How can preimplantation genetic diagnosis identify genetic abnormalities in embryos?

Preimplantation genetic diagnosis (PGD) identifies genetic abnormalities in embryos created via in vitro fertilization by analyzing cells extracted from the embryo prior to implantation in the uterus.21

The process typically involves a biopsy where one or two cells are removed from an embryo, usually three days after fertilization. These cells undergo specific genetic analyses depending on the suspected condition:21

• Polymerase chain reaction (PCR): Used to detect single-gene mutations, such as those causing cystic fibrosis or Tay-Sachs disease.21
• Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH): Used to identify chromosomal defects, including aneuploidy (abnormal chromosome number) and structural abnormalities like translocations.21

While PGD is a valuable tool for preventing the transmission of inherited diseases, it is ethically complex. It is essential to recognize that the procedure carries risks of false positives and false negatives, and its application raises significant moral questions regarding disability, sex selection, and equitable access to reproductive technologies.2