What are the indications for preimplantation genetic testing (PGT)?

• A. Known genetic disorders, high aneuploidy risk, or chromosomal rearrangements
• B. Universal use for all IVF cycles
• C. Guarantees a healthy baby
• D. Replaces genetic counseling

Answer: (A)

Indications for preimplantation genetic testing focus on preventing transmission of known genetic risks to the embryo. It is most appropriate when there is a known genetic problem that could be passed on to a child, or when the likelihood of abnormal chromosome numbers is higher and could lead to miscarriage or a affected baby. Specifically, this includes scenarios where one or both parents carry a known single-gene disorder, situations with a high risk of aneuploidy (such as advanced maternal age or a history of miscarriages due to chromosomal abnormalities), and when a parent has a chromosomal rearrangement like a balanced translocation that could produce affected embryos.

Breaking it down, PGT is done in conjunction with IVF to test embryos for these issues before transfer. PGT has different forms: PGT for single-gene disorders, PGT for aneuploidy, and PGT for structural rearrangements. The goal is to select embryos that are free of the specific genetic problem or chromosomal abnormality, reducing the chance of affected offspring and pregnancy loss.

However, PGT does not guarantee a healthy baby. Mosaicism can complicate results, tests have limitations based on what and how they screen, and not all conditions are detectable with current testing. It’s also not used universally for every IVF cycle; the decision depends on the individual risk profile. Genetic counseling remains essential to interpret test results, discuss options, and guide family planning decisions.