What is Preimplantation Genetic Screening?
Preimplantation Genetic Screening (PGS) is a test that examines chromosomal material of an in vitro fertilized (IVF) embryos before implantation. It involves removing one or more cells from an IVF embryo to test for numerical chromosomal abnormalities (aneuploidy). This screening method facilitates the selective implantation of embryos that have a normal number of chromosomes (Euploid Embryos).
- One in two human preimplantation-IVF embryos are chromosomally abnormal.1
- Up to 40% of morphologically normal embryos harbor aneuploidies.2
-  McCoy RC. Mosaicism in Preimplantation Human Embryos: When chromosomalabnormalities are the norm. Trends Genet. 33(7): 448–463 (2017).
-  Harton GL, Munne S, Surrey M, et al. Diminished effect of maternal age on implantation afterpreimplantation genetic diagnosis with array comparative genomic hybridization. Fertil Steril.2013;100(6):1695–1703.
What are the common conditions that PGS can detect?
- Turner Syndrome
- Klinefelter Syndrome
- Down Syndrome
- Edwards Syndrome
- Patau Syndrome
- Other trisomies and monosomies that increase the risk of implantation failure and miscarriage
- Segmental Gain and Losses (>20Mb) in chromosomes which can lead to abnormalities in the embryo
Why do you need the PGS test?
- Reduces the number of IVF cycles required to achieve a successful pregnancy. 73% pregnancy rate with PGS vs 36% without using PGS$
- Increases success rate for single embryo transfer
- Reduces the likelihood of miscarriage due to Aneuploidies
- Increases reproductive success rates in women above 35 years
- $: Majumdar G, Majumdar A, Lall M, Verma IC, Upadhyaya KC. Preimplantation genetic screening for all 24 chromosomes by microarray comparative genomic hybridization significantly increases implantation rates and clinical pregnancy rates in patients undergoing in vitro fertilization with poor prognosis. J Hum Reprod Sci 2016;9:94-100
When can the PGS test be done?
After fertilisation when the embryo is 3 to 5 days old. At this stage, there are sufficient number of cells from which DNA can be isolated,thus ensuring success of the test. Mosaicism of Aneuploidies can be detected at this stage Vitrification (rapid-freezing) of embryos after biopsy also allows the clinician todetermine the optimum conditions for implantation
Who needs to get tested?
- Couples undergoing IVF
- Patients at any age who have repeated implantation failure or recurrent pregnancyloss while undergoing IVF
- Women over 35 years old undergoing IVF
- Couples with recurrent miscarriages
- Positive history of chromosomal abnormalities in the family
- Diagnosed carriers of chromosomal aberrations
Why Claria PGS is better?
- Sequencing based PGS lead to higher resolution and detects segmental deletions and duplications
- Robust sequencing technology that provides sensitive and replicable results
- CAP proficiency testing passed
- Inherent flexibility to suit your needs without any compromise on quality.
- We provide end-to-end support: From site validation and embryo biopsy training, to result data interpretation, phenotype correlation and genetic counselling
What is the technology that Claria PGS uses?
Claria PGS is carried out using advanced Next- Generation Sequencing (NGS) technology
What are the advantages of NGS based techniques?
- Rapid and convenient
- Screening of all 23 pairs of chromosomes for abnormalities in one test
- Able to detect greater than 20 Mb gains and losses in chromosomes
- Higher resolution – 1Mb areas are analysed to provide data with high confidence
- High sensitivity in detecting Aneuploidy (100 % sensitivity)
- High specificity and accuracy (99.98% specificity)
- Lower chances of test failure with NGS
Advantages of PGS by NGS vs. other screening approaches
|Fluorescent In Situ Hybridisation (FISH)||Array Comparative Genomic Hybridisation (aCGH)||Single Nucleotide Polymorphism (SNP) Microarray||NGS|
|A largely manual process, highly skill/operator dependant.||Requires normal DNA for each sample to provide a comparison. A prolonged hybridisation step.||SNP array analysis of DNA, extracted from a cell population, cannot indicate the mosaicism within the sample.||NGS detects partial chromosomal gains and losses more precisely. NGS detects Aneuploidy and segmental imbalances at the same time.|
|Screening all 24 chromosomes at once requires a special probes set, requiring separate software at higher cost per sample.||Levels of mosaicism of 20% or less will not be detected.||Longer time needed to complete intended test.||NGS provides more accurate detection of mosaicism of the Trophectoderm cells from blastocyst biopsy.|
|Difficult to resolve chromosomal overlaps/split signals.||Relatively expensive.||Relatively expensive.||NGS offers reduced costs and enhanced precision. It allows parallel analysis for multiple embryos for a single patient. In a single run, samples from different patients can be analysed together as well.|
Claria PGS workflow
What is Preimplantation Genetic Diagnosis (PGD) ?
PGD is a diagnostic procedure to test the material collected from an embryo for the presence of specific mutations carried by one or both parents. This is carried out when one or both genetic parents has a known genetic abnormality. In PGD every test is prepared on a case-by-case basis.
What can Claria PGD detect?
- X linked disorders
- Single gene disorders
Who is Claria PGD for?
- Carriers of X-linked genetic disorders
- Carriers of single gene disorders
- Couples who have a child/ children affected by a single gene disorder
- Couples who have a family history of a single gene disorder
What are the benefits of PGD?
- PGD can test for most single gene disorders
- PGD allows the clinician to select embryos that do not carry the single gene disorder being tested for the implantation
- By using PGD, the single gene disorder can be prevented from being passed on from one generation to the next
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