One of the benefits of opting for In Vitro Fertilisation (IVF) is that patients may be tested for potential genetic problems before attempting an IVF cycle. Around 70% of embryos created either through natural conception or IVF/ICSI do not survive the first 3 months of pregnancy due to several genetic or chromosomal anomalies.
Preimplantation Genetic Testing for Aneuploidy= abnormal number of chromosomes (PGT-A or PGS) and Preimplantation Genetic Testing for Monogenic/single gene disorders (PGT-M or PGD) are extra stages of the procedure that patients are able to opt for if they are worried that there may be factors that might prevent them from conceiving without complications.
This is especially useful for determining whether a couple is liable to pass a genetically inherited abnormality on to their child. It may also be recommended for older patients, for those who have suffered multiple unexplained pregnancy losses or for those who have been through multiple failed rounds of IVF.
PGT is an additional service which can offer peace of mind to those wanting to rule out problems.
You may need to undergo Pre-implantation Genetic Testing if:
- Both partners are carriers of single gene mutations
- Partner has a chromosome rearrangement that can produce genetically abnormal eggs or sperm
- Pregnancy has been affected by a chromosomal abnormality
- Advanced maternal age
- Recurrent miscarriage
- Recurrent implantation [IVF] failure
There is a slight difference between PGT-A and PGT-M:
PGS or PGT-A screens for any chromosomal abnormalities that may be present, while PGD or PGT-M looks out for something specific.
If one or both of the parents are at risk of a particular chromosomal abnormality, PGD or PGT-M may be the right choice. Couples, or even single patients, who have a high risk of chromosomal abnormalities will be identified during their initial consultations, where their medical history will be discussed at length.
PGT-A or PGS on the other hand is a more suitable option for patients who have suffered unexplained miscarriages, or who are over 40 and want to start their cycle of IVF with all the facts at hand. Opting to carry out PGS will mean that the patients are aware of any issues that may prevent them from conceiving without genetic complications, and may even be offered the opportunity to avert them. Only healthy embryos are selected for transfer into the uterus.
The procedure involves undergoing a conventional IVF procedure. When embryos are in the developing stage, a few cells are removed from each embryo and tested in one of the two ways:
- Advanced embryo selection (Array CGH)
The procedure involves screening all 24 chromosomes in an embryo to facilitate the process of selection and transfer of chromosomally normal embryos.
If both of you are a carrier of a single gene disorder, then Karyomapping is performed. The procedure helps identifies the embryos that are not affected by the disorder, thus prevents the condition to transfer to the next generation.
Time to result
Benefits of PGT
- The procedure can be used to test over 100 genetic conditions
- PGD is carried out before implantation thus allowing the couple to decide on whether they want pregnancy
- Couples can have biological children
Risks of PGT
The following are a few risks associated with PGT:
- Although PGT helps reduce the chances of giving a birth to the child with the genetic disorder, it cannot eliminate the risk. In a few cases, further testing is required during pregnancy to eliminate the genetic disorder completely
- Pre-implantation genetic diagnosis does not substitute the prenatal testing.
Hope you got required information about the Preimplantation genetic diagnosis. If you want to know more, consult our specialists right away.
Opting for IVF with preimplantation genetic screening or preimplantation genetic diagnosis, will give you the best possible chance of falling pregnant on a sound genetic basis.