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Preimplantation Genetic Testing2019-11-07T21:08:13+00:00

PREIMPLANTATION GENETIC TESTING

Aneuploid Embryos & Preimplantation Genetic Testing

Aneuploid Embryos & Preimplantation Genetic Testing

Aneuploidy is the term associated with an abnormal number of chromosomes found in a cell within an early human embryo.  This term literally means not or without the correct number of chromosomes.  A genetically normal embryo is made up of cells that each contain 46 chromosomes, numbered 1-22 (autosomes) plus the sex chromosomes X and Y. Embryos with the correct number of chromosomes are also called euploid embryos.  Unfortunately, aneuploid embryos do not physically look any different than euploid embryos so without preimplantation genetic testing for aneuploidy (PGT-A), aneuploid embryos can and will be transferred and these embryos have been shown to fail implantation in about 96% of the cases1. It is therefore important to identify and selectively transfer euploid embryos which have been shown to have a very high chance of successful implantation and pregnancy.

As the graph (right) shows2, the incidence of embryo aneuploidy increases with maternal age from approximately 30% at age 30-34 up to almost 80% at age 41-42!  This is a major reason for the decreasing expectation of live birth per treatment cycle associated with maternal age. In this same chart you will notice that implantation rate does not decrease with maternal age when selectively transferring euploid embryos during IVF cycles.

  • PG-Seq Rapid Non-Invasive PGT Kit
    Optimized to test DNA from spent embryo culture media or blastocoelic fluid samples for non-invasive Preimplantation Genetic Testing.

  • PG-Seq™ Rapid Kit
    Accurately detects whole chromosome aneuploidy along with structural rearrangements such as unbalanced translocations and segmental errors from biopsies, with sample preparation taking only 3 hours using an efficient, streamlined workflow.

  • PG-Seq Kit 2.0
    An NGS workflow solution for PGT-A (Preimplantation Genetic Testing for Aneuploidy) and PGT-M (Preimplantation Genetic Testing for Monogenic Disorders) which includes the DOPlify® WGA kit, a library preparation kit which is used to prepare the WGA product for next generation sequencing and proprietary PG-Find software used to analyze the genome for chromosome aberrations as small as 5 MB.

PGT-A Rates

“More than 40% of healthy looking IVF embryos are aneuploid in women older than 35 years.”

Harton et al, Fert Steril Dec 2013, 100 (6): 1695-703

Preimplantation Genetic Testing-Aneuploidy

As this graph shows3, PGT-A and selective transfer of euploid embryos out performs no PGT-A as it relates to live birth rates.  Without PGT-A, implantation and pregnancy rates drop significantly as the female partner’s age increases.  In this data set, PGT-A cycles had a statistically significant increased pregnancy outcome for every age group compared to cycles without PGT-A.

Babies Transferred Embryos

The most significant recent advance to improve IVF success rates has been the introduction of 24 chromosome preimplantation genetic testing-aneuploidy (PGT-A).

The purpose of PGT-A is to identify embryos with the correct number of chromosomes for IVF transfer. PGT-A cannot correct aneuploid embryos; it can only identify those embryos that are not suitable for transfer.

Selecting only euploid embryos to transfer with PGT-A has been demonstrated to:

  • Reduce the time to pregnancy by reducing the number of cycles/transfers needed to become pregnant
  • Reduce the risk of miscarriage
  • Allow only the selection of euploid embryos for freezing, avoiding the expense of storing embryos unsuitable for transfer
  • Overcome the adverse effect of maternal age on IVF success by focusing on euploid embryos
  • Reduce the risk of multiple pregnancies from IVF

“PGS can increase the clinical pregnancy rate by around 50%.”

Yang et al. Molecular Cytogenetics 2012, 5: 24.

For research use only. Not for use in diagnostic procedures.

  1. Comprehensive chromosome screening is highly predictive of the reproductive potential of human embryos: a prospective, blinded, nonselection study. Scott RT Jr, Ferry K, Su J, Tao X, Scott K, Treff NR. Fertility and Sterility 2012 Apr:97(4):870-5
  2. Diminished effect of maternal age on implantation after preimplantation genetic diagnosis with array comparative genomic hybridization. Harton GL, Munné S, Surrey M, Grifo J, Kaplan B, McCulloh DH, Griffin DK, Wells D; PGD Practitioners Group. Fertility and Sterility 2013 Dec;100(6):1695-703
  3. McCulloh D., 8th Annual Southwestern Embryology Summit, 2019. Mesa, AZ
  4. Selection of single blastocysts for fresh transfer via standard morphology assessment alone and with array CGH for good prognosis IVF patients: results from a randomized pilot study. Yang Z, Liu J, Collins GS, Salem SA, Liu X, Lyle SS, Peck AC, Sills ES, Salem RD. Molecular Cytogenetics 2012 May 2;5(1):24