When patients going through in vitro fertilization (IVF) are known carriers of a specific, heritable genetic disorder or have a genetic disorder evident in their family backgrounds, they may choose preimplantation genetic diagnosis (PGD) or screening (PGS). At our FIRM IVF laboratory, embryos that are free of genetic disorders are implanted in the woman’s uterus in IVF. PGD can decrease the chances of passing on the condition to your unborn child, as well as decrease the chances of failed implantation or pregnancy. These genetic tests can identify many genetic disorders, including:
- Cystic fibrosis
- Sickle cell anemia
- Tay-Sachs disease
- Duchenne muscular dystrophy
- BRAC 1 and BRAC 2 mutations
- Fragile X syndrome
- Huntington’s disease
- Hemophilia A
PGS is another type of genetic testing that can be performed on IVF embryos created by parents without known genetic or chromosomal conditions. Rather than diagnosing a single condition, this is a broad screening test that looks for chromosomal abnormalities and can detect the sex of an embryo. PGS can help improve live birth rates using single embryo transfer since the embryo being transferred into the uterus is known to be genetically normal. It also reduces the risk of miscarriage.
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In the PGD test, an embryologist will biopsy the embryos created during an IVF cycle on day 5 or day 6 of development, and determine which embryos are unaffected by the genetic disorder present in the patient’s medical history. During embryo transfer, only the unaffected embryo(s) would be placed in the woman’s uterus. The other embryos can be frozen, stored, used in research (with the patient’s approval), or destroyed along with the embryos showing a genetic disorder.
Genetic testing will reveal the sex of each embryo, making it possible to reduce the risk of passing on sex-linked conditions, such as Duchenne muscular dystrophy. According to the Ethics Committee of the American Society for Reproductive Medicine (ASRM), the only acceptable use of preimplantation sex selection is when trying to avoid passing on a known, sex-linked genetic disorder.
Who Should Consider PGD?
The PGD is a good guide to a couple’s risk of having and passing on a genetic disorder. The geneticist should be able to identify if the man, woman, or both are at-risk for carrying a genetic disorder. If a heritable condition is known in the patient’s family, or if a previous child was born with a genetic disorder, a couple may consider PGD. This can help minimize the risk of passing on the condition, as well as the risk of implantation and/or pregnancy failure before live birth.
Single gene disorders can be inherited mutations known to cause a disease, such as cystic fibrosis. Gene disorders can also cause a specific characteristic due to abnormalities in chromosome structure, such as gender-related problems or the inherited genetic BRAC 1 and BRAC 2 mutations that predispose a woman and her offspring to breast and ovarian cancer. Parents do not have to have a genetic disease or characteristic to pass it on to their offspring. Consequently, many people are not aware that they are at risk for carrying a genetic disorder. Usually, parents have a discussion with a geneticist about the family background of each parent, identifying instances of genetic disorders in current or previous family members. The geneticist will gather information into a family tree type diagram, indicating genetic disorders from one generation to the next.
Both PGD and PGS testing carry a small risk of harming the embryo(s) during the test or the required freezing process. Genetic testing is currently unable to screen for all known genetic conditions, so there is no guarantee that a tested embryo will lead to a healthy baby. There is a small risk of PGD yielding false negative results, which could mean that an affected embryo is transferred to the uterus. As PGD and PGS are both performed as part of the IVF process, patients would also be susceptible to the risks involved in IVF. However, studies show that embryos biopsied for PGD or PGS do not have an increased health risk compared with IVF embryos that are not genetically tested before implantation.
Counseling before PGD is recommended, as it involves complex issues that affect people differently. For example, children born from embryos with an inherited genetic disorder may not ever develop the disorder, which can mean that an embryo was destroyed unnecessarily after PGD revealed a genetic defect. A woman with the BRAC 1 or BRAC 2 mutation predisposing herself and her offspring to breast and ovarian cancer can benefit from discussing this issue with a genetic counselor, who can guide her in the decision whether or not to destroy an affected embryo.
Plan Your Procedure
- Recovery Time
- Average Procedure Time
- 2 Hours
- Post-op Follow-up
- 10 Days
- Procedure Recovery Location
We Find Answers
If you would like to learn more about PGD at one of our Dallas, McKinney, or Frisco, TX locations, we recommend making an appointment with one of our board-certified reproductive endocrinologists or geneticist at FIRM. We also offer counseling services for patients going through infertility treatments if you would like to discuss PGD with a counselor. Our dedicated team is here to help you make the right decision. Call and schedule an appointment.