Preimplantation Genetic Diagnosis
Currently, molecular biologists, geneticists and embriologists developed methods to analyze the embryo’s karyotype and genome before the implantation in the uterus: preimplantation genetic diagnosis (PGD). Conducting PGD is necessary in those cases when couples have a high risk of bearing a child with hereditary genetic disorders, so sometimes IVF with PGD and embryo selection is the only opportunity for couples at high risk of hereditary diseases to have a guaranteed genetically healthy offspring.
The method’s essence is that at the stage of 6-8 cells on the 2-3d days of embryo development, the high-precision laser knocks one embryo’s cell — blastomere whose genetic material is studied by geneticists and molecular biologists. The embryo that had blastomere biopsy performed continues to deve
lop as usual until geneticists finish their work. At the present stage PGD allows aged couples, couples with a high risk of hereditary diseases, couples with multiple IVF failures, couples with multiple pregnancy losses due to fetal chromosomal abnormalities to get successful pregnancy by IVF.
The violation of the chromosomes structure or its abnormal amount of the embryo is one of the most common causes for a common miscarriage — up to 50% of all early abortions. PGA and application of fluorescent hybridization method, FISH, allows for performing the selection of embryos that do not have such structural or quantitative deviations (analysis of chromosomes X, Y, 13, 15, 16, 17, 18, 21, 22) and achieving the normal development of pregnancy. Diagnostics of the whole karyotype is possible.