Preimplantation Genetic Testing for carriers of genetic disorders
What is Preimplantation Genetic Testing for carriers of genetic disorders?
In carriers of genetic disorders, preimplantation genetic testing (PGT) is a diagnosis method of an inherited condition on the embryo during an IVF treatment, before they are implanted in the womb. It allows selecting and transferring to the patient only the embryos that are free from a specific inherited disorder.
Only when the genetic disease or chromosomal rearrangement is identified and fully characterized in the family, the PGT-M or PGT-SR can be offered.
How is it performed?
- In case of single gene disorders, the test is family-specific, thus a previous set-up test before starting the IVF cycle should be performed. Blood samples from the couple and other family members are required. A report is issued by PGDlabs when the set-up test is completed.
- In Vitro Fertilization cycle to obtain embryos performed in an Assisted Reproduction unit.
- Embryo Biopsy: can be performed on day 3 or Day 5 of embryo development and consists of removing one cell (day 3) or small groups of cells (day 5) from the embryo without compromising its normal development.
- Genetic Testing: the cell or cells obtained from the embryo are processed for genetic analysis by PGDlabs team. The test, performed by Sanger Sequencing, allows us to determine those embryos that are carriers of the genetic disease with an overall 98-99% of accuracy. Additionally, aneuploidy screening (PGT-A) can be performed on the embryos.
- Embryo Transfer: The results of the genetic test are transmitted to the assisted reproduction unit and the embryos that are not at risk of developing the genetic condition are transferred.
Who can benefit with the Preimplantation Genetic Diagnosis?
Couples at risk of transmitting an inherited disease to their offspring. Preimplantation Genetic Diagnosis helps these couples identify embryos carrying the specific genetic disease (PGT-M) or a chromosome abnormality (PGT-SR). This method can be used to screen embryos in families affected by:
- A single gene disorder. The genetic condition can be transmitted to the offspring in different inherited patters:
- Autosomal recessive (both members of the couple are healthy but carriers of a specific genetic mutation. Their risk of having an affected child is 25%)
- Autosomal dominant (one member of the couple is an affected carrier of a mutation. The risk of having an affected child is 50%)
- X-linked (the most common form is when a healthy mother is carrier of a mutation in one of her chromosomes X that can be transmitted to 50% of her children)
- Chromosomal rearrangement (reciprocal translocation, inversions, etc): One or both members of the couple could be healthy carriers of a balanced chromosomal rearrangement. The couple is at risk of having children with unbalanced forms of the rearrangement, leading to monosomies and trisomies that can be related to pregnancy failure, miscarriage or chromosomally abnormal live birth. Embryo testing can be done by different technologies such as FISH, aCGH or NGS.
- Couples with an affected child that needs HLA matching
