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PGD TRS™
PGD NGS for translocations
What is PGD TRS™?
PGT-SR for structural rearragements consists in the examination of the embryo’s genetic material for the presence of abnormal fragments or entire chromosomes involved in translocation.
It has to be stressed that carriers of chromosomal translocation are also exposed to higher risk of disorders in the number of other chromosomes, unrelated to chromosomes involved in translocation. It is recommended to complement the PGD TRS targeting the chromosomes involved in translocation with the comprehensive diagnosis for aneuploidies in all chromosomes – PGS NGS 360.
PGD TRS™ preimplantation testing allows examining the cells collected from embryos for the presence of abnormalities resulting from balanced reciprocal
translocations in parents. This testing technique is adapted to the needs of a given patient.
Translocation means the movement of a fragment of genetic material from one chromosome to another. Most often, the altered arrangement of the genetic material on chromosomes is inherited from one of the parents.
In the case of balanced translocation, the genetic material is not lost or in excess, but only has altered location, e.g. fragments of two or more chromosomes change places,
or chromosomes join each other. A carrier of a balanced translocation produces abnormal reproductive cells, thus preventing pregnancy, causing miscarriages or disease syndromes with chromosome abnormalities as the underlying cause.
1:500
One of 500 individuals carries
chromosomal translocations
Why is it worth to perform PGD TRS™?
- Most reproductive cells of the translocation carrier are abnormal, which causes poorer prognosis for fertilisation and development of healthy children. PGD TRS allows selecting normal embryos, thus significantly reducing the risk of reproductive failure.
- PGD TRS allows checking for the occurrence of a “de novo” abnormality of the genetic material number in the embryo.
- Preimplantation diagnosis reduces the risk of miscarriages and increases chances for giving birth to a healthy child.
The first in the world use of NGS (Next Generation Sequencing) technology in the clinical practice in preimplantation diagnosis for translocations.
INVICTA Genetic Laboratory: August 2013
Figure 1. Chances for pregnancy with the use of PGD TRS™
Figure 2. 32 possibilities of the genetic material distribution in the reproductive cells produced by the balanced translocation carrier.
What are the indications for PGD TRS™
Confirmed presence of a translocation in an individual trying for a child.
INVICTA Genetic Laboratory provides:
- Specialist Collection Kit INVICTA PGD BIOPSY KIT™
- Free transport
- Online access to the results
INVICTA Genetic Laboratory provides:
- Specialist Collection Kit INVICTA PGD BIOPSY KIT™
- Free transport
- Online access to the results
Limitations
The test provides information on the status of chromosomes involved in translocation. The test does not determine the status of other chromosomes. The absence of lost or extra fragments in chromosomes involved in translocations does not exclude the presence of changes in the number or structure of other chromosomes. The probability of detecting derivative regions of translocations depends on the location of the points of breakage on chromosomes and on the size of regions being subject to translocation. The type of technique used in the test is determined depending on the individual situation of a given patient with confirmed translocation. Techniques other than NGS may be applied in the test if the patients’ situation so requires. The NGS technique for this test has been validated for detecting genetic material losses or gains involving a fragment larger than 5 Mpz in the material constituting blastocyst cells. The reliability of this technique is lower in case of translocations where breakage regions are located near telomeres or centromeres.
Literature
- 1. Łukaszuk K, Pukszta S, Ochman K, Cybulska C, Liss J, Pastuszek E, Zabielska J, Woclawek-Potocka I. Healthy Baby Born to a Robertsonian Translocation Carrier following Next-Generation Sequencing-Based Preimplantation Genetic Diagnosis: A Case Report. AJP Rep. 2015 Oct;5(2):e172-5.
- 2. Łukaszuk K, Pukszta S, Wells D, et al. Routine use of next-generation sequencing for preimplantation genetic diagnosis of blastomeres obtained from embryos on day 3 in fresh in vitro fertilization cycles. Fertil Steril 2015;103:1031–6.
- 3. Munné S, Sandalinas M, Escudero T, et al. Outcome of preimplantation genetic diagnosis of translocations. Fertil Steril 2000;73:1209–18.
- 4. Verlinsky Y, Tur-Kaspa I, Cieslak J, et al. Preimplantation testing for chromosomal disorders improves reproductive outcome of poor prognosis patients. Reprod Biomed Online 2005;11:219–25.
- 5. Fischer J, Colls P, Escudero T, et al. Preimplantation genetic diagnosis (PGD) improves pregnancy outcome for translocation carriers with a history of recurrent losses. Fertil Steril 2010;94:283–9.
- 6. Gianaroli L, Magli MC, Ferraretti AP, Munne S, Balicchia B, Escudero T, Crippa A. Possible interchromosomal effect in embryos generated by gametes from translocation carriers.Hum Reprod 2002;17:3201–3207.
- 7. Fiorentino F, Kokkali G, Biricik A, et al. Polymerase chain reaction based detection of chromosomal imbalances on embryos: the evolution of preimplantation genetic diagnosis for chromosomal translocations. Fertil Steril 2010;94:2001–11.
- 8. Rabinowitz M, Ryan A, Gemelos G, Hill M, Baner J, Cinnioglu C, et al. Origins and rates of aneuploidy in human blastomeres. Fertil Steril 2012;97:395–401. Traversa MV, Carey L, Leigh D. A molecular strategy for routine preimplantation genetic diagnosis in both reciprocal and Robertsonian translocation carriers. Mol Hum Reprod 2010;16:329–37.
- 9. Yin X, Tan K, Vajta G, Jiang H, Tan Y, Zhang C, et al. Massively parallel sequencing for chromosomal abnormality testing in trophectoderm cells of human blastocysts. Biol Reprod 2013;88:1–6.
- 10. Lim CK, Cho JW, Song IO, Kang IS, Yoon YD, Jun JH. Estimation of chromosomal imbalances in preimplantation embryos from preimplantation genetic diagnosis cycles of reciprocal translocations with or without acrocentric chromosomes. Fertil Steril 2008;90:2144–2151.
- 11. Traversa MV, Carey L, Leigh D. A molecular strategy for routine preimplantation genetic diagnosis in both reciprocal and Robertsonian translocation carriers. Mol Hum Reprod 2010;16:329–337.
- 12. Fiorentino F, Spizzichino L, Bono S, et al. PGD for reciprocal and Robertsonian translocations using array comparative genomic hybridization. Hum Reprod 2011;26:1925–35.
- 13. Handyside AH. 24-Chromosome copy number analysis: a comparison of available technologies. Fertil Steril 2013;100:595–602.
- 14. Martín J, Cervero A, Mir P, et al. The impact of next-generation sequencing technology on preimplantation genetic diagnosis and screening. Fertil Steril 2013;99:1054–61.
- 15. Wells D, Kaur K, Grifo J, et al. Clinical utilization of a rapid low-pass whole genome sequencing technique for the diagnosis of aneuploidy in human embryos prior to implantation. J Med Genet 2014;51:553–62.
- 16. Le Caignec C, Spits C, Sermon K, et al. Single-cell chromosomal imbalances detection by array CGH. Nucleic Acids Res 2006;34:e68.