PGD - Preimplantation Genetic Diagnosis  Huntington Reproductive Center

Our PGD (preimplantation genetic diagnosis) Web site contains extensive information on all aspects of preimplantation genetic diagnosis. The PGD site is divided into several sections including: a detailed description of PGD, PGD and genetic disease, history, success rates and gender selection. Our other sites include the Huntington Main site,which contains detailed infertility diagnostic and treatment information, the Huntington IVF Web site, the Clomid Web site, and our recently launched Spanish language site .

Our infertility clinic focuses on introducing and perfecting new infertility procedures and techniques, such as PGD, ICSI, and others that are on the cutting edge of reproductive medicine. Huntington Reproductive has extensive preimplantation genetic diagnosis experience having performed over 399 cases with a 45% pregnancy rate. Our PGD center has performed thousands of successful cases since the procedure was first offered.

PGD - Overview

PGD is conducted as a procedure during an in vitro fertilization cycle. The female undergoes ovulation induction with FSH to develop many eggs. These eggs are withdrawn transvaginally and combined with the partners sperm. The resultant embryos are cultured from 3-5 days during which time the preimplantation genetic diagnosis procedure is conducted.

PGD involves screening embryos using fluorescent in situ hybridization (FISH) and/or the polymerase chain reaction (PCR). Using FISH the chromosomes within the polar body are labeled with probes making it possible to identify those with an abnormal number of chromosomes, broken chromosomes, or translated chromosomes. In cases involving more subtle abnormalities, on the scale of single genes or even DNA bases or single gene diseases, highly specialized techniques such as PCR are required.

Such methods rely on the fundamental principles of the genetic code, and specifically on the cell's ability to generate a matching, or complementary segment of DNA. PGD can be used to screen many genetic diseases. Some couples are at known risk for transmission of specific genetic diseases to their children. These diseases include Down's Syndrome, Trisomy 21, Tay Sachs Disease, hemophilia A and B, Gaucher's Disease, Sickle Cell Anemia, and many others. Some genetic diseases can only occur in a child of a specific gender. PGD allows the identification of the embryo's sex so that only unaffected ones will be transferred to the uterus.

PGD is also used for gender selection when a couple desires a child of a particular sex. Oftentimes, couples have children of one sex and want to experience the joy of raising a child of the other gender. The embryos are biopsied and only the ones of the chosen sex are placed into the uterus.

Microsort is another technique offered for gender selection. The Huntington Reproductive Center, in partnership with the Genetics and IVF Institute in Fairfax, began investigating this technology in the early 1990's as part of an ongoing FDA clinical trial. Microsort® technology is only available at these two locations. Microsort gender selection technology improves the chance of a female pregnancy to 89.5 percent after sorting. For a male, MicroSort® improves the success rate to 73.6 percent. PGD success rates for gender selection approach 100%; however, PGD is more expensive than Microsort® .

PGD is useful for screening many genetic diseases that are sex linked meaning they can only occur in a particular gender. For example, hemophilia A and B are generally X linked recessive and occur in males. In these cases, it is used to ensure that only female embryos are transferred to the uterus, thus avoiding transmission of hemophilia. It can be used for screening in cases of advanced maternal age where certain genetic diseases are more common. Preimplantation genetic diagnosis is also offered to couples in which one of the members has a rearrangement of their chromosomes, or a balanced translocation.

PGD-Results

PGD results are usually available within 48 hours after blastomere biopsy which corresponds to day 5 after egg retrieval. At this time embryos, depending on their original quality, may, or may not, reach the final stage of in vitro development (blastocyst stage). Usually on day 5, according to the results of the specific genetic test, only embryos free of tested genetic defects will be transferred into the patient.