What is the Difference Between PGS and PGD?

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The main difference between Preimplantation Genetic Screening (PGS) and Preimplantation Genetic Diagnosis (PGD) lies in their purposes and the specific genetic abnormalities they target. Both PGS and PGD involve the analysis of biopsied cells from an embryo to screen for or diagnose genetic abnormalities before implantation, but they are used for different reasons and in different scenarios.

PGS:

  • Analyzes biopsied cells from the embryo to screen for potential genetic abnormalities when there are no known potentially inherited disorders.
  • Also known as Comprehensive Chromosome Screening (CCS) in some cases.
  • Evaluates the number of chromosomes in the embryo to identify abnormalities that can lead to miscarriage or genetic diseases.
  • Recommended for parents with no known genetic abnormalities, female partners aged 38 or older, couples interested in single embryo transfer, gender selection, history of pregnancy loss, or history of failed IVF/implantation failure.

PGD:

  • Detects a specific disorder that has a high probability of being passed down from parents to their offspring.
  • Focuses on testing one particular chromosome or gene.
  • Used by couples who know they have or carry a genetic disease and know their gene mutation.
  • In some cases, PGD patients can also benefit from PGS, as it helps identify embryos that did not inherit the specific genetic disorder.

Both PGS and PGD are done in the IVF lab and are considered safe, with some minor risks to the embryo. The choice between the two testing options should be made in consultation with a fertility specialist based on individual fertility history and needs.

Comparative Table: PGS vs PGD

Preimplantation Genetic Screening (PGS) and Preimplantation Genetic Diagnosis (PGD) are two types of genetic testing used during in-vitro fertilization (IVF) to screen and diagnose embryos for genetic and chromosomal abnormalities. Here is a table summarizing the differences between PGS and PGD:

Feature PGS PGD
Purpose Identifies chromosomally abnormal embryos to improve the chances of successful pregnancy in IVF. Identifies embryos with specific genetic mutations or abnormalities, such as Cystic Fibrosis or Huntington's Disease.
Testing Screens for chromosomal abnormalities in all 24 chromosomes. Screens for specific genetic mutations or abnormalities.
Accuracy Both procedures are 99.9% accurate. Both procedures are 99.9% accurate.
Turnaround Time Results can take between 12 hours to 30 days. Results can take between 12 hours to 30 days.

Both PGS and PGD testing can increase the chances of a successful pregnancy and significantly lower the risk of genetic diseases in the offspring. PGS is available to all patients undergoing IVF, while PGD is recommended for couples who know they have or carry a genetic disease and know their gene mutation.