During this webinar, Dr Ángela Llaneza, Fertility Specialist at Clinica Tambre shared an overview of PGT-A and discussed its indications such as advanced maternal age, recurrent pregnancy loss, etc. From this webinar, you will be able to learn how PGT-A can help optimize fertility treatment decisions and decrease the time for a successful pregnancy.
Definition and purpose of PGT
Preimplantation Genetic Testing (PGT) is a procedure that allows us to study the genetic composition of embryos before they are transferred into the uterus. The embryos are typically frozen during this process to enable sufficient time for diagnosis. PGT involves extracting cells from the trophoderm, which will become the placenta, leaving the embryo itself untouched and unharmed. This safe and reliable technique helps identify healthy embryos and detect genetic conditions, including monogenic diseases such as cystic fibrosis.
Indications and types of PGT
PGT serves two primary medical indications: confirming a normal karyotype in embryos and identifying disease-free carriers or non-carriers, thus ruling out potentially unhealthy embryos. Advanced maternal age is also a common reason for undergoing PGT, as older oocytes have a higher likelihood of chromosomal abnormalities. Depending on the type of results sought, there are three variations of PGT: PGT-A for chromosomal analysis, PGT-SR for balanced chromosome composition, and PGT-M for studying monogenic diseases.
Impact of Maternal Age on PGT Success
Maternal age plays a significant role in the success of PGT. As women age, the chances of producing healthy embryos decrease, leading to increased rates of aneuploidy (abnormal chromosome count) and higher miscarriage rates. By using PGT to identify chromosomally normal embryos, the chances of a successful pregnancy can be substantially increased. Recent research has shown that as long as the embryo is chromosomally normal, the pregnancy success rates remain consistent regardless of maternal age.
The PGT laboratory procedure involves extracting cells from the embryo’s trophoderm in a process known as biopsy. After the biopsy, the cells are sent to the genetics lab for extensive testing, typically using Next Generation Sequencing (NGS), which provides highly accurate results. The entire process takes around two to three weeks. While rapid results using another technique called array are possible, it is generally advisable to wait for NGS results due to its superior accuracy.
Understanding PGT Results
The PGT results can yield three possible diagnoses: euploid (chromosomally normal) embryos, aneuploid (chromosomally abnormal) embryos, and mosaic embryos containing both euploid and aneuploid cell lines. Euploid embryos can be transferred with confidence, while aneuploid embryos are not suitable for transfer to avoid potential health issues. Mosaic embryos require further genetic counseling and diagnostic assessment before deciding on transfer options.
In conclusion, Preimplantation Genetic Testing (PGT) is a valuable tool in modern assisted reproductive technology. It aids in identifying healthy embryos, detecting genetic conditions, and increasing the success rates of IVF procedures, especially for women of advanced maternal age. With thorough genetic testing and counseling, PGT offers new possibilities for creating healthy families.