Pre-implantation genetic screening (PGS) is a genetic test that may be performed during an IVF treatment. Addition or loss of chromosome in an embryo can result in abnormal development and possible miscarriages. Some chromosomally abnormal embryo may still produce a viable, full term pregnancy with a genetically abnormal child. However, this can be avoided.
PGS tests are designed to allow couples to screen the chromosomes of their embryos for possible abnormalities prior to implantation. An embryo with abnormal number of chromosomes is called aneuploid.
The typical example of a disease resulting from aneuploidy is Down’s Syndrome, referred to as trisomy 21. The rate of chromosome abnormalities is significantly higher in women in mid-thirties or more advanced in age.
Couples may consider PGS test in the cases below:
Chromosome abnormalities are one of the main factors causing recurrent miscarriages, or birth defects and mental retardation in live born babies. Genetic biopsy involves taking one or two cells from the embryo. All 23 pairs of chromosomes – the 22 non-sex chromosomes and sex chromosomes (X & Y) are then examined. The PGS tests we preform at our advanced San Diego laboratory identify chromosomally normal embryos and therefore increase the chance to conceive a healthy pregnancy.
Examples of chromosomal disorders:
Couples who have family history of genetic disease other than chromosome abnormality should consult with our physician to see if they qualify for PGD, preimplantation genetic diagnosis. PGD procedure identifies gene abnormalities as opposed to looking for full chromosome addition or deletion.