Genomic DNA in human blastocoele fluid

IVF often requires embryo cryopreservation through vitrification. During the vitrification process, the embryos can be collapsed by withdrawing the blastocoele fluid. The metabolomic profile of blastocoele fluid has been recently investigated by high-performance liquid chromatography-electrospray ionization-mass spectrometry to provide metabolite information that can help estimations of implantation efficiency. However, the presence of embryo DNA in blastocoele fluid has not been reported to date. This study shows using real-time PCR that genomic DNA was present in about 90% of blastocoele fluid samples harvested during the vitrification procedure. Moreover, the potential for determining embryo sex directly from blastocoele fluid is demonstrated by amplifying the multicopy genes TSPY1 (on the Y chromosome) and TBC1D3 (on chromosome 17). This opens up the possibility of screening embryos from couples carrying an X-linked disorder to identify male embryos at high risk of disease. The application of whole-genome amplification technologies to fluid samples is also shown to be feasible, potentially allowing more comprehensive genetic tests. As proof of principle, microarray comparative genomic hybridization was attempted to confirm the sex of embryos as well as detect several aneuploidies. However, further studies are needed to validate this approach and confirm that the accuracy is sufficient for diagnostic purposes.