It is about pre-implantation genetic screening of embryo for chromosomal aneuploidy and single gene mutations.

1. Pre-Implantation Genetic
Diagnosis (PGD)

2. Pre-Implantation

3. Concordance
• Forty-nine of 51 (96.1%) ICM samples were concordant with TE biopsies derived from the
same embryos. Discordance between TE and ICM occurred only in the two embryos with
structural chromosome aberration. Author concluded that TE karyotype is an excellent
predictor of ICM karyotype. Discordance between TE and ICM occurred only in embryos with
structural chromosome aberrations. (Johnson et al.)

4. PGD=?......
PGS=?........
PGT=?..........
PGT-M=?........
PGT-SR=?..........
PGT-A=?.................

5. Applications
• PGT-M (Pre-Implantation Genetic Testing for Monogeneic Disorders)
• To test specific genetic pathogenic variant (mutation) associated with a known diagnosis or known
predisposition within a family. It dose not test all single gene disorders at once and will not detect de
novo pathogenic variants.
• Single-gene disorders (eg, Huntington disease, cystic fibrosis, fragile X syndrome), including those that
are autosomal dominant and recessive or X-linked.
• Hereditary cancer syndromes (eg, hereditary breast and ovarian cancer, Lynch syndrome).
• To identify human leukocyte antigen-compatible, unaffected embryos gestated with the goal of allowing
ill family members to receive compatible bone marrow transplants or cord blood transfusions.
• Misdiagnosis is possible but rare with modern techniques.
• Confirmation of PGT-M results with CVS or amniocentesis should be offered.

6. • PGT-SR(Pre-Implantation Genetic Testing for Structural rearrangements)
• To test embryos that are at risk for chromosome gains and losses related to parental structural
chromosomal abnormalities (eg translocations, inversions, deletions, and insertions).
• Results confirmation with CVS or amniocentesis should be offered.

7. • PGT-A(Pre-Implantation Genetic Testing for Aneuploidy)
• To screen embryos for whole chromosome abnormalities.
• PGT-A helps to shorten the time to a viable pregnancy by reducing the need of multiple IVF cycles. Euploid
embryo transfer results in highest pregnancy rates and live birth rates reducing miscarriage risk
independent of maternal age.
• Sometime it may used for detect mosaicism, As embryos with mosaicism detected on PGT-A have not
been used for transfer in IVF because it is assumed they will not develop into euploid fetuses at term.`
• Next generation sequencing, has allowed mosaicism to be detected with greater sensitivity, with an
incidence as high as 20% of tested embryos.
• Prenatal diagnosis with CVS or amniocentesis should be strongly encouraged.

8. Screening OR Confirm Diagnosis
• Because of possible mosaicism, preimplantation genetic testing results from
the trophectoderm may not reflect the genetic constitution of the inner cell
mass . False-positive and false-negative results are possible.
• Confirmation of PGT results with chorionic villus sampling (CVS) or
amniocentesis should be offered.

9. INDICATIONS
• Repeated implantation failures.
• Repeated pregnancy loss.
• Advanced maternal and paternal age.
• Male factor infertility.
• Genetic disorders in the parents including mosaicism of sex chromosomes,
structural rearrangements, and monogenic genetic diseases.

10. Available Technology
• FISH (fluorescent in situ hybridization)
• CGH (Comparative Genomic Hybridization)
• QT-PCR (Quantitative Real-Time PCR)
• Microarray
• NGS (next-generation sequencing)

11. Kits
• Whole Genome Amplification: Detects aneuploidy and >48Mbp chromosomal arm
events.
• Low-pass genome sequencing methods are not intended to detect polyploidies.
• Mosicism detection: whole-chromosome mosaicism of ≥20%
• Repro-Seq
– Bundle Solution (Library prep + Chip + Chef and Sequencing consumables)
– Available in three different sizes [510 (64 Rxn), 520 (96 Rxn) & 530 (384 Rxn)]
• Single-Seq
– Only Library preparation kit will be suplied , For sequencing, pooling with other available
compatible test can be done.
– Available in two different pack sizes (24 Rxn & 96 Rxn)

12. Baseline & Validation
• Baseline creation
• Thermo scientific application specialist will help in creation of baseline.
• We need to provide extracted DNA of 15 male samples whose Karyotyping is
known and must be NORMAL.
• Validation
• Discussion is going- on, we will be required some embryo biopsy for
validation.

13. Reference
• Parikh FR, Athalye AS, Naik NJ, Naik DJ, Sanap RR, Madon PF. Preimplantation Genetic
Testing: Its Evolution, Where Are We Today? J Hum Reprod Sci. 2018 Oct-Dec;11(4):306-314.
doi: 10.4103/jhrs.JHRS_132_18. PMID: 30787513; PMCID: PMC6333033.
• D.S. Johnson, C. Cinnioglu, R. Ross, A. Filby, G. Gemelos, M. Hill, A. Ryan, D. Smotrich, M.
Rabinowitz, M.J. Murray, Comprehensive analysis of karyotypic mosaicism between
trophectoderm and inner cell mass, Molecular Human Reproduction, Volume 16, Issue 12,
December 2010, Pages 944–949, https://doi.org/10.1093/molehr/gaq062
• Preimplantation genetic testing. ACOG Committee Opinion No. 799. American College of
Obstetricians and Gynecologists. Obstet Gynecol 2020;135:e133–7.
(https://www.acog.org/clinical/clinical-guidance/committee
opinion/articles/2020/03/preimplantation-genetic-testing)

14. Take Home Message
• PGT- A is a useful in best embryo selection procedure for transfer from multiple options
available. It helps to higher success rate and lower IVF cycles.
• But need to understand that it is a screening test and it does not confirm or promise the
healthy baby. Further confirmatory test should be offered from CVS or amniotic fluid.
THANK YOU