Genetic screening in IVF explained
A new study has been published in the Journal of Clinical Medicine, exploring the benefits of genetic testing for IVF-created embryos in women over 35.
Conducted by a research team from King’s College London, King’s College Hospital and King’s Fertility, this was the first study of its kind to look specifically at women aged 35 plus, and found that genetic screening of embryos could help women aged 35-42 successfully conceive in a shorter timeframe.
Although the sample size was too small to be considered statistically significant, the positive difference in cumulative live birth rate in those women who underwent genetic screening was large enough (72% compared to 52% in the control group) that the researchers believe the study merits a larger, multi-centre trial.
This could be exciting news for the IVF community, but genetic screening is not suitable for everyone, so here at Aria we’ve put together a list of FAQs to help you decide if it’s right for you.
What is genetic screening?
Genetic screening is a process that allows embryologists to check embryos that have been created through IVF for genetic and/or chromosomal abnormalities.
There are three different types of embryo screening:
PGT-A (aneuploidy testing)
This is the most common form of embryo screening and is looking for a genetic disorder called Aneuploidy. This is a condition that results in cells with either too many or too few chromosomes, potentially leading to life-limiting conditions such as Edward Syndrome or Patau Syndrome, and increasing the risk of miscarriage. During PGT-A screening, any embryos with more or less than the standard 46 chromosomes are not considered for transfer to the uterus.
PGT-M (monogenic testing)
Monogenic means single gene, so this test is looking for disorders associated with a single gene. PGT-M looks for specific genes carried by one or both parents, that might indicate genetic disorders like sickle cell anaemia or cystic fibrosis. Only embryos that are free of this specific gene would be transferred.
PGT-SR (structural rearrangements)
PGT-SR is looking for structural issues in the chromosomes, like segments that have been inverted, duplicated or are missing. Ensuring only embryos without these structural issues are implanted in the womb reduces the risk of failed implantation, miscarriage, birth defects or developmental issues.
How is genetic screening carried out?
The process is similar for all types of embryo screening:
- First, the embryos are created through IVF
- When the embryos reach five to six days old, a few cells are taken from the outer layer of each embryo
- The embryo is then frozen for the four to six weeks it takes for genetic testing to take place
- The cells that have been removed from the embryos are taken for genetic analysis
- Embryos that have been identified as healthy, without any genetic abnormalities, are then transferred to the uterus
- The usual IVF process continues
Who is suitable for genetic screening in IVF?
This process is not suitable for everyone. If you are younger than 35 and have no known risk factors, this could be an unnecessary additional step in the process. However, genetic screening can potentially help you achieve a viable pregnancy faster if:
- You are over 35 – the older you are, the higher the risk of chromosomal abnormalities
- You have a history of repeated miscarriage – some genetic disorders can increase the risk of miscarriage
- You or your partner has a family history of genetic disorders
- You are experiencing unexplained infertility or have undergone several failed IVF cycles
If you would like to know more about genetic screening in IVF and find out whether it might be helpful for you, one of our team will be happy to talk you through the process. Please contact us to make an appointment.