Preimplantation genetic diagnosis: The earliest form of prenatal diagnosis

Preimplantation genetic diagnosis (PGD) can provide genetic information on embryos obtained through in vitro fertilization (IVF), allowing implantation of embryos identified as unaffected with a given genetic or chromosomal disorder. With the availability of increasingly sophisticated genetic testing, its use has advanced from the selection of female embryos for the prevention of X-linked genetic diseases to testing for single gene disorders via PCR. Recently, PGD has also been used in the setting of assisted reproductive technology to select for chromosomally normal embryos in an effort to increase the rates of implantation and successful pregnancy. As the number of patients undergoing IVF increases, the indications for its use broadens, and more mutations underlying genetic disorders are identified, PGD is becoming more widespread. As this evolution continues, recognition of the limitations of PGD, as well as ethical concerns regarding use and misuse of this technology, need to be considered by patients, clinicians, and policy makers.