Preimplantational Genetic Diagnosis
With this diagnosis we can detect chromosomal anomalies in the embryo. It consists in the genetic study of embryos to ensure that only healthy embryos are transferred. The diagnosis is indicated for patients with chromosomal alterations and a family history of chromosomal alterations, thus preventing the transmission of hereditary illnesses. It is also indicated when the mother is over a certain age (35 years old or more), given that the probabilities of the foetus having chromosomal anomalies (mainly aneuploidies) are significantly higher. In this case we would be talking about diseases such as Down’s syndrome.
The technique itself consists in extracting two cells (blastomeres) from the embryo when it has 8 cells, that is, on the third day after fertilisation. These extracted cells are studied in an associated lab mainly using two techniques: Fluorescent In Situ Hybridisation (FISH) or by Polymerase Chain Reaction (PCR).
In a few hours we obtain the result of the genetic state of the embryos and, at that moment, those with normal chromosomes are transferred.