PGS: A genetic test designed to increase the chance of IVF success
Written by Francisco Rodriguez Herrera, Business Development Director, Middle East & India, Igenomix
January 10, 2018
When it comes to infertility issues, in vitro fertilization (IVF) is one of the mostknown available treatments today especially for women over age 40.
IVF, a form of assisted reproductive technology (ART), is a process of fertilization where an egg and a sperm are combined in a laboratory dish. Once an embryois formed, it is transferred to the uterus. IVF is also used to address certain health conditions such as fallopian tube damage or blockage, endometriosis, anduterine fibroids.
Like in any other procedures, IVF treatment can have its own complications, too. Some couples suffer from repeated IVF failures, while others face the possibility of having a child with genetic disorder.
Scientists have discovered a way to reduce the chances of these complications from occurring. Preimplantation Genetic Diagnosis (PGD)for single gene disorders andPreimplantation Genetic Screening (PGS)for chromosomal abnormalitiesare normally performed in combination with IVF. The medical tests are especially recommended forcouples with a family history of genetic disorders, a previous child with genetic disorder, a history of repeated IVF failures, miscarriage, or termination of an abnormal pregnancy. PGD and PGS testing for genetic disorders and chromosomal abnormalities in embryos are extremely powerful ways of assessing risk for some patients.
PGD aims to identify genetic defects in embryos and determine if a particular embryo should be transferred during an IVF cycle or not. Recommended for patients who are carriers of single gene disorders and are at a high risk of having an affected child, the PGD process involves
selection of non-affected embryos before implantation and is generally performed on a small embryo biopsy prior to transfer during IVF cycle.
Studies have shown that the implantation rate prior to PGD was only 7.2 per cent in contrast to 34.8 per cent after PGD, or an almost five-fold improvement. Additionally, more than two-fold increase in take-home baby rate after PGD was recorded, which was as high as 65.7 per cent in PGD cycles compared with 27.9 per cent without PGD.
Igenomix experts, however, have noted the 50 per cent chance of having chromosomal aneuploidy in the normal embryosselected after PGD screening. This could still leadto IVF failure, miscarriage, or birth of a child with chromosomal abnormalities. As such, employing PGS with MitoScore after PGD could help rule out the possibility of chromosomal abnormalities and ensure a higher chance of implantation and pregnancy success in the single IVF cycle.
MitoScore is a mitochondrial biomarker developed by Igenomix that gives an indicator of the energy status of an embryo. PGS with MitoScorehelps select embryos which are chromosomally normal and have a greater chance of not only a successful pregnancy but also a healthy baby.
Choosing the right embryo is highly critical before implantation.For couples planning to undergo IVF treatment, it is recommended that they consult a genetic counselor first to fully know and understand the process, risks, and implications involved. It is best during this time to clarify expectations as well.The genetic counselor will also be able to explain accurately the benefits and risks involving PGD and PGS.
The bottom line is careful assessment of the entire procedures - even the success rate of the center where you plan to undergo the treatment - before pushing through with PGD and PGS in conjunction with IVF. Undergoing IVF treatment is always an emotional period for couples who have repeatedly tried but failed to get pregnant. Therefore, it pays to be empowered and knowledgeable of the whole processes.