PGS is a laboratory procedure that uses molecular techniques like Next Generation Sequencing, to reveal the number of chromosomes per embryo. Normal embryos have a total of 46 chromosomes arranged as 23 pairs of chromosomes, one of which is responsible for gender (XX for Female, and XY for Males). PGS is used to screen out embryos with abnormal numbers of chromosomes. An example is Down Syndrome in which there are 47 chromosomes (usually an extra chromosome 21) instead of 46. Chromosome abnormalities reduce the pregnancy rate, increase the chance of miscarriage, and may lead to major genetic disorders in the offspring.
Preimplantation Genetic Screening (PGS) is used to identify the number of chromosomes in the embryos. It is designed to look for chromosomal changes that may cause failure of embryo implantation, miscarriage, or syndromes such as Trisomy 21.
Preimplantation Genetic Diagnosis (PGD) is designed to look for disease-causing mutations such as Cystic Fibrosis, Huntington’s Disease, and Tay-Sachs among many others. PGD is tailored to each patient’s specific case. It is designed to eliminate (or greatly reduce) the risk of passing a harmful mutation from parent to their future babies.
DNA Xperts uses the latest technologies in genome sequencing to identify undesired mutations in your embryos. Our laboratory works closely with your IVF doctor to help you select healthy embryos for transfer.
FISH (fluorescence in situ hybridization), aCGH (array comparative genome hybridization) and NGS (Next Generation Sequencing) are the three main platforms available for preimplantation genetic screening.
FISH is the oldest technology used in PGS. FISH applies fluorescent labels to a specific region on 12 or fewer chromosomes. The embryos are fixed on a microscope slide, labeled, and observed under fluorescence microscopy for copy chromosome evaluation. Because FISH looks only at one specific location of the chromosome, large deletions and insertions are unlikely to be detected. Because it examines only a small fraction of chromosomes (usually five) it misses many potential problems.
Array CGH (aCGH) is similar to FISH in that it uses fluorescence detection, but it does so at a larger scale, ranging from thousands of probes (aCGH) to hundreds of thousands of probes (SNP array). Array CGH is the most common platform used in PGS and is substantially better than FISH. However, it is known to have several limitations resulting in an approximately 3% false positive and false negative rate.
NGS (Next Generation Sequencing) is the latest technology used in PGS. NGS reads the actual DNA sequence on each chromosome to directly determine the presence or absence of chromosomes, and can reach very high resolution allowing the detection of single mutations. Because NGS does not rely on fluorescence, the chance of false negative or false positive results is substantially reduced.
Your privacy is our priority. We don’t share patient information with any third party. Our protocols requires that your doctor’s office be the only party who directly receives your report. Your test results are submitted to your doctor directly by a dedicated team.
Your doctor will collect your sample in their clinic or lab and this sample will be sent over to DNA Xperts facility.
Project Design/Advice Assistance
Our PregaSight services are performed by a group of specially trained and experienced scientists in a streamlined workflow under the supervision of a qualified clinician. Please contact our technical support or genetic counselling team with details of your requirement or any questions you many have.