Pre-Implantation-Diagnostics (PID) or Pre-Implantation-Genetic-Diagnosis (PGD) as it is known in Anglo-American countries has originally been developed as an alternative to prenatal diagnosis. Prenatal diagnosis involves performing amniocentesis or chorionic biopsy.
Pre-implantation-diagnostic testing allows the identification of possible chromosomal and genetic defects thus preventing affected egg cells from being transferred to the uterus.
Using the so called blastomere-biopsy (8-cell stage), diseased cells may be identified thus preventing affected embryos to be transferred to the uterus.
This is relevant, since 70 % of all miscarriages are linked to genetic disorders.
Prenatal diagnosis is only possible when a pregnancy is already established, whereas PID/PGD can be performed on the embryo before pregnancy occurs.
The PID technique involves investigating the genetic material of a single cell for possible defects. This can either be done by using the Polymerase Chain Reaction (PCR) or the Fluorescence In Situ Hybridisation (FISH) method.