Preimplantation Genetic Testing: ACOG Committee Opinion, Number 799.

Preimplantation genetic testing comprises a group of genetic assays used to evaluate embryos before transfer to the uterus. Preimplantation genetic testing-monogenic is targeted to single gene disorders, and preimplantation genetic testing-aneuploidy is a broader test that screens for aneuploidy in all chromosomes, including the 22 pairs of autosomes and the sex chromosomes X and Y. To test embryos that are at risk for chromosome gains and losses related to parental structural chromosomal abnormalities (eg, translocations, inversions, deletions, and insertions), preimplantation genetic testing-structural rearrangements is used. Independent of the preimplantation genetic testing modality employed, false-positive and false-negative results are possible. Patients and health care providers should be aware that a "normal" or negative preimplantation genetic test result is not a guarantee of a newborn without genetic abnormalities. Traditional diagnostic testing or screening for aneuploidy should be offered to all patients who have had preimplantation genetic testing-aneuploidy, in accordance with recommendations for all pregnant patients. It is especially important to offer diagnostic testing or screening for aneuploidy after preimplantation genetic testing-monogenic or preimplantation genetic testing-structural rearrangements if concurrent preimplantation genetic testing-aneuploidy is not performed. Many limitations exist to preimplantation genetic testing and include challenges in detecting microdeletions and microduplications, de novo variants, and imprinting disorders. An emerging problem has been detection of mosaicism during preimplantation genetic testing-aneuploidy. The clinical utility of preimplantation genetic testing-monogenic and preimplantation genetic testing-structural rearrangements is firmly established; however, the best use of preimplantation genetic testing-aneuploidy remains to be determined. Future research is necessary to establish the overall clinical utility for preimplantation genetic testing-aneuploidy, the subset of patients that may benefit from preimplantation genetic testing-aneuploidy, the clinical significance of mosaicism, and residual risk for aneuploidy in preimplantation genetic testing-aneuploidy screened embryos.