Preimplantation Genetic Diagnosis ( PGD) – Genetic Embryo Testing at Dallas IVF

Preimplantation genetic diagnosis (PGD), offered by Dr. Barnett at Dallas IVF, is a revolutionary advance in reproductive medicine. PGD enables Dr. Barnett and his embryology staff to test an embryo at the ARTS laboratory near Dallas IVF for genetic problems before placing it back into a woman’s uterus during an in vitro fertilization (IVF) cycle. Usually, multiple embryos are tested and only those that are found to be healthy are implanted.

Prior to PGD becoming available, women at high risk for having an affected child would only have the option of waiting until they were pregnant before any testing of the fetus could be performed. Women would undergo chorionic villi sampling (CVS) or amniocentesis, and then have to make the difficult decision of whether to terminate a pregnancy. In addition, CVS and amniocentesis have associated risks and can cause women to miscarry an otherwise healthy pregnancy.

Preimplantation genetic diagnosis does not guarantee that a healthy child will be born and is not 100 percent accurate. It only tests for specific genetic or chromosomal problems commonly associated with miscarriages, balanced translocations, or single gene diseases. Many children born with severe or fatal birth defects have completely normal chromosomes. PGD has been demonstrated to increase the chance that a woman with a history of recurrent pregnancy loss may be able to deliver a healthy child. In addition, it has been demonstrated to limit the possibility of a woman delivering a child with specific genetic defects.

The Preimplantation Genetic Diagnosis Process

PGD at Dallas IVF is performed at the outstanding assisted reproduction laboratory at Presbyterian Hospital in Plano, with which we are members. The most common type of PGD procedure performed at the Presbyterian Hospital ART Program in Plano is the biopsy of a single blastomere from a six- to eight-cell embryo. As the embryo divides, a one-cell embryo splits into a two-cell embryo, which then becomes a four-cell embryo and, if it is still healthy a day later, an eight-cell embryo. An eight-cell embryo is usually formed three days after the egg retrieval. A blastocyst, which is about one hundred cells in number, is formed on day five, the day of the embryo transfer. With PGD, our embryology staff, commonly takes one of the blastomeres, which is one of the cells of an eight-cell embryo, and uses that cell for testing (the embryo will regenerate the lost cell). The results are then made available by the time of embryo transfer two days later, on day five.

For some genetic problems, our embryology staff will discuss with you polar body biopsies, which can provide additional information. This test is performed when the mother has the genetic issue under investigation. Polar bodies arise from the oocyte (egg) as part of their final division and can offer further genetic information.

Contact Dallas IVF today to schedule your appointment with Dr. Barnett. He is happy to answer any questions you may have about PGD as well as the many fertility treatments he offers.

Types of PGD Available at Dallas IVF:

Aneuploidy Screen (Fluorescent In-Situ Hibidization, FISH) - Some women are at increased risk for having embryos with abnormal chromosomes. As women age, they are at higher risk for having Down Syndrome babies and miscarriages because of chromosomally abnormal embryos. Abnormal embryos include those with too many chromosomes or chromosomes that are missing parts. Genetically normal embryos contain 46 chromosomes, 23 from the father’s sperm and 23 from the mother’s oocyte, or egg. With PGD, our laboratory near Dallas IVF can help determine whether embryos contain an abnormal number of chromosomes. Fluorescent in-situ hibidization, or FISH, is the procedure used to test embryos for this. During this test, fluorescent markers bind to specific chromosomes so that they can then be seen under a special microscope. For example, in testing for Down Syndrome, an affected embryo would light up with an extra chromosome 21. Normal embryos have two number 21 chromosomes, but a Down Syndrome embryo would have three. FISH probes are available for testing the ten most common chromosomes associated with miscarriage, failed implantation and Down syndrome.
Single Gene Disorder - This includes an increasingly large number of inheritable diseases that can be tested for each year. Couples who are at an increased risk of having a child with cystic fibrosis, Tay Sachs, and sickle cell disease are in this category. Unlike the chromosomal abnormalities discussed above, which may involve an extra or missing chromosome, single gene disorders involve a mutation in one specific gene within a chromosome. Specific markers are made for the disease in question, and the embryos are tested with these same markers.
Translocation - Some couples are at risk for having recurrent pregnancy losses because either the husband or wife has a rearrangement of their chromosomes. These individuals have the correct number of chromosomes, but one part of one chromosome has been moved to another chromosome. The parent who has the translocation has what is called a ‘balanced translocation,’ but the embryo may have too much chromosomal material or not enough chromosomal material and is determined to be ‘unbalanced.’ Unbalanced embryos are at a very high risk for miscarriage, still-birth, or failure to implant. Specific markers can be made for the translocation that the parent has, and each embryo in an IVF cycle can then be tested to avoid transfer of an ‘unbalanced’ embryo.

Contact Us for Embryo PGD at Dallas IVF

Contact Dr. Brian D. Barnett today for more information about embryo PGD at Dallas IVF. Dr. Barnett is committed to helping you conceive a healthy child and utilizes the most advanced testing methods and infertility treatments available to achieve this goal.

Brian D. Barnett, MD
Presbyterian Hospital of Plano
MOB 3, Suite 334
6124 West Parker Road
Plano, Texas 75093

Phone: (972) 981-8700
Fax: (972) 981-8708
MAP

Contact Dr. Barnett today for more information about embryo PGD at Dallas IVF.