PGT-SR Specialist

PGT-SR Preimplantation Genetic Testing for Structural Rearrangements

Our most advanced test designed for couples where one or both of the partners carries a known balanced structural rearrangement in their chromosomes

Overview

PGT-SR
How does it work?
PGT-SR Plus
Indications
Benefits
Test limitations

What is PGT-SR?

The Preimplantation genetic testing for Structural Rearrangements (PGT-SR), is a test performed on embryo biopsies to screen embryos for chromosomal imbalances (extra or missing chromosome material) resulting from a parental structural rearrangement.
In addition to screening for imbalances resulting from a parental structural rearrangement, PGT-SR also detects numerical chromosome abnormalities (aneuploidies). PGT-SR would be able to detect all of the same chromosome imbalances that would be assessed by PGT-A.

What is a Balanced Structural Rearrangement?

A balanced structural rearrangement, such as translocation or inversion, involves a change in chromosome structure without gains or losses in chromosome material.
A translocation is a type of chromosomal rearrangement that occurs when genetic material is exchanged between two chromosomes. An inversion occurs when a chromosome segment is flipped within the chromosome.

Typically, a balanced structural rearrangement does not cause health concerns in carriers. However, a carrier of a balanced rearrangement has a higher risk of producing embryos with an unbalanced structural rearrangement (gain and/or loss of chromosome segments), which may lead to infertility, failed implantation, pregnancy loss, or the birth of a child with developmental delays and multiple congenital anomalies.
Children who inherit the balanced structural rearrangement from their carrier parent are not expected to have health concerns.
PGT-SR increases the probability of selecting a chromosomally normal (without the parental chromosomal rearrangement) or balanced (with the same parental chromosomal rearrangement) embryo for transfer, thus leading to improved assisted reproduction techniques (ART) outcomes.

PGT-SR can be used for different types of structural rearrangements including:

Balanced reciprocal translocation:

Occurs when segments from two chromosomes have been broken and exchanged. Each chromosome in the pair now has a segment of material from the other chromosome, in place of the original segment without gains or losses in genetic material.

Inversion:

Occurs when a segment within the chromosome has ‘flipped over,’ and is now in an inverted orientation.

Robertsonian translocation:

This is a specific type of translocation, which occurs between acrocentric chromosomes (i.e. chromosomes 13, 14, 15, 21, and 22). Instead of swapping segments, the long arm of the two chromosomes fuse together to form a single chromosome.

In order to determine whether PGT-SR can be offered, Igenomix will need to review the karyotype confirming the specific rearrangement that a member of the couple carries. The ordering provider should submit the karyotype report to Igenomix for PGT-SR case review.
In rare cases, Igenomix may need to perform a preliminary analysis, to confirm PGT-SR is feasible. A DNA sample from the partner who carries the structural rearrangement would be required.
Once Igenomix has completed the case review and confirmed that PGT-SR can be offered, embryo biopsy samples can be sent to Igenomix for PGT-SR analysis. Probe development is not required.

Our innovative methodology integrates a custom and in-house Next-Generation Sequencing (NGS) technology with a sophisticated internally validated algorithm for bioinformatic analysis.
Screening for sporadic aneuploidies is also performed to identify embryos with numerical chromosome aneuploidies not associated with the parental chromosomal rearrangement. Since general aneuploidy screening is included, separate PGT-A testing is not required.

The MitoScore test can also be performed to identify embryos that could have a greater capacity for implantation.
Upon the completion of the testing, a detailed genetic report is generated and forwarded to your physician for further evaluation and discussion within 7 working days from receipt of samples.

PGT-SR Plus is our most advanced 4-in-1 genetic test that incorporates both NGS and SNP analysis to increase accuracy and confidence for embryo transfer. In addition to screening for imbalances detected by PGT-SR, PGT-SR Plus includes the following features:

Ploidy assessment:

PGT-SR Plus enables the detection of both haploidy and triploidy, ensuring the selection of embryos with the correct chromosome content.

In addition, PGT-SR Plus increases the number of viable euploid embryos available for transfer by detection true 2PN (diploid) embryos from 0PN, 1PN and 2.1/3PN embryos that may not otherwise be considered for transfer.

Cohort Check – Sibling QC:

Provides assurance that the tested embryos within a cohort are genetically related to each other.

Contamination:

Our testing process includes measures to detect both external cell DNA and maternal cell contamination increasing the accuracy and confidence of the testing process and significantly reducing the risk of misdiagnosis.

This analysis can reduce the risk of misdiagnosis and provide additional reassurance about the IVF process.

Who should consider PGT-SR?

