Genetic screening before second-generation embryo transfer (PGT-A 2.0)

Posted by Dr. Do Huy Duong - Medical Genetics Division, Vinmec High-Tech Center

Pre-implantation genetic testing for aneuploidy (PGT-A) is a genetic test performed on one or a few cells of an embryo to identify genetic abnormalities at the chromosomal level then select the best embryo before embryo transfer.

1. Genetic screening before second-generation embryo transfer

To this day, various techniques have been used to screen preimplantation embryos. Since the 1990s, the first version of PGT-A has been based on in situ hybridization (FISH) performed on day 3 embryos. However, several randomized clinical trials have shown that this technique does not clearly work. Increases fertility in IVF patients and in some cases reduces fertility.
In the past decade or so, a new generation of genetic screening tests for pre-embryo transfer has been introduced and widely developed (PGT-A 2.0). Different from the old generation (PGT-A 1.0), the new generation test (PGT-A 2.0) uses embryo biopsy samples on day 5 and evaluates the level of genetic abnormalities on all 23 chromosome pairs of embryos. compared with only a limited number of chromosome pairs examined using the FISH technique.

xét nghiệm sàng lọc di truyền trước chuyển phôi — Xét nghiệm sàng lọc di truyền trước chuyển phôi PGT-A 2.0 được đánh giá có nhiều ưu điểm vượt trội hơn so với PGT-A 1.0

2. PGT-A is the best tool for genetic screening in embryos

Recent research data shows that PGT-A 2.0 is more and more widely used and has gradually replaced the old generation of tests. The techniques that can be applied in PGT-A 2.0 include: single nucleotide polymorphism array (SNP array), comparative genomic hybrid array (aCGH) and the latest is substitution gene sequencing. new system (NGS). Research data on the PGT-A 2.0 generation all show positive results in improving the implantation rate, improving the pregnancy rate, reducing the rate of multiple pregnancies and improving the rate of healthy childbirth in IVF patients.
PGT-A 2.0 also showed a stable, high reproducibility of the test in different IVF centers.

3. PGT-A 2.0 improves the ability to select the right embryos for transfer and thereby improves implantation and pregnancy rates in IVF patients

Chromosomal aneuploidy is the main cause of an unsuccessful IVF cycle and this abnormality is proportional to maternal age. Selection of embryos with aneuploidy abnormalities rarely results in successful IVF. Many studies have shown that PGT-A 2.0 performed on day 5 embryo biopsies (trophoplasty cells) and identified abnormalities for all 23 chromosome pairs, providing accurate results for genetic status. of the embryo and makes the selection of transfer embryos more accurate and easier.
In addition, embryo screening with PGT-A 2.0 helps to assess potential for normal embryos in future IVF cycles.

Giai đoạn phôi nang (Ngày 5+) — PGT-A 2.0 nâng cao khả năng chọn đúng phôi chuyển

4. PGT-A 2.0 reduces miscarriage rate

Many embryos with aneuploidy abnormalities are still able to develop during implantation and thus assessment of total chromosomal abnormalities in the embryo will reduce the miscarriage rate associated with embryo transfer divergent.

5. PGT-A 2.0 increases the chances of a successful single embryo transfer IVF cycle

With PGT-A 2.0, a day 5 embryo with no abnormalities is selected for transfer. Thus increasing the probability of success of IVF single-embryo transfer. Moreover, in women around 42 years of age, PGT-A 2.0 improves preterm birth, reduces the proportion of children in intensive care after birth
Currently, genetic screening services before embryo transfer are performed at Vinmec International General Hospital.

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References:
Bellver J, Bosch E, Espinós JJ, Fabregues F, Fontes J, García-Velasco J, et al. Second-generation preimplantation genetic testing for aneuploidy in assisted reproduction: a SWOT analysis. Reprod Biomed Online. 2019;39:905–15

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Bài viết này được viết cho người đọc tại Sài Gòn, Hà Nội, Hồ Chí Minh, Phú Quốc, Nha Trang, Hạ Long, Hải Phòng, Đà Nẵng.