About PGT-A and PGT-M

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ADVERTORIAL

What is PGT-A?

PGT-A stands for Pre-implantation Genetic Testing for Aneuploidy. As its name suggests, it is a genetic test performed on your embryos before their implantation. This test allows for the screening of aneuploidies or an abnormal number of chromosomes, which may cause implantation failure and miscarriage. Aneuploidy may also lead to various chromosomal disorders such as Down’s syndrome and Turner syndrome.

How is the test performed?

Routine IVF cycle is performed and the subsequent embryos are cultured to the blastocyst stage (Day 5 and 6), at which point several cells are biopsied from the blastocyst. These cells are sent for genetic testing while the blastocyst is cryopreserved for later use.

Embryo development.

Is biopsy harmful to my blastocyst?

When the biopsy process is carried out on the blastocyst which has roughly 100-200 cells, the risk to the blastocyst is minimal, as only a few cells are removed during the process (normally 3-6 cells). In the past, biopsies were performed on Day 3 embryos, which would typically have 8 cells. As expected, the success rates then were lower, as by removing even one cell from the 8-cell embryo would entail a 12.5 per cent loss of the embryo’s cell number, compared with 4 per cent at the blastocyst stage. An additional advantage of blastocyst biopsy is the additional genetic material for testing (3-6 cells vs 1 cell), which would entail a more accurate genetic result for the embryo. As such, a majority of IVF centres have moved towards blastocyst biopsies for PGT-A testing, where the risk of harming the embryo is minimal.

Is PGT-A for me?

The percentage of abnormal embryos increases with maternal age, and to a lesser degree, paternal age. This is especially true for women above 35, in which the rate of attaining abnormal embryos increases dramatically. Furthermore, PGT-A will benefit couples who have had recurrent miscarriages or implantation failure. As aneuploid blastocysts that will cause adverse outcomes in pregnancies are deselected, even if you do not fall in the above groups, PGT-A will allow you to have a higher chance at a pregnancy and a shorter time-to-pregnancy.

Increased percentage of abnormal embryos as maternal age increases.

The percentage of abnormal embryos increases with maternal age. This explains why the chance of a pregnancy for older patients is lower. However, once we identify the normal embryo, the chance of pregnancy will be the same as in younger patient.

What are the benefits of PGT-A?

⦁ Higher implantation rate
⦁ Reduce the risk of adverse outcome in pregnancies
⦁ Single embryo transfer – Reduce complications associated with multiple pregnancies
⦁ Decrease time to pregnancy
⦁ Increase cost-effectiveness

Who will benefit from PGT-A?

⦁ Advanced Maternal Age
⦁ Recurrent Implantation Failure
⦁ Recurrent Miscarriage
⦁ Severe male factor (oligoasthenoteratozoospermia, OATS)
⦁ Previous history of child with aneuploidy
⦁ Routine Screening

PGT-M

Pre-implantation Genetic Testing for Monogenic Disorder

What is PGT-M?

PGT-M stands for Pre-implantation Genetic Testing for Monogenic Disorder. Similarly to PGT-A, it is a genetic test performed prior to implantation. However this test is a targeted screening of single gene inherited diseases for both rare and more common diseases such as thalassemia, muscular dystrophy, ATRX syndrome and etc… With this, the chance of passing on specific single gene disorder can be reduced or prevented.

What’s more, PGT-M can be performed along with Human Leucocyte Antigen (HLA) typing in order to identify embryo that are HLA-compatible a child who needs of bone marrow or cord blood transplant.

How is the test performed?

PGT-M requires a preparation test prior to IVF cycle. Genetic counselling with our in-house genetic counsellor will be carried out and family histories will be accessed. DNA samples from the couple and their family member(s) will be collected (blood/saliva) then tested in advance. Once the preparation is ready, similar to PGT-A, routine IVF is then performed and the subsequent embryos are cultured to the blastocyst stage (Day 5 & 6), at which point several cells are biopsied from the blastocyst. These cells are sent for genetic screening while the blastocyst is cryopreserved for later use.

What are the benefits of PGT-M?

⦁ Reduce the risk of passing on affected gene(s) to next generation
⦁ Decrease time to pregnancy
⦁ Increase cost-effectiveness
⦁ Assist in the search of a HLA-compatible donor embryo to the affected child

Who will benefit from PGT-M?

⦁ History of pregnancy termination(s) due to a serious genetic disorder
⦁ Couple have child with genetic disorder
⦁ Couple who wants to perform HLA matching
⦁ Couples who have a family history of any inherited genetic condition
⦁ Couple with inherited mutated gene(s) (pre-marital screening / carrier screening test)

How does PGT-M different from PGT-A?

PGT-M:

Screening of known single gene inherited disease (Eg: Thalassemia, cystic fibrosis, Marfan syndrome, muscular dystrophy, beast cancer, etc).

PGT-A:

Screening of aneuploidies or an abnormal number of chromosomes (Eg: Down syndrome, Turner syndrome, Edward syndrome).

Source: Dr Aaron Chen Jang Jih, Lead Preimplantation Genetic Testing Scientist. Sunfert International Fertility Centre

KKLIU 0784/EXP 31.12.2025