PGT-SR is indicated for any couple in which one member has been identified to carry a balanced structural rearrangement, such as a:

Reciprocal translocation
Inversion
Robertsonian translocation

The presence of a structural rearrangement increases the risk of creating embryos with chromosomal imbalances.

PGT-SR may be indicated when other structural abnormalities, such as ring chromosomes, are identified in the patient. Evaluation of the karyotype by Igenomix is required.

Main benefits:

PGT-SR significantly reduces the likelihood of transferring an embryo with an unbalanced structural rearrangement, and therefore:

- Increases pregnancy rates per transfer:
  Selecting chromosomally normal embryos can increase the rate of pregnancy after transfer.
- Reduces miscarriage rate:
  The risk for chromosomal abnormalities in embryos is higher when one partner carries a balanced structural rearrangement. The risk for miscarriage is reduced if a euploid embryo is transferred.
- Increases the likelihood of having a healthy baby:
  Depending on the size of the resulting imbalances and the chromosomes involved, the presence of an unbalanced structural rearrangement could result in a baby with varying degrees of intellectual disability/birth defects.
- Reduces the time and use of resources:
  Increases the chances for successful transfer by selecting embryos with the highest reproductive potential, reducing the time and costs of extra transfer cycles.

The limitations of PGT-SR include:

The accuracy of this test is estimated to be 98%.
PGT-SR cannot detect chromosomal imbalances that are smaller than the detection threshold of 6MB.
PGT-SR and PGT-A cannot detect the balanced form of a structural rearrangement, in which there is no gain or loss of chromosome material. PGT-SR can only assess for unbalanced forms of a rearrangement.
PGT-SR and PGT-A cannot detect uniparental disomy (UPD).
PGT-SR and PGT-A do not directly assess for birth defects. There is a general risk of birth defects of 4-6% for any baby born following IVF treatment. Birth defects may be caused by genetic or non-genetic factors.
PGT-SR and PGT-A cannot detect single gene disorders, such as cystic fibrosis, sickle cell anemia, or Tay-Sachs disease.
PGT-SR and PGT-A do not assess for multifactorial conditions, such as autism, schizophrenia, or diabetes.

Documentation

PGT-SR Specialists’ documents

Clinical Sheet

Download

Scientific evidence

The impact of patient, embryo, and translocation characteristics on the ploidy status of young couples undergoing preimplantation genetic testing for structural rearrangements (PGT-SR) by next-generation sequencing (NGS). J Assist Reprod Genet. 2021 Feb; 38(2): 387–396. doi: 10.1007/s10815-020-02054-4

Optimized NGS Approach for Detection of Aneuploidies and Mosaicism in PGT-A and Imbalances in PGT-SR. Genes 2020 Jul; 11(7):724.

ESHRE PGT Consortium good practice recommendations for the detection of structural and numerical chromosomal aberrations. Hum Reprod Open. 2020; 2020(3): hoaa017. doi: 10.1093/hropen/hoaa017

The impact of balanced reciprocal translocation – 46,XX,t(7;17) (p13;q24) probably involving the SOX9 gene in the in vitro fertilization with own oocytes evaluated by preimplantation genetic testing or donated oocytes. JBRA Assist Reprod. 2019 Jan-Mar; 23(1): 68–71. doi: 10.5935/1518-0557.20180066

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PGT-SR Preimplantation Genetic Testing for Structural Rearrangements

Custom and validated in-house NGS technology

Proprietary Artificial
Intelligence algorithm

What is PGT-SR?

What is a Balanced Structural Rearrangement?

PGT-SR can be used for different types of structural rearrangements including:

Balanced reciprocal translocation:

Inversion:

Robertsonian translocation:

Ploidy assessment:

Cohort Check – Sibling QC:

Contamination:

Who should consider PGT-SR?

Main benefits:

Clinical Sheet

FAQs

Can we help you?

Igenomix and fertility

ERA

EMMA

ALICE

Igenomix is in the media

PGT-SR Preimplantation Genetic Testing for Structural Rearrangements

Custom and validated in-house NGS technology

Proprietary ArtificialIntelligence algorithm

What is PGT-SR?

What is a Balanced Structural Rearrangement?

PGT-SR can be used for different types of structural rearrangements including:

Balanced reciprocal translocation:

Inversion:

Robertsonian translocation:

Ploidy assessment:

Cohort Check – Sibling QC:

Contamination:

Who should consider PGT-SR?

Main benefits:

Clinical Sheet

FAQs

Can we help you?

Igenomix and fertility

Other services

ERA

EMMA

ALICE

Igenomix is in the media

Proprietary Artificial
Intelligence algorithm