IVF or in vitro fertilization is not only a very effective method of infertility treatment, but also an auxiliary method for diagnosing many congenital diseases before pregnancy. Preimplantation genetic diagnosis of embryos PGD (also called preimplantation genetic testing (PGT)) is an additional procedure to assisted reproductive technologies.
It is the testing of an in vitro fertilization (IVF) embryo for genetic abnormalities before the embryo is transferred to the uterus. In this way, it is possible to select healthy embryos even before their transfer stage.
Pre-implantation genetic diagnosis (PGT) opens up opportunities to become parents of a healthy child, giving the baby the chance to avoid congenital diseases.
Find out more: NGS – preimplantation genetic screening and PGD – preimplantation genetic diagnosis.
Thanks to the care and knowledge of our specialists, the first healthy children in Latvia for parents with hemophilia were born in year 2012.
If you have questions about PGT or want to know more about how PGT can help you, don’t hesitate to discuss it with our clinic doctors or a genetic counselor. Together, we can take a step towards a healthy and happy future for your family.
- Preimplantation genetic testing (PGT) examines embryos during IVF before they are potentially transferred to a woman’s uterus to detect a range of genetic problems that can lead to implantation failure, miscarriage and birth defects in the baby;
- These genetic defects include a missing or extra chromosome in the embryo (such as Down syndrome), single gene disorders (such as sickle cell disease), or gene rearrangements that can lead to pregnancy loss and birth defects;
- We use three specific types of PGT, which is a new term and includes the same functions as the more familiar Preimplantation Genetic Diagnosis (PGD) and Preimplantation Genetic Screening (PGS) embryo genetic tests;
- Embryologists use PGT to diagnose embryos that are genetically defective during IVF and will not be used and transferred to a woman’s uterus for pregnancy.
The process begins with in vitro fertilization (IVF), when an egg and sperm are fertilized in a laboratory to create embryos. The embryo is then cultured to the blastocyst stage (which is day 5-6 of embryo development). An embryologist takes a small portion of cells from each embryo and analyzes the DNA of the embryos in a genetics laboratory to detect genetic abnormalities. Only healthy embryos are then used for embryo transfer.
There are several types of PGT, each of which focuses on the study of a specific goal:
- PGT-A tests chromosomes for aneuploidy.
- PGT-M focuses on detecting specific genetic diseases.
- PGT-SR determines specific structural rearrangements of DNA.
PGT-A is a genetic analysis of the embryo to determine if it has a normal amount of chromosomes. As a result of unequal division of sperm or egg, the embryo may have too few or too many chromosomes.
Most people have 46 chromosomes, inheriting 23 from each parent. If the embryo is missing a chromosome or has an extra chromosome, it is called aneuploidy. Monosomy means one missing chromosome, while trisomy means one extra chromosome.
A child can survive only in the case of one type of monosomy – if one of the X chromosomes is missing or damaged. This disease is called Turner syndrome. One of the most well-known diseases in the case of chromosomal trisomy is Down syndrome (trisomy of chromosome 21), Edwards syndrome (trisomy of chromosome 18) and Patau syndrome (trisomy of chromosome 13).
Aneuploidy is one of the main causes of implantation failure and miscarriage, as well as the main cause of congenital diseases.
In addition to the health benefits, PGT-A can also provide an economic and emotional solution for couples undergoing IVF. Avoiding unsuccessful pregnancy attempts and complications can save both significant financial resources and protect against emotional experiences.
PGT-A is recommended to:
- For couples who have previously had an aneuploidy pregnancy;
- Women who have had two or more miscarriages;
- Women who have previously had an unsuccessful embryo implantation;
- Women diagnosed with unexplained infertility;
- For women over 35 years old;
- For women who have had repeated unsuccessful infertility treatments.
(PGT-M) can be offered to couples who want to avoid the risk of transmitting hereditary genetic diseases to their child.
