PREIMPLANTATION DIAGNOSIS SCREENING


Pre Implantation Genetic Diagnosis (PGD)
PGD refers to the sophisticated scientific method of screening single cells from embryos to identify genetic defects and chromosomal disorders within embryos created using In Vitro Fertilization (IVF) such that they are not transferred to the child. The testing is done after IVF, prior to the transfer of embryo into the uterus. It is done when one or both of the genetic parents are known to have a genetic abnormality and the test is performed to check if the embryo carries the genetic defect. It offers the couples an opportunity to select healthy, disease- free embryos for implantation.

Ideal Candidate for PGD
Preimplantation Genetic Diagnosis can help

  • Couples with presence of chromosomal translocations
  • Couples with family history of X-linked chromosomes
  • Carriers of autosomal recessive disease
  • Carriers of autosomal dominant disease

Conditions diagnosed using PGD
PGD can help in the diagnosis of the following genetic disorders

  • Sex linked disorders include haemophilia, most neuromuscular dystrophies, Rett syndrome and hundreds of other diseses.
  • Single Gene defects resulting from single mutated gene. The most common diseases are Cystic fibrosis, Tay Sachs, Thalassemia, Myotonic Dystrophy etc.
  • Chromosomal disorders such as balanced translocations, inversions, deletions etc.
PGD can also be used to determine the sex of the embryo prior to transfer to the womb.

Pre Implantation Screening (PGS)
PGS is used to screen embryos for aneuploidy (missing or additional number of chromosomes) which may lead to implantation failures or miscarriages. In contrast to PGD, it is done when the genetic parents are presumed to be genetically normal. The main goal is to identify chromosomally abnormal embryos so that they are not transferred to the womb.
PGD and PGS provide an alternative to post-conception diagnostic procedures such as amniocentesis, chorionic villus sampling etc which is followed by pregnancy termination in case of unfavourable results.
Ideal Candidate for PGS

  • Women above 35 years of age
  • Couples with history of recurrent miscarriages
  • Couples with history of repeated IVF failures
Both PGD and PGS involve testing the cells of the embryo prior to transfer. Several cells are removed from the trophectoderm or the cells that are intended to be the placenta of a blastocyst (5-6 day old embryo). These cells are tested for abnormalities. At this stage all the embryos have the same genetic constitution and the potential for development. After testing, based on absence of irregularities, embryos are transferred.
The benefits include increased chances of pregnancies with decreased chances of multiple births, genetic defects or pregnancy loss
If you are considering PGD, talk to our genetic counselor or fertility specialist to know more about the process.



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