PGT refers to obtaining information about the genetic and chromosomal makeup of an embryo or egg prior to implantation.
The goals of testing include improvement of the chances of pregnancy within an embryo transfer cycle, lowering the risk of having a miscarriage and increasing the likelihood of having a healthy baby. PGT can test for numerical chromosomal abnormalities such as Down’s syndrome, trisomies (having an extra chromosome), sex chromosomal abnormalities, monosomies (missing a chromosome) and single gene disorders such as cystic fibrosis, sickle cell disease, and many others. PGT can also identify the gender of the embryo.
PGT does not test for all genetic disorders, syndromes, autism, developmental problems or birth defects. It also does not guarantee the health of the embryo, implantation, clinical pregnancy or a live birth.
PGT-A (Preimplantation Genetic Testing for aneuploidy)
It is used to diagnose numerical abnormalities (aneuploidies). These may be duplications or deletions (loss of a DNA fragment) of specific chromosomal areas. This term substitutes the old PGS (Preimplantation Genetic Screening). With this test, chromosome losses or additions are detected in embryos and, so, related diseases. Some examples are Down, Turner and Klinefelter syndromes.
PGT-M (Preimplantation Genetic Testing for monogenic diseases):
Helps to detect hereditary diseases caused by mutation or alteration of an only gen in the DNA sequence. Some examples are cystic fibrosis and sickle-cell anemia. If parents are aware of specific genetic diseases in themselves or family members prior to embryo implantation, IMAART USA IVF can include the PGT-M test to your IVF proposal to reduce new-born health risks.
Candidates for PGT-M (PGD) Include:
Carriers of Single-Gene Disorders
Carriers of Sex-Linked Disorders
Patients with Chromosomal Disorders
Women Aged 35 and Older
Patients Who Have Had Multiple Miscarriages
Those with Multiple Failed Fertility Treatments
PGT-SR (Preimplantation Genetic Testing for structural diseases):
It is used to diagnose structural abnormalities i.e., those that affect the structure of one or several chromosomes. This can happen by rupture or incorrect union of chromosomal segments. Translocations are abnormalities in which a chromosome is broken and a fragment is attached to another chromosome. Embryos that inherit this translocation could lead to babies that could be infertile in adulthood.
A SR abnormality may result in your child being developmentally delayed, having learning disorders, being physically challenged, or you could be at higher risk for your pregnancy to end in a miscarriage. These issues can be due to the fact that one of the partners can be a carrier of a “chromosomal inversion”, reciprocal translocation or Robertsonian translocation.
The main benefit PGT in In Vitro Fertilization (IVF) practices is its ability to diagnose any numerical abnormalities (aneuploidy) in the embryos because it analyses all 23 pairs (46 chromosomes). Most miscarriages are due to chromosomal abnormalities of the embryos which can be diagnosed by PGT and only chromosomally normal embryos can be transferred into the uterus.