Pre-implantation Genetic Diagnosis (PGD)
PGD or Pre-implantation Genetic Diagnosis, a relatively old technology that has recently increased in popularity, can test for either a specific gene abnormality such at Tay Sachs or Cystic Fibrosis; or it can test for an irregular arrangement in the normal chromosome count (aneuploidy). Normally our genetic material is arranged on chromosomes. We each have 23 pairs of chromosomes. When we are conceived, each of the two cells, the sperm and egg, has a single set of chromosomes. When the sperm penetrates the egg, the job of the egg is to bring these chromosomes together so there are 23 pairs. As we get older, the architecture inside the egg gets older and is not as proficient as when it is younger in bringing these two sets together, so there is an increased chance of having an irregular number of chromosomes in the developing embryo.
Embryo BiopsyWe call this irregular number of chromosomes Aneuploidy. Down’s Syndrome is the most famous form of aneuploidy, when there is a normal compliment of chromosomes, 23 pairs plus and additional number 21 chromosome resulting in “trisomy,” or three sets of Chromosome 21. PGD testing can test for the 9 or 12 most common forms of aneuploidy, reducing the chances for aneuploidy by up to 90%.
PGD is usually performed on the third day after egg retrieval. At this point there are usually there are between 4 and 8 cells in the developing embryo. Our embryologist delicately removes one cell from each of the developing embryos, fixes them to a slide and couriers the biopsies to our affiliate, Reprogenetics (the most experienced cytogenetics laboratory in the world.). Reprogenetics will stain the cells for the 9 most common chromosomal abnormalities, which make up 90 % of aneuploidies. (Not all of the chromosomal abnormalities are tested for.)
This is an example of the staining technique called FISH, which allows us to determine which embryo has an irregular number of the tested chromosomes.That information is relayed back to us and the good embryos are then used for embryo transfer.
The number one cause of infant deaths in the U.S. has genetic implications. (2001, Data from National Center for Health Statistics CDC). 7% of stillbirths and neonatal deaths have chromosomal abnormalities. (Patients Fact Sheet Genetic Screening for Birth Defects, ASRM 2002).
Recurrent miscarriages and repetitive failed IVF may be due to genetic abnormalities. Preimplantation genetic diagnosis (PGD) can be used as a diagnostic procedure to identify embryos that carry genes for certain diseases.
PGD is performed by genetically analyzing a single cell biopsy from each embryo. Only embryos classified as normal will be transferred back into the woman’s uterus.
“The advantage of accurately diagnosing these genetic abnormalities in the embryo obviates the 25% to 50% risk of transferring an affected embryo with the specific abnormality in question.” (A Practice Committee Report: Preimplantation Genetic Diagnosis, ASRM. June 2001).
Embryo Biopsy
PGD is usually performed on the third day after egg retrieval. At this point there are usually there are between 4 and 8 cells in the developing embryo. Our embryologist delicately removes one cell from each of the developing embryos, fixes them to a slide and couriers the biopsies to our affiliate, Reprogenetics (the most experienced cytogenetics laboratory in the world.). Reprogenetics will stain the cells for the 9 most common chromosomal abnormalities, which make up 90 % of aneuploidies. (Not all of the chromosomal abnormalities are tested for.)
This is an example of the staining technique called FISH, which allows us to determine which embryo has an irregular number of the tested chromosomes.
The number one cause of infant deaths in the U.S. has genetic implications. (2001, Data from National Center for Health Statistics CDC). 7% of stillbirths and neonatal deaths have chromosomal abnormalities. (Patients Fact Sheet Genetic Screening for Birth Defects, ASRM 2002).
Recurrent miscarriages and repetitive failed IVF may be due to genetic abnormalities. Preimplantation genetic diagnosis (PGD) can be used as a diagnostic procedure to identify embryos that carry genes for certain diseases.
PGD is performed by genetically analyzing a single cell biopsy from each embryo. Only embryos classified as normal will be transferred back into the woman’s uterus.
“The advantage of accurately diagnosing these genetic abnormalities in the embryo obviates the 25% to 50% risk of transferring an affected embryo with the specific abnormality in question.” (A Practice Committee Report: Preimplantation Genetic Diagnosis, ASRM. June 2001).
Advanced Reproductive Center of Hawai‘i
Kapiolani Medical Center Office Building •
1319 Punahou Street Suite 520 •
Honolulu, Hawaii 96826Phone (808) 949-6611 • Email archawaii1@yahoo.com • Visit Our Office