Preimplantation genetic testing

Preimplantation genetic testing analyzes embryos created through in vitro fertilization for genetic or chromosomal characteristics before an embryo is transferred to the uterus.

In vitro fertilization: A process in which eggs are fertilized with sperm outside the body and resulting embryos may be transferred to the uterus. It creates the embryos that are sampled before transfer.
Preimplantation genetic testing for aneuploidy: Embryo testing that screens for abnormal numbers of chromosomes. It addresses chromosome-number differences rather than a specific inherited gene variant.
Cystic fibrosis: An inherited disorder caused by pathogenic variants in both copies of the CFTR gene. Embryos can be tested when both genetic parents carry relevant CFTR variants.
False positive: A test result that incorrectly indicates a condition or finding is present. A false-positive embryo result may wrongly exclude an embryo from transfer.
Embryonic mosaicism: The presence of genetically distinct cell populations within an embryo. It complicates predictions from a small biopsy about the embryo as a whole.
Embryo biopsy: The removal of cells from an embryo for laboratory analysis, commonly at the blastocyst stage. It supplies the cells used for genetic testing while the embryo remains outside the body.
Preimplantation genetic testing for monogenic disorders: Embryo testing for a specific genetic disorder caused by a variant in one gene. It targets a known familial variant associated with a single-gene condition.
Huntington's disease: An inherited neurodegenerative disorder caused by a pathogenic expansion in the HTT gene. Testing may help people at risk avoid transmitting the disease-causing variant.
False negative: A test result that incorrectly indicates a condition or finding is absent. A false-negative result can leave an affected embryo undetected.
Polygenic embryo screening: The use of many genetic variants to estimate an embryo's predisposition to complex traits or diseases. It extends selection beyond clear single-gene disorders, with uncertain predictive value.

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