Preimplantational
Genetic Diagnosis treatment
What does it mean?
The Preimplantational Genetic Diagnosis (PGD) is a method of prenatal diagnosis that is performed on the embryo before its transfer to the uterus. In case of women/couples with the risk of transmitting chromosomal or genetic alterations to the descendants, the PGD provides information on the condition of each embryo, thus making it possible to select only the healthy embryos for the transfer to the uterus. The method of PGD is the combination of: - The in vitro fertilization.
- The biopsy of embryonary cells through micromanipulation.
- Technique of cytogenetical and molecular diagnosis.
When is it advisable?
When there is a risk that the embryos suffer serious alterations in the number and structure of their chromosomes (study of aneuplody through FISH) or an alteration in the gene that is the cause of(monogenic disease), Also, when due to their ascendants, there are well-grounded doubts about the viability of the embryos.
Procedure
1. Preliminary phase.
In this phase, genetic examinations are performed on the parents who are carriers of certain diseases in order to gather all the necessary information before the application of PGD.
2. Obtaining the embryos.
This phase consists of obtaining those embryos that will be subjected to the diagnosis. They have to be produced “in vitro” through an assisted reproduction treatment, in spite of the fact that the couple does not suffer from any reproduction disorder that prevents them from the natural procreation. That’s why the embryos cannot be obtained by uterine lavage.
3. Embryonary biopsy.
The embryonary biopsy is performed 3 days after diagnosing the fecundation, when the embryo already consists of 6-8 cells. During the intervention, one or two cells are extracted from the embryo without endangering its normal development. After the biopsy took place, the embryo is returned into the incubator where it’s kept in a culture until the results of the diagnosis arrives and the date of its possible transfer can be estimated.
4. Gene diagnostic analysis
The obtained biopsy is analysed and subjected to genetic studies in a reference laboratory.
5. Transfer of embryos.
Once we have the results of the genetic analysis, it’s decided together with the couple, which embryos, with normal chromosome structure and character of viability, will be transferred.
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