Genetic IVF

Preimplantation Genetic Testing (PGT) refers to the technique used as part of an in vitro fertilization (IVF) cycle to analyze the genetic makeup of the embryos prior to their transfer into the uterine cavity.

1. PGT-A (Preimplantation Genetic Testing for Aneuploidies), formerly known as PGS (Preimplantation Genetic Screening) is used to detect abnormalities in the number of chromosomes in the embryos. PGT-A allows to screen for chromosomal aneuploidy that can cause disorders such as Down syndrome (trisomy 21, Turner syndrome (45, XO) and Klinefelter syndrome (47, XXXY)… It also allows to screen for partial aneuploidies, unbalanced translocations and polyploidies. Following PGT-A, only the best euploid embryos are transferred, theoretically decreasing the risk of miscarriage and increasing the pregnancy and live birth rates.
There are many indications for PGT-A, including couples with a history of recurrent miscarriages or recurrent implantation failure with IVF, couples with a previous pregnancy with chromosomal abnormalities, carriers of numerical abnormalities of chromosomes, and women with advanced age.

2. Preimplantation Genetic Testing for monogenic/single gene disorder (PGT-M), formerly known as PGD (Preimplantation Genetic Screening) is used to detect single mutations in the embryos. These single gene mutations can cause several types of hereditary diseases that can be autosomal dominant such as Huntington disease, autosomal recessive such as cystic fibrosis, or X linked such as Hemophilia or Fragile X syndrome… PGT-M is indicated in couples in which one of the partners has a genetic disorder, couples in which both partners are carriers of the same autosomal recessive disorder, couples with a previous child or pregnancy with a single gene disorder, and couples in which one of the partners has a mutation linked to a hereditary cancer syndrome, such as BRCA1 and 2.

3. Preimplantation genetic testing for structural rearrangements (PGT-SR) is used to detect abnormalities in the size or arrangement of chromosomes in the embryos. There are several types of structural rearrangements, that can be balanced or unbalanced, such as translocations, inversions, deletions, duplications… PGT-SR is indicated for couples in which one of the partners is a carrier of a chromosomal structural rearrangement, and in couples with a previous child or pregnancy with a structural rearrangement.

PGT is performed as part of an IVF/ICSI cycle, and therefore includes the following steps:
• Controlled Ovarian Stimulation.
• Oocyte Retrieval (Egg collection)
• In vitro Fertilization with ICSI
• Embryo culture.
• Embryo biopsy.
• Transfer of chosen embryos.
• Luteal phase and pregnancy test.
• Cryopreservation of chosen embryos.
• Frozen embryo transfer

A laser is used to create an opening in the outer shell of the embryo, and cells are taken for genetic analysis. The number of cells taken depends on the stage at which the embryo is biopsied (day 3 or day 5 of development, depending on the case and indication). When performed by experienced operators, the biopsy does not harm the embryo and does not decrease the chances of implantation and pregnancy.
Depending on the stage at which the biopsy is performed (Day 3 or 5), and the availability of the genetic result, the embryos free from disease can be transferred in the same cycle, or frozen by vitrification for transfer in an another cycle.