Preimplantation genetic testing for structural chromosomal rearrangements (PGT-SR)

Preimplantation Genetic Testing for Structural Rearrangements (PGT-SR) is offered to patients who, before IVF treatment, find out that one of the partners is a carrier of a balanced structural rearrangement, such as a translocation or inversion.

The carriers of balanced structural rearrangements present abnormalities in the structure of the chromosomes, without gains or losses in chromosomal material. The risk factors of being a carrier of a balanced translocation or inversion include unexplained male infertility (low sperm count), implantation failure, recurring miscarriages, and family history of having offspring born with abnormalities.

In carriers of balanced structural rearrangements, there is a risk of producing eggs and sperm with unbalanced chromosomal alterations which could be transmitted to the offspring. In general, a carrier of a balanced structural rearrangement does not have health problems, although in some cases they may have difficulty conceiving. The embryos of carriers of balanced structural rearrangements may present unbalanced structural rearrangements (gain or loss of a chromosome segment), which may lead to implantation failure, miscarriage, or children born

with mental and/or physical problems. If the children inherit the balanced structural rearrangement, they should not have health problems, just like their carrier parent(s).

The identification of embryos which have inherited an unbalanced structural rearrangement may help patients and clinicians to decide which embryos to transfer.