Preimplatation Genetic Test (PGT)

What is the PGT Test?

The Preimplantation Genetic Test, also known as PGT, is a test undertaken in order to obtain genetic information from the embryo to study the apparent risk of a genetic abnormality.

The main objective of this test is to increase the rate of healthy newborns and to offer them the best possible quality of life. Early detection of any type of genetic alteration prevents, in any case, the transmission of any severe hereditary disease to the baby.

What is the law on Preimplantation Genetic Diagnosis (PGD) in Spain?

According to Law 14/2006 on Assisted Human Reproduction Techniques, PGD is authorised in order to select embryos for therapeutic purposes. Under this premise, two assumptions are established:

• The detection of serious hereditary diseases, of early onset and non susceptible to postnatal curative treatment
• The detection of alterations that could compromise the viability of the embryo and, therefore, result in implantation failure.

Which PGT variants can be analysed?

PGT-A for aneuploidy screening

The Preimplantational Genetic Test for fetal aneuploidy is better known as the test that makes it possible to find some type of numerical alteration in the chromosomes.

Some of the best known chromosomal diseases that can be detected thanks to this test are:

• Down syndrome
• Patau syndrome
• Edwards syndrome
• Turner syndrome
• Klinefelter syndrome

PGT-A indications

• Women of advanced childbearing age (around 40 years old)
• Women who have had a miscarriage or spontaneous abortion
• Presence of any numerical sex chromosome abnormality (X or Y) in one or both members of the couple
• Presence of any chromosomal numerical alteration in one or both members of the couple

PGT-M for monogenic disease screening

In this case, the Preimplantational Genetic Test to detect monogenic diseases, also known as Mendelian, studies the different alterations that a single gene can present (hence the prefix, “mono-”) and enables the possibility of detecting cases of:

• Sickle cell anaemia
• Cystic fibrosis
• Phenylketonuria
• Batten disease

PGT-M indications

• Presence of some type of genetic disease in one or both members of the couple
• Presence of some type of genetic disease or abnormality in the natural family of one or both members of the couple

PGT-SR for structural disease screening

Lastly, the Preimplantational Genetic Test to detect structural chromosomal abnormalities, as its name suggests, is the test that facilitates the detection of some type of alteration in the chromosomal structure.

Some of the most known chromosomal abnormalities, such as Prader-Willi Syndrome or Angelman Syndrome, are preventable thanks to this type of preimplantational genetic testing.

PGT-SR indications

• The presence of some type of structural chromosomal alteration or abnormality in one or both members of the couple

We wanted to take this aneuploidy test to a higher level with the PGT-COMPLETE, which is based on the aforementioned PGT-A, with two improvements from a clinical perspective:

• It can give an opportunity to embryos that initially show an abnormal number of pronuclei, which are the embryos that only showed 0, 1 or 3 pronuclei morphologically, and that ultimately reach the blastocyst stage, can be biopsied and analysed in order to find out whether or not they present chromosomal alterations, thus increasing the probabilities of having a greater number of euploid embryos. 
• It allows us to know the origin of the aneuploidy. It facilitates information on the contribution of each gamete to the aneuploidy, which is valuable information when considering donor gamete switching. 

Additionally, parental quality control is ensured, i.e. this technique reduces patients’ concerns by ensuring the filiation of their embryos, as it confirms the match between the embryo biopsy sample and the parental samples provided.

Benefits of the PGT-Complete

• Patented Artificial Intelligence avoids interpretation errors
• Increases the possibility of pregnancy
• 2PN embryo rescue
• Identifies aneuploidy origin
• Guarantees embryo filiation
• Improves embryo selection
• Avoids the transfer of embryos that will not be implanted
• Avoids the transfer of embryos that may cause miscarriages or births of children with different syndromes
• Reduces the time required to achieve pregnancy
• More affordable
• Helps psychological wellbeing