Identifying genetic abnormalities in embryos during in vitro fertilisation

Anil Biricik, Chief Scientific Officer IVF, Eurofins Genoma,
biricik@laboratoriogenoma.it

Various social and demographic changes have contributed significantly to the increase in the average maternal age and infertility rates. For this reason, both Assisted Reproductive Techniques (ART) and Preimplantation Genetic Testing (PGT) have seen strong growth over the past two decades.

PGT analyses the cells collected by biopsy of the embryo’s trophectoderm to identify numerical (PGT-A) and structural (PGT-SR) chromosomal abnormalities and genetic variants (PGT-M). However, potential biopsy-related safety issues, operator-dependent variability, regulatory obstacles and the risk of embryo mosaicism, which can lead to false positive and negative results, are inherent features of PGT.

For this reason, a promising new approach for the detection of embryonic aneuploidies, called noninvasive PGT-A (niPGT-A), is emerging. niPGT-A
analyses cell-free DNA (cfDNA) in the spent culture medium (SCM), in which the embryo is cultured without the need for a biopsy. This reduces costs and partly overcomes the problem of mosaicism, as cfDNA in the SCM is released from both the trophectoderm and the inner cell mass. Is it reliable and routinely applicable?

To answer this question, Eurofins Genoma, which has been active in the PGT field for more than 20 years, conducted a clinical validation study on more than 500 SCM samples to understand which in vitro culture time is most effective for efficient cfDNA analysis, achieving a high ploidy concordance rate between SCM and biopsied trophectoderm samples.

Therefore, niPGT-A in association with morphological criteria is a useful tool to prioritise embryos for implantation without the need to manipulate them and without operator-dependent limitations. Indeed, in the presence of regulatory or technological restrictions that prevent embryonic biopsy, niPGT-A offers the possibility to all first and second level in vitro fertilisation
laboratories, which can benefit from a better evaluation than morphological analysis alone, to select the embryos with highest implantation potential with the less harmful method.

For more information, visit: www.laboratoriogenoma.eu