What is Preimplantasion Genetic Diagnosis (PGD) ?
Preimplantation Genetic Diagnosis is known as a test application where embryos formed in the laboratory before birth are inspected. Preimulation is performed by taking 1 or 2 cells from the embryos formed as a result of fertilization of sperm and egg cells. Numerical and structural chromosomal disorders and single gene diseases (such as thalassemia, sickle cell anemia, cystic fibrosis) are controlled in the baby who will be born with preimplantation control. As a result of these controls, healthy embryos can be easily transferred to the mother.
Why is Preimplantation Genetic Diagnosis Important?
Preimplantation genetic diagnosis is of great importance for the pregnancy period. The benefits obtained as a result of preimplantation genetic diagnosis are listed below:
• As a result of the preimplantation genetic diagnosis, the application of in vitro fertilization procedures is performed easily.
• Preimplantation procedure increases the rate of conception.
• As a result of preimplantation genetic diagnosis, the miscarriage rate of pregnant women is minimized.
• Preimlantation genetic diagnosis reduces any adverse conditions experienced during pregnancy.
• It minimizes the rate of multiple pregnancy.
Common Features of Preimplantation Genetic Diagnosers
Those who want to have preimplantation genetic diagnosis must have certain characteristics. Below are the features that should be found for those who want to have preimplantation procedure:
• For mothers aged 36 and over,
• Couples whose pregnancy could not be achieved despite two or more IVF applications,
• Couples with recurrent early pregnancy losses,
Balanced translocation carrier pairs,
• Spouses at risk in terms of some single gene diseases that can be diagnosed such as Familial Mediterranean Anemia, Sickle Cell Anemia, Cystic fibrosis, SMA,
• Couples who have a child with a genetic disease from previous pregnancies,
• Mothers with pregnancy history with aneuploidy,
• Gonadal mosaicism cases,
• TESE facts,
• In cases such as poor responders, preimplantation diagnosis can be made.
What are the health problems associated with a single gene?
In order for a single gene diagnosis to be made in embryo periods, it is necessary to go through a very difficult process. In order to make a single gene diagnosis, the DNA change must be known and diagnosed beforehand. In some cases, making a single gene becomes impossible. Below are the reasons why one gene cannot be made:
• The disease has not been diagnosed,
• Clinically diagnosed, genetic tests are not performed or not,
• A single gene diagnosis is not made in couples where DNA tests are found to be normal.
What Are Chromosome Related Diseases?
Chromosome related diseases are divided into two main groups as numerical and structural. These diseases are detailed below:
Numerical Chromosome Diseases: Klinefelter (46, XXY) and Mosaic Turner (46, XX / 45, X)
Structural Chromosome Diseases: Translocation and Inversion
Types of Diseases with Preimplantation Genetic Diagnosis
Certain diseases must be seen in order to make preimplantation diagnosis. Below are the types of diseases that occur in the preimplantation genetic diagnosis application:
Structural Chromosome Disorders: Reciprocal translation, Robersonian translation, Inversion, Microdeletion syndromes, X chromosome deletions
Numerical Chromosome Disorders: Klinefelter syndrome, Mosaic Turner syndrome, XXY, XXX, Marker chromosome
Single Gene Diseases: Leukemia- HLA, Hemophilia A- F8, Familial Mediterranean fever- MEFV, Wilson’s disease-ATP7B, Thalememia – HBB, Sickle cell anemia-HBB, Hemophilia B-F9, Pompe disease-GAA, Galactokinase-GALK1, Spinal Muscular atrophy-SMN, Duchenne- DMD, Fragile X-FMR1, Gaucher disease-GBA, Phenylketenuria- PAH, Neurofibromatosis- NF1, Citrullinemia type1- ASS1, Triose phosphate isomerase deficiency -TPI1, Glutaric acidemia type2-ETFDemia, cell anemia, Kitic fibrosis- CFTR, Glycine encephalopathy- AMT, Smith- Lemli- Opitz Syndrome- DHCR7, Epidermolysis bullosa dystrophica- COL7A1