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Embryonic DNA Sampled after IVF for First Time Without Biopsy

Preimplantation genetic diagnosis (PGD) technologies allow identification of genetic disorders in human preimplantation embryos after in vitro fertilization (IVF) and before the embryo is transferred back to the patient. This technique allows couples with a high risk of passing on inherited diseases, to increase their chances of having a healthy baby. Despite the theoretical benefits of PGD, clinical outcomes using these technologies vary, possibly because of the need to remove one or more cells from the embryo using biopsy. In a study published on March 13, 2013 in Reproductive Biomedicine Online, a group of researchers from Italy and the United Kingdom sought to achieve diagnosis of genetic disease in embryonic DNA without the use of a biopsy. By extracting fluid from human embryos at the blastocyst stage they found that it contains DNA from the embryo. Blastocysts are 5- or 6-day-old embryos and are at the last free-living stage that can be studied in the laboratory prior to transfer into the uterus. Blastocysts contain between 50 and 300 cells that surround a fluid-filled cavity called the blastocoel.. The researchers carefully removed fluid from the blastocoel, leaving the cells intact. The sampled blastocysts were subsequently cryopreserved. This study employed real-time PCR to show that genomic DNA was present in about 90% of blastocoele fluid samples harvested. Moreover, the potential for determining embryo sex directly from blastocoele fluid was demonstrated by amplifying the multicopy genes TSPY1 (on the Y chromosome) and TBC1D3 (on chromosome 17). The authors said this opens up the possibility of screening embryos from couples carrying an X-linked disorder to identify male embryos at high risk of disease. In addition, the application of whole-genome amplification technologies to fluid samples was also shown to be feasible, potentially allowing more comprehensive genetic tests. As proof of principle, the authors said that microarray comparative genomic hybridization was attempted to confirm the sex of embryos, as well as to detect several aneuploidies. They noted, however, that further studies would be needed to validate this approach and confirm that the accuracy is sufficient for diagnostic purposes. "This is the first time that embryonic DNA has been detected in the human blastocyst without the use of biopsy," explained lead researchers Simone Palini. Ph.D., from the IVF Unit at Cervesi Hospital in Cattolica, Italy, Dr. Luca Galluzzi from the University of Urbino in Italy and Dr. Dagan Wells from the University of Oxford, United Kingdom. "This is a technique that most embryologists can easily master," said Dr. Carlo Bulletti who directs the IVF team at Cervesi Hospital Cattolica. Professor Mauro Magnani, Chairman of the Department of Biomolecular Sciences of the University of Urbino, added. "More work needs to be done to confirm our results, but we hope that this approach will ultimately help infertile couples achieve their dream of having a family. It may also improve the options for families affected by severe inherited conditions, helping them to have healthy babies." "Even though it is only a preliminary finding, this approach may allow for genetic testing of the embryo without the complexity of cell sampling," said Joe Leigh Simpson, M.D., Senior Vice President for Research Programs, March of Dimes Foundation and President, International Federation of Fertility Societies (IFFS), a pioneer in reproductive medicine and genetics. [Press release] [Reproductive Biomedicine Online]