PGS and PGD
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PGS(PGT-A)
Known as Preimplantation Genetic Testing for Aneuploidies (PGT-A), is a procedure that checks for the presence of an abnormal amount of chromosomes in each of your embryos before the embryo transfer in an IVF treatment. Abnormal chromosome numbers, also known as aneuploidy, refers to an embryo with more or less than 46 chromosomes. When an embryo has an abnormal amount of chromosomes, the possibility of no pregnancy, pregnancy loss, or significant health issues in the fetus may occur. The PGS/PGT-A procedure involves culturing the embryos until they’ve reached the blastocyst stage and then performing a biopsy to test a sample of cells from the embryo(s). If executed properly, PGS/PGT-A doesn’t damage the embryo so a successful IVF embryo transfer is possible after this procedure.
Who should receive the PGS?
- Women over the age of 35
- Those who have more than 2 miscarriages
- Those who experienced repeated IVF failures
- Those with a family history of chromosomal abnormalities or chromosomal translocation
- Male infertility syndrome
With PGS reprot, it can show:
- Chromosomes are not set in place: Down Syndrome, Turner’s Disease, Edward’s Disease, Patau Disease
- Large chromosome deletion (>10Mb): Prader-Willi Syndrome, Cri Du Chat Syndrome, DiGeorge Syndrome, Angelman Syndrome
Can PGS fail to screen out abnormal conditions?
- The embryo could be mosaic, and depending on the severity of the case it may be unable to develop normally after transfer
- The sample size is small (<10Mb)
- Cannot distinguish balanced and structurally normal embryos from translocation carriers
PGD(PGT-M)
- PGD, also known as Preimplantation Genetic Diagnosis (Preimplantation Genetic Testing for Monogenic/Single Disorders), is a reproductive technology used alongside an IVF cycle to increase the chances for a successful pregnancy and delivery. PGD is a genetic test on cells removed from embryos to help select the best embryos to achieve pregnancy or to avoid a genetic disease for which a couple is at risk.
Who should receive the PGD?
- Spouses and those with Hemophilia, Thalassemia, Ankylosing Spondylitis, Spinocerebellar Ataxia, etc.
PGD Limitations
Preimplantation genetic diagnosis can only test for 11 out of the 23 pairs of chromosomes. Abnormalities in the remaining 12 chromosomes cannot be detected. PGD cannot detect genetic mosaicism.
