The first 30 hours of embryo development are key to knowing whether the human embryo is going to be chromosomally normal and ensuring a successful pregnancy

Every year, 1.5% of the babies born in Europe are a result of assisted reproduction techniques, a trend that has been growing over the past 20 years as parenthood is postponed. According to European statistics, over half a million in vitro fertilisation (IVF) procedures are performed every year, resulting in 100,000 newborns.

Scientists from Igenomix, University of Valencia, Stanford University and the University of Oregon have discovered that it is possible to predict if a human embryo is going to be chromosomally normal or abnormal within the first 30 hours after the union of the nuclei of an egg and a sperm, and ensure the success of the pregnancy. It has been proven that, during this time, a group of genes controls the movement of the chromosomes causing the embryos to be normal or abnormal.

This discovery, published in the journal Nature Communications, could improve the success rates of IVF treatments, which are around 30%–35% worldwide. These low rates are mainly due to the fact that between 50% and 80% of the embryos generated during IVF contain genetic abnormalities, which prevent a pregnancy from reaching term successfully.

The main conclusions of this research show that it is possible to predict the chromosomal composition of the embryos based on their transcriptomic profile.

“The expression levels of only 12 genes are capable of predicting whether the embryo is chromosomally normal or abnormal with over 85% of reliability”, concludes María Vera, researcher at Igenomix and former visiting researcher at Stanford University.

Furthermore, another of the main results of the study was the detection of differences in the duration of the first mitotic phase of the embryo, which is crucial for a proper distribution of DNA. “We have found that this cellular cycle is, on average, 24 minutes longer in those embryos that have chromosomal abnormalities”, pointed out Prof. Carlos Simón, Scientific Director of Igenomix and one of the researchers of this study.

The results obtained during this study will provide a basis for non-invasive diagnostic tools that allow to predict chromosomal variation after IVF, as current pre-implantation genetic diagnosis requires an invasive analysis of the embryo using one of its cells.

Thanks to these discoveries, doctors and embryologists will be able to more quickly identify which embryos are healthy and are better candidates for being implanted in the maternal uterus. Furthermore, this early analysis of the embryos would significantly reduce the time of the embryo under culture, as in the current clinical routine embryos are not transferred until day 3 or 5 after fertilisation.

This research was conducted using 117 zygotes from couples with an average maternal age of 33.7 years. All the embryos were donated to Stanford University for the purpose of being used in future research to improve fertility problems. Thanks to these donations, researchers on this study were able to analyse the chromosome set, gene expression and time-lapse video for the first time to simultaneously obtain a full view of the viability and normality of the human embryo.

The study’s first author is María Vera-Rodríguez, M.S., researcher at Igenomix and former visiting researcher at Stanford University, and senior author is Carlos Simón, M.D., Ph.D., Professor of Obstetrics and Gynaecology at the University of Valencia, Adjunct Clinical Professor of Obstetrics and Gynaecology at the Stanford University School of Medicine, and Scientific Director at IGENOMIX and Instituto Valenciano de Infertilidad (IVI). Co-authors include Shawn L. Chavez, Ph.D. Assistant Scientist in the Division of Reproductive and Developmental Sciences at the National Primate Research Centre at Oregon Health and Sciences University (OSHU), and Assistant Professor of Obstetrics and Gynaecology, Physiology and Pharmacology in the OSHU School of Medicine; Carmen Rubio, Ph.D., Laboratory Director for PGD Molecular Cytogenetics at IGENOMIX; and Renee Reijo Pera, Ph.D., Vice President of Research and Economic Development at Montana State University.

Access the scientific paper here:

http://www.nature.com/ncomms/2015/150707/ncomms8601/full/ncomms8601.html

About Igenomix

IGENOMIX is a biotechnological company that offers advanced reproductive genetic services. Its great experience and its advanced research capacity make the company one of the world points of reference in this field and allow it to offer effective solutions adapted to different infertility problems. It has a presence in Valencia, Miami, Los Angeles, Sao Paulo, Dubai, and Delhi, and it has a staff of more than 150 qualified professionals all over the world.