Tarih:Feb 06, 2017 Yazar:Ender Yalcinkaya Kalyan
Preimplantation genetic diagnosis is the evaluation of genetic material of the embryos before transfer during in vitro fertilization treatment. This technique has been used extensively in the world and in our country. With the advances in technology, more number of chromosomes can be examined today. Previous reports showed that almost 50% of the embryos which were grown up even to the blastocyst stage during in vitro fertilization treatment had defects in their genetic structure. This phenomenon can explain the failures with good quality embryos or early abortions in case of non-endometrial indications.
Of course, it is important to apply this technique to the right patient group in case of specific indications. The indications of preimplantation genetic diagnosis are as follows:
-the presence of a genetically transmitted disease within the family.
-the presence of a child with a genetic disease in the family.
-the presence of 2-3 failed IVF attemps
-the presence of repeated implantation failures.
Preimplantation genetic diagnosis is highly recommended for the patients who apply to the abovementioned indications. Today, genetic tests that scans all chromosomes are recommended mostly. For the patients especially who experienced numerous failed IVF attempts, tests like cgh array and NGS (next generation sequencing) which show numerical aberrations (aneuploidies) in all sets of chromosomes introduce more detailed and significant data. For the implementation of these tests, patients should start IVF treatment at first and her embryos should reach up to a specific cell numbers. Cells are taken from the embryos at cleavage or blastocyst stage depending on the patients' situation by biopsy method and they are sent for genetic testing. If biopsy is performed at day 3, fresh embryo transfer may be done at day 5 since the results can come back in two days. However, especially for cases with higher number of embryos, trophoectoderm biopsy is better to plan. Since the results come after 48 hours, biopsied blastocysts are frozen at day 5; and then the embryos with normal chromosomes can be thawed and transferred later (you can see the video regarding trophoectoderm biopsy in the video gallery).
We share the genetic results of the embryos with the patients after getting all necessary information from the geneticist. We transfer the genetically-healthy embryos after having genetic consultation. However, it is also recommended to confirm these results with detailed prenatal tests after getting pregnant.
Since preimplantation genetic diagnosis procedure helps us to discriminate genetically healthy and abnormal embryos, it makes a nearly 10% contribution to pregnancy results.However; I again want to emphasize that it is a diagnostic test. It simply helps to detect genetically abnormal embryos, not to correct chromosomal aberrations.
You can contact with me if you have further questions about the topic. Take care.