Preimplantation Genetic Testing
Preimplantation genetic diagnosis (PGD) is a very important diagnostic technique that allows us to detect genetic abnormalities in the embryo before its transfer to the mother’s uterus. To do so, an embryo cell needs to be collected to subsequently examine its genetic material.
Each cell in your body contains chromosomes, which contain your genetic material in genes. Within each cell there are thousands of genes. We inherit 23 pairs of chromosomes from our parents and genetic disease is caused by an abnormality of a gene or entire chromosome. These abnormalities include:
The human body prefers the exact number of genes, completely intact. If this is not the case, genetic abnormalities occur, which can lead to miscarriage or the birth of a child with a congenital disease or defect. Depending on the indication, the following genetic tests can be performed:
Aneuploidy test (PGT-A)
This test consists of examining the number of chromosomes in the embryo by applying NGS.
The transfer of embryos with genetic abnormalities may decrease the pregnancy rate and increase the percentage of miscarriages. Identifying these embryos improves the success rates in an assisted reproduction programme. Preimplantation genetic diagnosis (PGD) is recommended in those cases in which there is a chromosomal risk for the embryo, such as:
- Couples with recurrent miscarriages
- Women of advanced reproductive age
- Implantation failures
- Genetic male factor
Recent advancements in the field have shown that the use of PGT-A during IVF leads to an increase in implantation rates, which, in turn, result in higher pregnancy rates. It has also been shown to reduce the incidence of miscarriage by identifying chromosomally abnormal embryos that otherwise would have previously been transferred. Due to the mounting research in favor of routine genetic screening we have made PGT-A an integral part of all our IVF procedures.
Structural chromosome abnormalities
Occasionally we find healthy patients with abnormalities on their karyotype who only have problems when trying to achieve a pregnancy. Those patients who are carriers of balanced or Robertsonian translocations, as well as inversions, may generate abnormal embryos. In these cases, the Preimplantation Genetic Diagnosis (PGD) technique is recommended to identify the altered embryos and avoid their transfer.
Monogenic diseases (PGT-M)
Another type of abnormality are those that are caused by a single gene mutation. These abnormalities are not identifiable with karyotype and the specific DNA structure needs to be examined in order to identify them.
Transmission of certain genetic diseases through the parents can be avoided by applying Preimplantation genetic diagnosis (PGD) on the embryos collected during an assisted reproduction cycle. A few of these diseases are cystic fibrosis, beta thalassaemia or some muscle dystrophies.
PGT-M can be used by both fertile and infertile couples. Couples who are carriers of a familial single gene disorder may wish to access PGT-M to have children without the particular genetic disorder.