PGT-SR - Preimplantation Genetic Testing in HSR Layout, Bangalore

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.

For people with a chromosomal rearrangement, PGT-SR, or preimplantation genetic testing for chromosomal structural rearrangements, can be performed to improve the chance of establishing a healthy pregnancy. PGT-SR involves testing embryos created through in vitro fertilization (IVF) and then transferring only normal embryos. PGT-SR was formerly known as PGD, preimplantation genetic diagnosis.

What is a chromosomal structural rearrangement?

Chromosomes are the structures that house the genetic material that directs our growth and development. When a structural rearrangement occurs, the chromosomes are altered in such a way that their normal rearrangement or size changes. Your chromosomes can undergo rearrangements that include the following:

Duplications: A segment of the chromosome is repeated

Deletions: A segment of the chromosome is missing

Inversion: A segment of chromosome reverses its orientation

Translocation: A segment of the chromosome changes its location. Two different types of translocations are observed.

Inversions

Inversions occur when a segment of chromosome is flipped and reinserted upside down inside the chromosome. The two types of inversions observed are paricentric and paracentric inversions. Paricentric inversions involve the centromere while paracentric inversions do not. Embryos created by a person with an inversion may have missing or duplicated chromosome material.

Reciprocal Translocations

A reciprocal translocation occurs when two different segments of genetic material break off from their chromosomes and swap places. When this occurs and there is no net gain or loss of genetic material, the translocation is balanced. If this same exchange occurs and there is a net gain or loss in genetic material, the translocation is unbalanced. People that are carriers of a balanced translocation can have children with either the same balanced translocation, an unbalanced translocation, or a normal set of chromosomes.

Robertsonian Translocations

A Robertsonian translocation occurs when two different chromosomes join to form one large chromosome. This results in an abnormal chromosome count of 45 instead of the normal 46. The most seen Robertsonian translocations are between chromosomes 13/14 and 14/21.

Who is PGT-SR for?

PGT-SR is appropriate for people who have a chromosome rearrangement, and thus are at risk of creating embryos with the incorrect chromosome number or structure. You may consider PGT-SR for chromosome rearrangements if you had a child or pregnancy with a chromosome rearrangement or if you or your partner are a carrier of an:

1. Inversion

2. Reciprocal translocation

3. Robertsonian translocation.

The PGT-SR Process

Once your fertility specialist or genetic counsellor determines PGT-SR is appropriate, The Genomic Centre will conduct a review of your translocation or inversion.

After undergoing a personalised IVF cycle and creating your embryos , the embryo biopsy samples are then sent to genetic laboratory where PGT-SR testing is conducted. PGT-SR screens out embryos that carry unbalanced translocations, ensuring only those with the correct amount of genetic material are selected for transfer.