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 in approximately 80% of 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 , about 20% (1 out of 5) of 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.