What is Preimplantation Genetic Testing for Aneuploidy (PGT-A)?
PGT-A is designed to identify which embryos have the correct number of chromosomes and thus have the greatest potential for a successful pregnancy.
Embryos with the normal number of chromosomes are called euploid embryos. Euploid embryos have 46 chromosomes and are created when a sperm with 23 chromosomes fertilizes an egg with 23 chromosomes. Sometimes embryos do not have the correct number of chromosomes (aneuploidy). Studies by the FEC and its collaborators have shown that transfer of embryos diagnosed as having aneuploidy failed to deliver healthy babies.
Aneuploidy is a common cause of miscarriage and can be associated with problems in a developing pregnancy. The prevalence of aneuploidy increases with maternal age. One of the most common examples of aneuploidy is trisomy 21, also referred to as Down syndrome, which is caused by the presence of a third copy of chromosome 21.
What is PGTseq-A?
Aneuploidy screening through the Foundation for Embryonic Competence (FEC) utilizes targeted next-generation sequencing (tNGS). PGTseq-A has been developed following extensive analytical and clinical validation studies and identifies whole chromosome aneuploidy (extra or missing whole chromosomes). PGTseq-A is greater than 98% accurate in screening for whole chromosome aneuploidy.
What is mosaicism and segmental aneuploidy?
Mosaicism refers to a combination of potentially chromosomally normal and chromosomally abnormal cells in a single embryo biopsy sample. Some studies suggest a mosaic result is associated with an increased risk for implantation failure and miscarriage. However, there is no consensus, and these studies are not conclusive.
Segmental aneuploidy refers to extra or missing genetic material from a part of a chromosome rather than from the whole chromosome.
Since the significance of these findings is uncertain, the FEC refers to them as secondary findings of uncertain clinical significance. You and your provider have the option to decide whether you would like the FEC to report secondary findings.