ABSTRACT
Although preimplantation genetic diagnosis (PGD) was initially introduced for pre-existing genetic conditions, its application appears to be of particular relevance for sporadic conditions, such as chromosomal abnormalities, that contribute significantly to pregnancy loss and infertility. At least three-quarters of all PGDs have been performed for age-related aneuploidies, resulting in the birth of thousands of healthy children. PGD is currently performed by three main approaches-the testing of biopsied trophectoderm cells at the blastocyst stage (day 5), blastomeres biopsied from the cleaving embryos (day 3), or polar bodies removed from matured and fertilized oocytes (day 0)— combined with fluorescent in situ hybridization (FISH) or microarray analysis.
