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.