Preimplantation Genetic Diagnosis
The Phoenix PGD center
The goal of Arizona Reproductive Medicine Specialists (ARMS) is to assist couples in their efforts to conceive healthy children. Over the past two decades, advances in the Assisted Reproductive Technologies of reproductive medicine and the Molecular Genetic DNA Diagnostic Technologies of clinical genetics have emerged to assist in the process of conceiving healthy children through the development of Preimplantation Genetic Diagnosis (PGD).
The Phoenix Preimplantation Genetic Diagnosis Center was established with the purpose of helping couples who are at increased risk for producing children with incurable genetic diseases or chromosomal disorders to achieve their goals of having healthy children.
The Phoenix Preimplantation Genetic Diagnosis Center collaborates with two internationally recognized molecular genetics pioneers and experts in the field of Preimplantation Genetic Diagnostics: Mark R. Hughes, M.D., Ph.D. of Genesis Genetics Institute and Santiago Munne, Ph.D. of Reprogenetics. We collaborate with these internationally recognized laboratory PGD experts to provide our patients the highest quality assurance for precise and accurate genetics diagnostics in their embryos. The Phoenix Preimplantation Genetic Diagnosis Center is the most experienced leader in providing excellence and the highest quality assurance in embryonic genetic disease diagnostics in the Southwest.
What is PGD?
Preimplantation Genetic Diagnosis (PGD) is the screening and detection of genetic diseases or chromosome abnormalities in eggs or embryos prior to establishment of an intrauterine pregnancy in order to produce healthy children. The advantage of PGD is that couples at increased risk for producing children with incurable genetic diseases or chromosomal disorders are provided the opportunity to reproduce without the increased risk of having a child with an incurable disease or chromosomal abnormalities.
The PGD process is accomplished by initially removing one or two cells from early embryos as they develop in culture in the in vitro fertilization (IVF) laboratory. These cells undergo genetic analysis to determine which embryos are chromosomally normal or are not affected with the specific genetic disease under study. Results of the PGD testing are available within two days and only those embryos determined to be chromosomally normal or not affected with genetic disease are transferred into the uterus to establish a pregnancy.
PGD for genetic disease is able to be performed for a majority of single gene disorders in which the disease gene mutation has been identified. PGD screening of embryos for possible chromosome abnormalities involved in fetal abnormalities such as Down syndrome and miscarriages is performed by analyzing all of the chromosomes in the embryo cells.
Who is PGD for?
PGD, or genetic testing performed on eggs or embryos, is a valuable adjunct to the process of IVF. Although it may become a routine part of the IVF process in the future, currently PGD is available as a reproductive option for couples in three general categories.
1. PGD may be an option for a couple when an individual partner is a carrier, or both partners are determined to be carriers for an inheritable genetic disease (e.g. cystic fibrosis, sickle cell anemia, Tay Sachs disease, etc.) and the risk of producing a child with an incurable genetic disease is 25% to 50%.
2. PGD may be an option for couples who are at increased risk for producing abnormal embryos with an abnormal number of chromosomes (aneuploidy), such as women of increased reproductive age and in couples with unexplained recurrent miscarriages. As women progress through normal ageing, they produce an increased rate of eggs with abnormal number of chromosomes or aneuploidy. Fertilization of eggs with an abnormal chromosome complement results in aneuploid embryos with abnormal numbers of chromosomes. Aneuploid embryos frequently result in failed implantations and reduced fertility, or miscarriages before 13 weeks gestation, and less frequently, fetuses with aneuploidy such as Down syndrome. The rate of aneuploidy in eggs from women older than 40 years is greater than 50%. Genetic testing to differentiate the embryos with a normal number of chromosomes from the embryos with an abnormal number of chromosomes in embryos reduces the possibility of having an abnormal pregnancy. PGD screening for aneuploidy, otherwise referred to as preimplantation genetic screening (PGS), increases the chance for producing a normal pregnancy and reduces the risk of early pregnancy loss and pregnancies affected with fetal aneuploidy such as Down syndrome.
3. Couples in which one of the partners is a carrier for a chromosome rearrangement, such as a balanced translocation or inversion, are at increased risk to produce chromosome abnormalities in their embryos resulting in increased rates of miscarriages and fetal abnormalities. PGD may be an option for these couples since it has been shown to improve outcomes in pregnancies conceived from carriers of balanced chromosome rearrangements.
Why consider PGD?
Couples at increased risk for producing children with incurable genetic diseases or chromosomal disorders have the option of conceiving pregnancies and undergoing prenatal diagnosis to determine if their fetus is affected with a specific genetic disease or chromosomal disorder. The problem with prenatal diagnosis is that it is performed after a pregnancy is established, and if it is determined that a fetus is affected with a specific genetic disease or chromosomal disorder, the couple must confront the difficult decision of having an affected child or pregnancy termination. The methods of prenatal diagnosis are chorionic villus sampling performed between 10-12 weeks of the first trimester, and amniocentesis performed after the fifteenth week of the second trimester. Although first trimester biochemical and ultrasound testing is available to assist in determining pregnancies at highest risk for chromosome abnormalities, they are still considered screening tests and are not yet confirmatory diagnostic tests.
Besides PGD and prenatal diagnosis, other reproductive options available for couples with increased genetic reproductive risks are the use of donor eggs or donor sperm and adoption. PGD is safer than elective second trimester termination, psychologically more acceptable than elective termination, and it provides couples at increased risk for producing children with incurable genetic diseases or chromosomal disorders with more reproductive options than: donor eggs or donor sperm, adoption, and sterilization.
Couples considering PGD should initially consult with a Board Certified Clinical Geneticist or Genetic Counselor to review their family histories and help the couple understand their genetic reproductive risks. Our Phoenix PGD Center has a physician who is a Board Certified Reproductive Endocrinologist and a Board Certified Clinical Geneticist, Dr. Johnson, available for pre-PGD or PGS counseling.
Couple has a baby with IVF and PGS after seven years of fertility treatments
*View Fertility Success Rates for more information on ongoing pregnancy rates