Preimplantation Genetic Diagnosis
What is PGD/S?
Preimplantation Genetic Diagnosis (PGD), also known as Preimplantation Genetic Screening (PGS), refers to a reproductive technology procedure performed on embryos prior to implantation and pregnancy to detect chromosomal/genetic normalcy. The procedure is based upon the removal of cell(s) from an embryo on day 3 or 5 after fertilization.
PGD/S is a way for couples to prevent a pregnancy affected by a genetic condition or chromosomal disorder, another way of prenatal diagnosis. This procedure is performed after a woman’s eggs has been retrieved and fertilized by sperm, thus always adjunct to assisted reproductive technology.
Depending on the need, there are various types of PGD/S available. While FISH (Fluorescent In-Situ Hybridization) based PGD/S has been the standard in PGD/S in the past, only a fraction (up to 12) of the chromosomes can be looked at with this technology. Reliability and accuracy of these tests has been the subject of major controversy which has recently limited the usefulness and application of FISH based testing.
Micro Array technology is a cutting edge approach that allows screening of all 23 pairs of Chromosomes. This technology may be accomplished by using Single Nucleotide Polymorphisms (SNP) or Array Comparative Genomic Hybridization (aCGH). These technologies use a molecular approach to determine chromosomal normality (euploidy). La Jolla IVF participated in the development of the first routinely available Array based PGD/S. The biopsy technique remains the same, regardless of the molecular approach applied. We are now offering Day 5 blastocyst biopsy with fresh Day 6 embryo transfer, a new approach that was recently recognized at the 2011 American Society of Reproductive Medicine’s national meeting as a significant advancement in PGD/S technology.
Since implementing our new PGD biopsy procedure in September 2011,
PGD/S on Day 5 with a fresh embryo transfer on Day 6,
we have had an impressive clinical pregnancy rate of 84%.
In our hands, PGD has proven to be an extremely valuable tool to increase pregnancy and live birth rates.
These emerging technologies are enabling thousands of couples around the world to fulfill their dreams of having a healthy offspring and La Jolla IVF is very proud to be involved in the development of, as well as the participation in, these newly validated and effective procedures.
In fact, the first three babies born in the world from the SNP technology were from La Jolla IVF. Please see their photos below.
As all women have a risk to have a pregnancy with chromosome abnormalities, this risk does increase in relation to the woman’s age. With PGD/S a patient of advanced maternal age would have the option of analyzing the chromosomal integrity of their embryos prior to implantation and therefore less likely to be faced with potentially difficult decision making during an ongoing pregnancy. The parents can pursue PGS for aneuploidy, an embryo the wrong number of chromosomes such as Down syndrome (an extra chromosome 21), to optimize the chance of having a healthy baby.
Also some of our patients who experienced prior pregnancy loss want their embryos tested as chromosomal abnormalities are the most common cause of miscarriage. 50% of first trimester miscarriages are due to a chromosome abnormality. From time to time we also have patients with a family history of inherited genetic disorders who need to have their embryos analyzed to exclude any affected embryos being transferred.
Examples of Chromosomal disorders diagnoses by PGS
- Autosomal Trisomies (i.e., Down’s Syndrome)
- Autosomal Monosomies
- X, Y Numerical Disorders (Turner’s Syndrome, Kleinfelter’s Syndrome)
- Translocations (Reciprocal or Robertsonian)
Examples of Genetic disorders diagnoses by PGD
- Cystic Fibrosis
- Duchenne Muscular Dystrophy
- Hemophilia A
- Retinitis Pigmentosa
- TaySachs Disease
- Sickle Cell Anemia
- 119 Others