.
"Genetic counselling was performed in a standardized way following the department protocol and included, amongst others, explanation of all procedures , complications, and risk of misdiagnosis. Couples were informed that live birth rate per started cycle is 15 – 20% and that not all oocyte retrievals lead to a transfer due to chromosomal imbalance in all embryos examined (Harper et al., 2012). In the study period, there were six different genetic counsellors. "
"Overall, during the 10 years of data collection by the European Society of Human Reproduction and Embryology (ESHRE), there have been 27,630 cycles to oocyte retrieval (OR) reported, that resulted in 202,357 fertilized oocytes and the transfer of 35,944 embryo. For 16% of these cycles the indication was chromosomal abnormalities
[Show abstract][Hide abstract] ABSTRACT: Background
Carriers of balanced translocations are at high risk for unbalanced gametes which can result in recurrent miscarriages or birth defects. Preimplantation genetic diagnosis (PGD) is often offered to select balanced embryos. This selection is currently mainly performed by array CGH on blastomeres. Current methodology does not take into account the phase of the cell cycle, despite the variable copy number status of different genomic regions in S phase.
Cell lines derived from 3 patients with different chromosomal imbalances were used to evaluate the accuracy of single cell array CGH. The different cell cycle phases were sorted by flow cytometry and 10 single cells were picked per cell line per cell cycle phase, whole genome amplified and analyzed by BAC arrays, the most commonly used platform for PGD purposes. In contrast to G phase, where the imbalances were efficiently identified, less than half of the probes in the regions of interest indicated the presence of the aberration in 17 S-phase cells, resulting in reduced accuracy.
The results demonstrate that the accuracy to detect segmental chromosomal imbalances is reduced in S-phase cells, which could be a source of misdiagnosis in PGD. Hence, the cell cycle phase of the analyzed cell is of great importance and should be taken into account during the analysis. This knowledge may guide future technological improvements.
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