24-Chromosome Pre-Implantation Genetic Screening (PGS)

Pre-Implantation Genetic Screening (PGS) allows for the screening of embryos during In Vitro Fertilisation (IVF) in order to identify abnormalities in the chromosomes caused by aneuploidy . Viafet's Exact Comprehensive Chromosomal Screening, ExactCCS, screens all 24 chromosomes for aneuploidy, increasing your chances of achieving a healthy pregnancy and decreasing your risk of miscarriage by identifying embryos with the healthy number of chromosomes. With over 15 years of experience in Reproductive Genetics, during which over 15,000 samples have been tested, Viafet specialized in PGS.

What is Aneuploidy?


Our bodies are made up of cells containing chromosomes . Each chromosome holds genes that code for the proteins essential for healthy development. In humans, each cell normally has 46 chromosomes. These 46 chromosomes are made of up 22 pairs, one pair from each parent, and the sex chromosomes, X and Y (XX in females and XY in males), making a total of 24 unique chromosomes. For this reason, genetic testing such as ExactCCS™ is referred to as 24-chromosome screening.

Aneuploidy, what does it mean and how does it happen?

When an individual has more or less than 46 chromosomes, they are said to have a chromosomal abnormality due to aneuploidy , additional or missing chromosomes. Having an extra chromosome, 47 instead of 46, is known as a "trisomy", while having a missing chromosome, 45 instead of 46, is known as a "monosomy".

Aneuploidy can naturally occur either when the egg and sperm cells are being made or as cells multiply and divide during early embryo development and are not necessarily associated with family history. However, the likelihood of aneuploidy occurring in embryos increases with maternal age as ovarian reserve quality diminishes.

Aneuploidy and pregnancy

Most aneuploid embryos either do not implant or result in early pregnancy loss -- over 60% of pregnancy loss or IVF failure can be attributed to aneuploidy. However, some chromosomal abnormalities have a higher occurrence in developing foetuses and can result with a baby being born with an abnormal number of chromosomes. These include:

  • Trisomy 21 (Down syndrome)
  • Trisomy 18 (Edward syndrome)
  • Trisomy 13 (Patau syndrome)

Aneuploidy can also occur in the sex chromosomes, X and Y. These include:

  • Klinefelter syndrome (XXY)
  • Turner syndrome (X)
  • Triple X syndrome (XXX)
  • Jacob syndrome (XYY)

Viafet's 24-chromosome ExactCCS™ can detect all of the conditions mentioned above. In some instances, there are not entire additional or missing chromosomes but rather small portions of chromosomes called duplications and deletions. Viafet's ExactCCS™ is able to detect duplications and deletions down to 5MBase.

Where can I get testing?

Talk to your IVF physician about 24-chromosome PGS and if it right for you. If your physician does not yet offer Viafet testing, please suggest that they contact us - testing can get started immediately. If your physician is already offering Viafet testing, all coordination for your case will be completed between your IVF centre and Viafet's team.

With locations in the United Arab Emirates (Dubai and Abu Dhabi), Australia, the Kingdom of Saudi Arabia, Lebanon and more locations coming soon, Viafet's services are available to a wide network of clinicians and patients. If at any time during your journey you have questions or would like to speak with a Genetic Counselor, contact Viafet and we will schedule an appointment immediately.