Presence of embryonic DNA in culture medium

Preimplantation genetic diagnosis (PGD) has successfully assisted couples with genetic diseases to conceive healthy babies during the past decades. However, biopsy of the blastomere has potential lesion to the embryos which commonly results in abortion. Thus, a noninvasive PGD is needed. In the past, the presence of genetic materials in maternal plasma or serum has triggered a great innovation of noninvasive prenatal diagnosis. Nevertheless, it is not clear whether embryonic DNA is also present in embryonic culture medium. Here, a rapid-boiling method has been used to harvest DNA from the medium or the discarded embryos, following Polymerase Chain Reaction (PCR) was applied to detect the dissociative DNA by amplifying SRY gene (Y-chromosome). For the first time, the Y sequences were detected in the medium which were used to culture embryo for above 3 days. None of the positive signal was examined in Day 1 and Day 2 embryonic culture medium. Our findings suggest that the Y chromosome fragments from the embryo may release into its culture medium. If validated in a larger cohort, detection of SRY gene may prove to be a useful method to screen Y-linked genetic disease. More importantly, detecting the free DNA in the embryonic culture medium may represent a novel strategy for noninvasive PGD.