PGT What Is Preimplantation Genetic Testing

Learn More On Preimplantation Genetic Testing

Preimplantation Genetic Testing is a reproductive technology used along with an IVF cycle to increase the potential for a successful pregnancy and delivery of a healthy child.

PGT is a genetic test on cells extracted from  5-6 days old embryos ( called blastocyst stage ), to help select the best embryo(s) in order to achieve  higher pregnancy rate , reduce the miscarriage rate and also to avoid a genetic disease in the baby if either one or both parents are known to be a carrier of a specific genetic disease.

  • PGT-A ( A=aneuploidy ) screens for all the 46 chromosomes in the embryo for any abnormalities in their numbers e.g Down’s Syndrome with additional Chromosome 21 or Turner’s Syndrome  with absent chromosome X .
  • PG-M ( M= Monogenic , previously known as PGD ) is to detect a specific disease in the embryo when  there is a 25% – 50% chance to have a child affected with a specific genetic disease e.g Thalassemia . PGT-M can identify which embryo(s)are affected, unaffected, or a carrier (if applicable) for that disease before we transfer the embryo into the uterus for a pregnancy.
  • PGT-SR( SR = Structural rearrangement ) can identify which embryos have an abnormal amount of chromosomal material in cases such as translocation or deletion of a segment of chromosome which can result in unbalanced amount of genetic material resulting in recurrent miscarriages .

NICS

PGT-A requires biopsying a few cells from the trophectoderm of embryo , which requires specialized skills and creates false positives and negatives because chromosome numbers in the trophectoderm ( the future fetal placenta ) and the inner cell mass ( the future fetus ) are not always the same .

With the use of niPGT-A ( non invasive PGT-A ) , Ever Link Fertility Centre offers a solution to these problems .

Ever Link Fertility Centre is one of the first clinic in Asia to provide NICS-A  , which is a non invasive technology of genetic testing without removing any cells from the embryo , hence minimising any possible damage to the embryo.

What is the ERA ?

The ERA (Endometrial Receptivity Analysis) is a genetic test that evaluates the expression of genes to determine whether the endometrium ( uterus lining ) is developed into a receptive endometrium to increase the chances for an embryo to implant . The timing of embryo transfer ( whether Day 3 embryo or Day 5/6 blastocyst ) is based on the small window of time which is called ‘window of implantation’ ( WOI ) that is optimal and most of the women this window is in the expected time based on the ultrasound and blood hormone test and the timing when the Progesterone hormone is introduced . This is to ensure that the endometrium and the embryo(s) are synchronized However , some women have a unique “window of implantation” that requires the standard embryo transfer timing protocols to be altered.

Tissue is obtained from an endometrial tissue sample collected from the uterus through a procedure called an endometrial biopsy. After hybridization, the signal intensities are read by a computerized predictor and the sample is classified as “Receptive” or “Non-Receptive” according to its specific expression profiles.

As WOI is not the same in all women ,ERA tests can reveal a need for a change in the timing of embryo transfer and permits personalised embryo transfer (pET) timing based on an individual’s results.