Preimplantation Genetic Testing for Aneuploidy (PGT-A) is a procedure used to identify chromosome abnormalities in embryos. PGT-A involves screening all chromosomes from cells that have been extracted from an embryo prior to the embryo being transferred to the uterus. .
Each cell in our body should contain 46 chromosomes (22 pairs and the two sex chromosomes). The chromosomes are numbered from 1-22 and the sex chromosomes are called X and Y. A female will have two X chromosomes and a male will have one X and one Y chromosome.
An embryo is abnormal (aneuploid) when there is an incorrect number of chromosomes in the embryo. For example, Down’s syndrome disorder is caused by the presence of a third copy of chromosome 21.
Eggs and sperm contain 23 chromosomes each. When the egg and sperm join together at fertilisation the embryo should have 46 chromosomes in its cells, made up of 22 pairs of chromosomes numbered 1 - 22 and the sex chromosomes. Chromosomal abnormalities can originate in the egg, sperm, or embryo, although it is thought that the majority originate in the egg. It is known that the rate of chromosome abnormalities in the egg increases with advancing female age.
Embryos that develop to the blastocyst stage and are of suitable quality can be biopsied. The biopsy involves removing a small number of cells (the biopsy sample) from the outer layer of the embryo (the trophectoderm). The embryo is frozen after the biopsy and the biopsy sample is analysed.
Once the results from the biopsy sample are received, embryos with the correct number of chromosomes are thawed and transferred in a Frozen Embryo Transfer Cycle. Any additional normal embryos will remain frozen and stored for future use.
The Western Australian Reproductive Technology Act 1991 (amended 2004) allows the following patients to access PGT-A:
PGT-A should be discussed with your fertility specialist followed by a meeting with the Scientific Director.
If PGT-A testing is the right option for you, you can then commence an IVF cycle with ovarian stimulation before an egg collection procedure. Your embryos will be cultured in the laboratory and any embryos that are suitable will be biopsied and frozen.
The results of PGT-A testing are then available a few weeks after biopsy is completed
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