|Preimplantation Genetic Diagnosis (PGD – PGS)|
The effort to select healthy embryos is essential in the case of couples facing the danger of infecting their children with hereditary diseases; the painful requirement to terminate pregnancy is thus avoided. In 1990 the Hammersmith team gave birth to the first children (female twins) who had undergone biopsy as embryos in order to have their sex identified and thus avoid their infection with a sex-linked disease. The prevailing technique now involves 4 - 8 cell embryo biopsy because it offers the highest pregnancy rates compared to other techniques. Blastocyst biopsy unfortunately ensures low pregnancy rates, even though it enables the study of sufficient material. Embryo biopsy at the 8-cell stage removing one or two blastomers does not appear to harm embyo development, or impair implantation rates.
Currently, preimplantation genetic diagnosis has advanced. In addition to identifying embryo sex to prevent sex-related diseases, it enables diagnosing embryos carrying autosomal diseases, transferred in the recessive or the dominant way. In this country, the importance of preimplantation genetic diagnosis on beta thalassemia carriers is quite obvious. In addition to diagnosis, however, a gene therapy involving the insertion of normal DNA into the egg has also been proposed and is already being applied to guinea-pigs.
Nowadays the clinical application of preimplantation diagnosis has been established and is part of the other assisted reproduction techniques. In ‘BioDimiourgia’ we apply the FISH method and recently introduced the Array CGH technique, which enable us to examine all 46 embryo chromosomes in a signle test.
In the future it may also be used as a routine IVF method assisting the selection of healty embryos that can develop normally.