What is Preimplantation genetic testing for aneuploidy: PGT-A
Every cell in an embryo should contain 23 pairs of chromosomes – 46 chromosomes in total, known as euploid. One chromosome from each pair comes from the sperm and one from the egg that creates the embryo. As the cells of the embryo divide the chromosomes are copied and each new cell contains an identical copy of the same 46 chromosomes.
Sometimes, the sperm or egg that form an embryo has fewer or more than 23 chromosomes and because of this, the resulting embryo also has too few or too many chromosomes, known as aneuploid. These embryos may fail to develop or develop in the laboratory but fail to implant or implant but lead to pregnancy loss. Sometimes, an embryo with more or fewer than 46 chromosomes can develop to term but the baby is affected by a serious condition like Down’s syndrome (where there are three copies of chromosome 21) or Turner’s syndrome (which occurs when girls inherit only one X chromosome and so have only 45 rather than 46 chromosomes).