Preimplantation Genetic Testing
What is PGT?
Preimplantation Genetic Testing is the process of genetic testing of embryos and transferring only healthy ones to the mother during IVF application.
Benefits of PGT
1- Increases the chance of success of IVF application.
2- Increases the clinical pregnancy rate.
3- Reduces the risk of pregnancy resulting in miscarriage.
4- Reduces the need for medical termination of pregnancy.
5- Reduces the multiple pregnancy rate.
6- Reduces the financial burden and psychological pressure caused by repeated unsuccessful IVF trials.
How is the PGT performed?
If you have a condition that requires a PGT, your doctor will recommend it.
Choosing healthy embryos requires a number of procedures:
Biopsy is applied to your embryos on the 3rd day (one or two cells are removed from each embryo) and this process does not harm your embryos.
Genetic test results for your embryos can be obtained within 6-12 hours. In special cases (such as rehibridization or application of molecular test methods) this period may be longer.
Embryos determined to be healthy are reported to be transferred to the expectant mother.
The transfer of embryos that are healthy and do not carry any diseases leads the mother into a healthy pregnancy.
Embryo Biopsy and PGT Reliability
To make preimplantation genetic diagnosis it is necessary to take cell samples from each of the patient's embryos. The probability of damage to embryos during the PGT application is negligibly low (the damage rate was determined as 0.3%). Although it varies according to the method used the probability of PGT test is estimated to vary between 2-7%. Reliability is higher in trophectoderm biopsies.
To who PGT should be applied?
1.Expectant mothers over 36 years old
- For couples who could not achieve pregnancy despite two or more IVF applications
- Couples with recurrent early pregnancy losses (miscarriages) (for reasons other than translocation carrier)
- Couples with balanced translocation carrier
5.Spouses who are at risk of single gene disorders that can be diagnosed such as Familial Mediterranean Anemia, Sickle Cell Anemia, Cystic Fibrosis, and SMA.
6.Selecting the HLA compatible embryo with family members
- Couples who have a child with a genetic disease from previous pregnancies
- Mothers with aneuploidy (chromosomal abnormality) pregnancy history
9.Gonadal mosaicism (despite two or more births with the same abnormality, the genetic test results of the spouses are normal)
10.TESE cases (cases with severe male infertility)
- Poor responders (cases with insufficient response to hyperstimulation protocol)
- Determination of embryonal sex in terms of diseases that are inherited by X chromosome, if direct genetic diagnosis of the disease in question cannot be made.
PGT in Single Gene Disorders
Single gene disorders are genetic diseases caused by the disruption of the functions of the units that we call "gene" encoded on our DNA. It is well known that such genetic diseases increase when spouses are related.
It is very important to diagnose such diseases in the prenatal period (prenatal diagnosis) and even in the embryo stage (preimplantation diagnosis) due to the high frequency of consanguineous marriages in our country. It is also possible to make preimplantation period diagnoses of all single gene disorders that can be diagnosed as postnatal (postpartum) or prenatal.
Preimplantation genetic diagnosis of single gene disorders is based on DNA analysis of single cell. Cystic fibrosis, Alpha L-1 antitrypsin failure, Retinitis pigmentosa, Hemophilia A1 and B, Talassemias, Alport, Gaucher's, Tay Sach's and Sickle cell anemia, Long chain acyl-CoA dehydrogenase deficiency, Multiple epiphyseal dysplasia, Achondroplasia, Neurofibromatosis, Eploidolysis, Eplondroplasia Preimplantation genetic diagnoses of a long list of diseases such as Myotonic dystrophy, X-linked hydrocephalus, Cancer predisposition and Fanconi anemia were made.
Our unit is able to provide “Preimplantation Genetic Diagnosis” service to spouses who are at risk of such genetic diseases, during which healthy baby embryos are selected during IVF applications. Among such diseases; Familial Mediterranean Anemia (Thalassemia major), HLA tissue compatibility tests, In addition to high frequency diseases such as Sickle Cell Anemia, Spinal Muscular Atrophy (SMA), Congenital Deafness, all diseases with a mutation have been identified.