DNA Fingerprinting Identifies Viable IVF Embryos

By Jennifer Lahl

Has the era of high tech embryo profiling arrived? I have been following the recent study published in the journal Human Reproduction. Researchers have combined the technology that allows them to screen embryos at the blastocyst stage with the DNA fingerprinting and microarray analysis technology in order to identify the viable blastocysts transferred into the mother. The search for the best embryo has always been part of the IVF equation with all the quality controls put in place in the lab.

So how is the research being conducted?

“The researchers tested the DNA of early in vitro fertilization embryos before implanting them into the womb, and then compared the results with the DNA of the healthy babies that were born, and found a cluster of genes that could be used to establish which embryos are likely to make it to full term.”

And why is this research touted as progress?

“The idea is that by using objective, measurable criteria rather than the current more subjective observations such as looking at the morphology of the blastocysts, the ability to predict which embryos are viable will improve to such an extent that IVF clinicians will be able to confidently implant single embryos without reducing pregnancy rates.”

Current methods of embryo testing and embryo grading occur daily in IVF clinics and are just part of the routine. I’ve always criticized embryo grading for being subjective, harmful and dangerous to the early embryo as well as just not a good indicator of the future health of the baby. We’re in dangerous waters here.

The timeline keeps getting moved back further and further in human development in our insatiable quest for the perfect people. We’ve become a people with zero tolerance with anything less than perfect.

Pre-implantation Genetic Diagnosis Reduces Live Birth Rate

Oops. Here we have been told that PGD, that is, removing one cell from an early embryo and testing to determine whether it is deemed worthy of implantation, does not harm embryos. Not so, perhaps. According to a study published in the New England Journal of Medicine:

Preimplantation genetic screening did not increase but instead significantly reduced the rates of ongoing pregnancies and live births after IVF in women of advanced maternal age. These results argue strongly against routinely performing preimplantation genetic screening as an adjunct to IVF in this group of women.

The study speculates on several potential causes:

Several mechanisms may be responsible for the failure of preimplantation genetic screening to improve the outcomes of IVF in women of advanced maternal age. It is possible that biopsy of a blastomere [cell] on day 3 of embryonic development hampers the potential of an embryo to successfully implant; however, the effect of biopsy alone on pregnancy rates has not been studied. Furthermore, the limitation in the number of chromosomes that can be analyzed with FISH could lead to the transfer of embryos labeled as normal that are in fact aneuploid for one or more chromosomes not tested. This problem may be overcome in the future by the use of new techniques, such as array comparative genomic hybridization, in which the complete ploidy status can be given for a blastomere after biopsy. Finally, many human embryos resulting from IVF may be mosaic, so that the chromosomal constitution revealed by analysis of the blastomere may not be representative of the entire embryo.

Interesting stuff. It appears that our attempts at hyper-control of progeny has a ways to go.

No word yet on whether this outcome impacts Advanced Cell Technology's assertion that it can obtain ES cells without harming embryos which uses the same PGD technique.