PREIMPLANTATION GENETIC DIAGNOSIS
In recent years, developments in genetics allow genetic analysis to be carried out on embryos
developed in vitro by in vitro fertilization methods and the placement of selected healthy embryos
in the uterus of the mother before pregnancy occurs. This method is called pre-pregnancy genetic
diagnosis (Preimplantation Genetic Diagnosis-PGD).
One of the most important application areas of the PGT technique embryos
that do not have a genetic disease but may not have a genetic disorder in their chromosomes.
These disorders are more common in women of advanced age (35 years and older). This
situation may result in infertility as it both reduces the chance of attachment of the embryo
(implantation) and may cause unwanted abortions. As a matter of fact, 40 out of every 100
pregnancies in women aged 39 and over have problems that occur due to a numerical
chromosomal disorder .
The aim of PGD is to increase implantation rates, reduce spontaneous abortions and increase
healthy baby birth rates by selecting chromosomally normal embryos. Indeed, the miscarriage
rate, which can reach up to 23 percent in normal pregnancy due to chromosomal disorders, may
decrease to 9 percent after PGD.
Pre-pregnancy genetic diagnosis is performed by taking 1 or 2 cells from embryos
developed as a result of fertilization of egg and sperm cells obtained from mother and father
candidates in laboratory environment. Special methods called Fluorescence In Situ Hybridization
(FISH), Microarray-based comparative genomic hybridization (aCGH) or Polymerase Chain
Reaction (PCR) are used for genetic diagnosis. Diagnosis of numerical chromosomal disorders
such as monosomy or trisomy (Down syndrome and other trisomies) and single gene diseases
(such as hemophilia, Mediterranean anemia, cystic fibrosis, muscular dystrophies) in the baby to
be born is possible with PGD. Thus, healthy babies are born by transferring disease-free, healthy
embryos to the expectant mother.
DIAGNOSIS BEFORE PREGNANCY
• In couples with a genetic or hereditary disease carrier,
• In couples who have a child or children with a previous genetic disease,
• For the purpose of HLA genotyping (tissue typing),
• In the identification of diseases showing genetic predisposition (tendency)
• Women in the advanced age group (37 years and over) who have been accepted for assisted
• In couples with recurrent early pregnancy miscarriages,
• In couples who could not achieve pregnancy with assisted reproductive techniques despite
multiple applications or who lost their pregnancy due to miscarriage,
• It is applied in cases of chromosomal disorders or genetic diseases associated with severe male
HOW IS THE PGT TEST DONE?
• Whether the patient is suitable for PGD is evaluated by the reproductive health specialist,
genetic counselor and the doctor of the related disease.
• The couple is prepared for the IVF procedure.
• The egg taken from the mother is fertilized in the laboratory with the sperm taken from the
• 1-2 blastomere cells are removed from the obtained embryo by biopsy by embryologists.
• Cells obtained by biopsy are prepared and tested according to the method to be
• Embryos with genetic diseases or chromosomal disorders are selected and discarded and
healthy embryos are transferred to the mother's womb.