The techniques of genetic diagnosis preimplantation analyze the chromosome complement of embryos obtained from a cycle of Medically Assisted Procreation (MAP) before their transfer to the uterus. Knowing the genetic makeup of the fetus allows to exclude genetic diseases and chromosome abnormalities. The techniques of preimplantation genetic diagnosis are able to analyze both the chromosome makeup of the embryo in its entirety (Preimplantation Genetic Screening, PGS) and the genetic disorders associated with individual genes or mutations affecting one or both parents (Preimplantation Genetics Diagnosis, PGD).

The analysis of the chromosome makeup for the research of a mutation of a single embryo gene allows the transfer of genetically normal embryos, avoiding the transmission of the genetic disease, of which one or both parents are carriers. Any disorder of which genetic causation (gene/mutation) is known can be analyzed by preimplantation genetic diagnosis.

The analysis of the chromosome makeup (PGS) of the embryo before the transfer allows to identify any numerical abnormalities in the chromosomes, allowing the transfer of the genetically normal embryos.
Most of these chromosome abnormalities are incompatible with the embryo implantation in utero and are responsible of recurrent abortion. The occurrence of such chromosome abnormalities during gametogenesis has no hereditary character: for this reason it can affect even embryos generated by genetically healthy parents