In preparation of pregnancy and parenthood, chromosomal testing of embryos is an important step in the IVF or ICSI process. The doctor will select the embryo before it is transferred into the uterus and the embryo’s chromosomes will be tested in a process called next-generation sequencing (NGS). This process thoroughly examines the embryo on a chromosomal and genetic level to screen for genetic abnormalities.
In the ICSI process, the embryo will be developed into a blastocyst before cells can be extracted for NGS. This allows the family to select the highest quality embryo, without any chromosomal abnormalities, to be transferred into the uterus. This technique also increases the chances of a successful pregnancy after embryo transfer.
Next-Generation Sequencing (NGS)
Next-generation sequencing (NGS) is a technology that looks for extra or missing chromosomes in an embryo to increase the chances of implantation after transfer, decrease the risk of miscarriage in the first trimester, and decrease the risk of fetal chromosomal abnormalities, which can lead to congenital problems in the baby.
NGS can detect abnormalities in all 23 pairs of chromosomes in one procedure. It is highly accurate and has the lowest false positive rate of other similar techniques. NGS can also analyze hereditary diseases caused by abnormal genes.
NGS is widely used in hospitals and laboratories of fertility clinics to research and diagnose various diseases as well as problems with the embryo before implantation in the uterus.
What does Next-Generation Sequencing can check?
Normally humans have 46 chromosomes or 23 pairs. If there are any abnormalities, such as an extra or missing chromosome, this can lead to problems with the baby.
The most common chromosomal abnormality found is Down syndrome, which is caused by an extra 21st chromosome. This can lead to mental retardation as well as various physical disabilities, such as congenital heart disease and hypothyroidism.
An extra 13th or 18th chromosome can lead to severe disabilities and most of these babies don’t live very long after birth.
In the first trimester, chromosomal abnormalities in the fetus usually results in a higher chance of miscarriage. NGS is a method for genetic analysis that is part of intracytoplasmic sperm injection (ICSI).
NGS has been developed to screen for chromosomal abnormalities by pulling certain cells from 3-day (cleavage stage) or 5-day (blastocyst) embryo to be examined before the embryo is transferred to the uterus.
The main objective of NGS is to screen for Down syndrome and thalassemia as well as the completeness of the 23 pairs of chromosomes to increase the chances of a successful and healthy pregnancy.
Pros & Cons of Next-Generation Sequencing
Pros
- Detect abnormalities in the embryo before transfer.
- Decrease the risk of termination due to abnormalities with the embryo.
- Able to choose the highest quality embryo for transfer.
- Increase the chances of pregnancy.
- Decrease passing down genetic conditions from generation to generation.
Cons
- Risk of damage to the embryo if not performed by a specialist.
- NGS results take time so transfer will have to be delayed.
Who should consider Next-Generation Sequencing?
NGS is chromosomal screening of embryos done as part of the ICSI process and is recommended when:
- The female partner is over 35 and is experiencing infertility.
- The family has a history of recurrent miscarriages without any known causes
- There is a family history of hereditary abnormalities.
- There have been multiple attempts IUI/IVF/ICSI with no success.
Preparation for Next-Generation Sequencing
No preparation is necessary for NGS as it is just one step in the IVF/ICSI process. Chromosomal screening of the embryo is done before it is transferred to the uterus.
Conclusion
If a couple is considered at risk of producing embryos with chromosomal abnormalities, it is important they speak with a fertility specialist about using IVF/ICSI with NGS to screen for possible genetic conditions in the embryo. This increases the chances of pregnancy, decreases the risk of genetic conditions, and ensures that the healthiest embryos are transferred. If you have any questions or would like more information, please contact us on Line at @beyondivf