PGT-M is a method used to evaluate embryos for genetic diseases and chromosomal abnormalities. PGT-M diagnoses specific gene mutations carried by one or both parents. The embryo is biopsied, during which some cells are taken. Next, they are checked in a genetics laboratory to see if the embryo has passed on an already known genetic disease in the family.
PGT-M can be used to look for single gene disorders (inherited diseases caused by a single gene). After the analysis, healthy embryos can be transferred to the uterine cavity. In this way, it is possible to avoid the inheritance of genetic diseases.
How to find out if there is a risk of monogenic diseases?
It is important to remember that monogenic diseases can be passed on from older children. However, not all monogenic diseases affect all family members, and the risk of transmission depends on genetic analysis and family history of disease. If the tests confirm the transmission of monogenic diseases, the couple should consult a geneticist to analyze the risks. A clinical geneticist will help to understand the genetic predisposition, answer questions and participate in the development of an individual action plan.
Who is it good for?
PGT-M is mainly used in individuals/couples who are at high risk of transmission of hereditary diseases.
PGT-M tests for common ailments including:
- Renal polycystosis;
- Haemophilia;
- Huntington’s disease;
- Sickle cell anemia;
- Muscular dystrophy;
- Cystic fibrosis;
- BRCA1 and BRCA2 mutations;
- Fragile X syndrome;
- Tay-Sachs disease;
- Amyotrophic lateral sclerosis (ALS) is inherited in 5-10% of cases and is associated with mutations in certain genes.
Advantages of PGT-M:
- Improves IVF success rate – genetically healthy embryos have a higher chance of implanting and giving birth to healthy children.
- Reduces the risk of passing on hereditary diseases – PGT-M allows individuals/couples with a known hereditary disease to have a child who is unlikely to have the hereditary disease.
PGT-SR analyzes embryos from patients with known chromosomal structural rearrangements, such as inversions or translocations. These patients are at greater risk of having children with altered genetic material. Recurrent miscarriages are common in patients with these problems.
The PGT-SR tests for disorders including:
- Robertsonian translocations;
- Reciprocal translocations;
- Inversions.
By choosing PGT with SR, expectant parents can enjoy the emotional relief of knowing that they are doing everything they can to prevent genetic abnormalities from being passed on to their children.
When and why?
In today’s world, where patients are provided with a wide range of information and options, making informed decisions about their family’s health and future is becoming more and more important. During several IVF attempts with PGT-A, potential parents are sometimes faced with the situation that none of the embryos have the correct set of chromosomes. This is the moment when it is extremely important to make a decision – to continue trying or to look for alternative ways. One of the alternatives is the use of donor germ cells (gametes). However, the choice of a donor can be difficult, considering that the germ cells of both parents are involved in the formation of the embryo. In such situations, the PGT-Complete analysis comes to the rescue, providing information about aneuploidy and helping to make informed decisions.
Aneuploidy or changes in the number of chromosomes can even be the reason for failed IVF attempts or genetic abnormalities in the child. The PGT-Complete analysis helps to find out from which parent the abnormal division of chromosomes originated, and it helps to understand the possible causes of aneuploidy and to make informed next steps.
PGT-Complete test takes PGT-A beyond aneuploidy testing, to provide a new standard of care with the most clinically comprehensive insights.
- PGT-A – All the benefits of our innovative and proprietary AI to improve the chances of IVF success;
- Parental QC – Providing patients reassurance that the intended egg and sperm were used, to help reduce parental anxiety of potential mix-ups;
- Genetic PN check – Providing the capability to identify and rescue true 2PN embryos from morphologically identified 0, 1, and 3PN embryos, to confidently enable additional euploid embryo transfers;
- Origin of aneuploidy – Supporting the clinic and patient, by identifying the origin of abnormality, to guide future decisions.
The PGT-Complete test is becoming increasingly important in reproductive medicine, helping patients make informed decisions about the choice of germ cell donors. In the case of repeated unsuccessful IVF, the use of this test can become a successful key to pregnancy, as it provides information about the origin of aneuploidy and helps to choose the optimal method to get pregnant and give birth to a healthy child.