Preimplantation Genetic Screening in Older Mothers

Abstract

Preimplantation genetic diagnosis, first described in 1990,¹ involves removing one or two cells from an embryo for genetic testing in order to prevent transmission of genetic disorders from a parent who is known to carry a genetic abnormality. Genetic tests are done on the third day after in vitro fertilization (IVF), when the embryos are at the eight-cell stage of development; only embryos without specific genetic traits are transferred to the mother a day or two later. The procedures involved are polymerase chain reaction (PCR) for known single-gene defects or fluorescence in situ hybridization (FISH) to identify chromosomal abnormalities. Of . . .