Pre-implantation Genetic Testing (PGT) allows us to test embryos before transfer.

For people with a chromosomal rearrangement, PGT-SR (Preimplantation Genetic Testing for chromosomal structural rearrangements) can be performed to improve the chance of establishing a healthy pregnancy.

Chromosome rearrangements

Chromosomal rearrangements are changes from the normal size or arrangement of chromosomes, which are the structures that hold our genetic material. People with chromosome rearrangements are at an increased risk of producing embryos with the incorrect amount of genetic material, which typically do not lead to a successful pregnancy.

The different types of chromosomes rearrangements
  • Translocations: in which segments of two chromosomes break off and change places
  • Inversions: in which a segment of a chromosome has reversed orientation
  • Deletions: in which a segment of a chromosome is missing
  • Duplication: in which there is an extra segment of a chromosome
  • Insertion: where a segment of a chromosome has been inserted into the incorrect location

The goal of PGT-SR

The goal is to achieve a pregnancy that is unaffected by a structural chromosomal abnormality (translocation). Chromosome rearrangements can be inherited or can happen spontaneously. Many carriers of balanced chromosome rearrangements are healthy and are unaware of their carrier status until they try to have children. Carriers of balanced rearrangements are at risk of producing embryos with the incorrect amount of chromosomal material, these embryos usually do not lead to a successful pregnancy.

PGT-SR can help identify embryos with the correct amount of chromosomal material that are most likely to lead to a successful pregnancy and healthy live birth.

How does PGT-SR work?

PGT-SR involves testing embryos created through IVF and then transferring only chromosomal correct embryos.

If a parent has an unusual chromosome rearrangement will it always be passed on?

Not necessarily, there are several possibilities for each pregnancy:

  • The child may inherit an entirely normal chromosome arrangement.
  • The child may inherit the same chromosome rearrangement as the parent.
  • The child may be born with a learning disability, developmental delay, and/or health problems.
  • The pregnancy may end in miscarriage.

Therefore, it is usually possible for a person who carries a chromosome rearrangement to have healthy children, and many do. As each rearrangement is unique, carriers would have to discuss their particular situation with a genetic specialist. A child can be born with a rearrangement although both parents’ chromosomes are normal. This is called a de novo or new rearrangement.

Next steps

If you would like to arrange a consultation, you can contact our Genomics team on 0800 564 2270. Or you can complete a self referral form here.