PGT-SR Testing

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 aim of PGT-SR

The aim is to achieve a pregnancy that is unaffected by a chromosome imbalance due to the inherited structural rearrangement/translocation.

Chromosome rearrangements can be inherited or can happen spontaneously (de novo). 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.

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.

The first step is to contact the PGT team at Care with a copy of your chromosome result to perform the initial check that imbalances arising from the translocation can be detected at the embryo stage.

If you are eligible for NHS funded treatment – please contact your local genetics service and request a referral to Care Fertility Nottingham.

If you are considering PGT privately funded treatment speak with your Insurance provider in the first instance as they may be able to provide more information about financial assistance.