What is Preimplantation Genetic Testing (PGT) and how can PGT help you?

Preimplantation Genetic Testing (PGT) is performed in conjunction with an In Vitro Fertilization (IVF) cycle to test parts of the embryos genetics and to select embryos with the highest likelihood of resulting in a healthy on-going pregnancy.

1. Types of PGT?
2. Why Do PGT Testing?
3. How is PGT Performed?
4. Preimplantation Genetic Testing for Aneuploidy (PGT-A)
5. Preimplantation Genetic Testing for Monogenic Single Gene Defects (PGT-M)
6. Preimplantation Genetic Testing for Human Leukocyte Antigen (HLA) Matching (PGT-M-HLA)
7. Preimplantation Genetic Testing for Structural Rearrangements (PGT-SR)

1. Types of PGT?

There are various types of PGT available, depending on the requirements of the individual couples,

• PGT-A (aneuploidy),
• PGT-M (monogenic single gene disorders),
• PGT-M (HLA) (a special subset of PGT-M for HLA Matching), and
• PGT-SR (structural re-arrangements of chromosomes).

2. Why Do PGT Testing?

Chromosomes are the blueprints of our body and are important for healthy development. They are the structures in our cells that carry our genetic information (genes).

Chromosomal aneuploidy (wrong number of chromosomes) is the most common cause of miscarriage and implantation failure. Preimplantation Genetic Testing (PGT) is the only way to determine if an embryo is expected to be affected with chromosomal aneuploidy or a genetic condition prior to implantation and achieving a pregnancy.

So what are some of the reasons for doing PGT Testing?

• Avoid embryos with chromosomal aneuploidy and thereby;
  • Improve Pregnancy Rates
  • Reduce Chances of Miscarriage
• Provide an embryo of specific genetics (eg. certain sex)
• Avoid embryos with a known familial genetic mutation and thereby avoid passing the familial disorder onto your children
• Provide families with a child who is HLA-matched to an existing affected sibling.

At Superior A.R.T., it is our aim to provide families with the best chance of having a healthy baby. A team of IVF clinicians, nurses, scientists and support staff work to support you and your family along the IVF and PGT journey.

3. How is PGT Performed?

PGT is performed in conjunction with an IVF cycle. Following oocyte (egg) retrieval and fertilization, the embryos are cultured to be blastocysts (day 5 to 6 embryo), and a few cells are removed (biopsied) from the outer layer (trophectoderm) and are transferred to the Genetics laboratory at Superior A.R.T. for analysis. Superior A.R.T. genetic scientists have experience and expertise in the most current, state-of-the-art PGT techniques, offering the most accurate and comprehensive results.

4. Preimplantation Genetic Testing for Aneuploidy (PGT-A)

PGT-A determines if an embryo contains the normal number of chromosomes (euploid) prior to implantation and pregnancy. Transfer of a euploid embryo optimizes the success of an IVF cycle, increasing pregnancy rates and reducing the chance of miscarriage.

The indications for PGT-A include,

• Advanced Maternal Age
• Testing Previously Frozen Embryos
• Repeated IVF Failures
• Recurrent Pregnancy Loss
• Require specific genetics or family balancing.

Superior A.R.T. offers testing for all 24 chromosomes, using Next-Generation Sequencing and state-of-the-art technologies with the capacity to test all the chromosomes.

5. Preimplantation Genetic Testing for Monogenic Single Gene Defects (PGT-M)

PGT-M tests for a specific known family genetic condition prior to implantation and pregnancy. These disorders can include autosomal dominant, autosomal recessive, and X-linked conditions. Doing PGT-M helps at-risk couples have a child free of their family’s genetic disorder. These single gene disorders are caused by an alteration (mutation) in a specific gene, and PGT-M is the only way to determine if an embryo is expected to be at risk of that genetic condition.

The indications for PGT-M include,

• Couples with an individual or a family history of a genetic condition and therefore at risk of passing it on to their children
• Families with a child affected by a disorder treatable by stem cell transplant. (see PGT-M (HLA))
• Couples Identified to be carriers with a risk of having children with a genetic disorder

Superior A.R.T. has for more than 15 years been a premier provider of PGT-M in Asia. Superior A.R.T. can customize and develop novel tests as necessary, have never failed to provide a test for any known family genetic disorder, and have developed tests for more than 250 disorders. We can also perform testing for more than one single gene disorder and/or a chromosomal rearrangement on the same sample. An individualized family testing plan (“PGT-M Work-Up”) is developed for each couple, requires DNA samples from each partner and may require additional DNA samples from some family members selected according to a review of the family history.

PGT-M uses Next-Generation Sequencing, PCR based fragment analysis, and other state-of-the-art technologies such as Karyomapping. The choice of testing will depend on individual families and their disorder(s). Normally, PGT results are known within 10-14 business days.

6. Preimplantation Genetic Testing for Human Leukocyte Antigen (HLA) Matching (PGT-M-HLA)

PGT-M (HLA) is the same as for PGT-M except than in addition to testing for a specific genetic disorder, the testing also identifies embryos that are HLA compatible with an existing child affected with certain blood disorders, treatable by stem cell transplant. Cord blood can be collected at birth and stem cells harvested. These Allogeneic haematopoietic stem cell (HSC) through transplantation represents the only curative option for leukemia and certain other genetic and non-genetic disorders (eg. thalassemia). The PGT-M (HLA) Work-Up includes creating a DNA fingerprint of the affected child’s HLA region, and then determining if the HLA region in an embryo is the same or different.

Superior A.R.T. is recognized as a successful leader in PGT-M for HLA-Matching in Asia.

7. Preimplantation Genetic Testing for Structural Rearrangements (PGT-SR)

PGT-SR identifies structural chromosomal abnormalities caused by rearrangements, including translocations, inversions, deletions and duplications, prior to implantation and pregnancy.

Since, as previously stated, chromosomes are the blueprints of our body, the structures in our cells that carry our genetic information (genes), any re-arrangement, loss (deletion) or gain (Insertion), may cause failed implantation, miscarriage, or a child born with a disorder.

Typically, the couple has a previously identified translocation, inversion, or other chromosomal rearrangement, and these tests identify any chromosomal abnormalities in an embryo, prior to achievement of a pregnancy.

PGT-SR for chromosomal rearrangements uses Next-Generation Sequencing and other state-of-the-art technologies. The method detects not only unbalanced embryos, but also identifies aneuploid embryos. For smaller fragments, the development of a special tests may be required.

Conclusion

Superior A.R.T. is a recognized leader in Asia in the field of assisted reproductive technologies and Preimplantation Genetic Testing (PGT), providing assistance and successful healthy pregnancies for thousands of couples and families.