This technique consists in the genetic analysis of embryos at the start of their in-vitro development with a final view to transferring the ones diagnosed as healthy.
PGD is necessarily linked to assisted reproduction techniques. Couples must undergo an in-vitro fertilisation cycle, because the ovary stimulation and puncture must enable a sufficient number of oocytes to be obtained and subsequently embryos, which guarantees the transfer of at least one normal embryo for the genetic diagnosis studied. The embryo biopsy for the genetic analysis must be carried out on the third day of its development or in the blastocyst stage. The embryos that are free of the alternation searched for, if they have developed well in-vitro, can be transferred to the maternal uterus to achieve gestation and the birth of a baby without genetic diseases. The affected embryos are discarded.