Advances in Genetic Testing: EmbryoScreen - | IVF Treatment | Monash IVF Australia

Advances in Genetic Testing: EmbryoScreen

There are some exciting advances occurring at Monash IVF in genetics with the introduction of technologies which will benefit our patients.

Preimplantation Genetic Screening (PGS) and Preimplantation Genetic Diagnosis (PGD) are treatment options available for patients at increased risk of passing a chromosome abnormality or specific genetic disease on to their children.

Monash IVF are pleased to announce the introduction of more sophisticated and robust testing methods that will enable greater peace of mind for our patients in this area. EmbryoScreen, is a new 23 chromosome screening test available in-house at Monash IVF. EmbryoScreen is based on cutting-edge Next Generation Sequencing (NGS) technology, which has been successfully integrated into our Genetics laboratory. We are pleased to be able to offer this advanced technology at $740 per embryo.

How does EmbryoScreen work?
Embryo biopsy is performed at the blastocyst stage on day 5/6 of development. The embryos are vitrified post-biopsy and pending PGS results.

The embryo biopsy sample is transferred to a small test tube. DNA from the biopsied cells is amplified using Whole Genome Amplification (to make millions of copies of the embryonic DNA). The amplified embryonic DNA is then fragmented. Hundreds of thousands of these small embryonic DNA fragments are sequenced in parallel. With the use of specialised computer software, each sequenced fragment is compared against the reference human genome and aligned with its corresponding chromosome region (much like putting the pieces of a jigsaw puzzle back together). The number of aligned sequences along the length of each of the chromosomes is then calculated. Because the number of aligned sequences should be proportional to the copy number present in the original sample, full trisomy or monosomy are able to be confidently identified based on a corresponding increase or decrease in the number of aligned sequences in proportion to the chromosome length. By counting the number of aligned sequences along the length of each chromosome, it is therefore possible to determine the copy number of all 23 chromosomes.

What are the benefits of EmbryoScreen and NGS?
EmbryoScreen is capable of performing 23 chromosome screening with significantly less background noise and potentially greater resolution than the currently available microarray technology. Furthermore, EmbryoScreen is capable of providing analysis of multiple embryos in a single sequencing run. This increased throughput will help to ensure that the current PGS turn around times are able to be maintained irrespective of the increasing demand for PGS. The flexibility of NGS and the ability to develop customised tests unlocks the potential for a wide range of future testing opportunities. Future developments could see the introduction of screening tests to determine the developmental potential of the embryo or to identify causes of infertility. These tests may, in turn, assist with the implementation of targeted treatment options.

Why perform EmbryoScreen?
There has been a significant uptake in PGS in the past year and this has once again demonstrated that embryo appearance isn’t everything. Embryos may look morphologically normal under the microscope but half of them don’t have the correct number of chromosomes even though they grow to blastocyst. These embryos either do not implant, result in miscarriages or give rise to chromosomally abnormal births (eg Downs Syndrome). By screening the embryos before we transfer them into the woman we can select for embryos with the correct number of chromosomes and therefore improve the likelihood of having a healthy baby. Because only embryos that have the potential to result in a baby are transferred, the number of treatment cycles to achieve a successful ongoing pregnancy is significantly reduced.

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