Genetic Counseling When You're Trying to Conceive
We each have a unique genetic profile that makes us who we are. With every new child, the genetic dice is thrown to decide which genes the baby will inherit from both mother and father. An important question then is which of those genes have the potential to harm your baby?
Along with your brown eyes and your partner’s dimples, your baby might inherit some genes with genetic misspellings (gene variants) that can cause medical conditions. And while most of these anomalies are harmless, two copies of a harmful variant could be detrimental.
Couples trying to conceive have the tools to identify potential inherited genetic conditions before conception. With genetic tests and genetic counseling, parents now can choose whether to use in vitro fertilization (IVF) in conjunction with preimplantation genetic testing for monogenic diseases (PGT-M, previously known as PGD) to select embryos that do not have risks of inheriting specific harmful conditions or use prenatal testing to prepare for a baby that will have special health needs.
Should I be tested?
While you’re trying to conceive, consider scheduling a preconception genetic counseling meeting. Your doctor will review your family history, and your partner's, for birth defects, chromosomal disorders (e.g., Trisomy 21), known inherited disorders, cancer or mental health issues. A history of two or more pregnancy losses, stillbirth, or infant death may also suggest an underlying genetic cause.
Your doctor may order genetic testing for you and your partner to find out whether you carry genetic variations for some of the most common genetic disorders. There is a wide range of options for genetic testing, allowing you to screen for targeted common genetic disorders or several hundred genetic disorders, including ones that are uncommon. Your doctor or genetic counselors can review your genetic blood test results with you to explain your personal risk of passing on troublesome genes to your child.
If you are using a targeted approach to genetic screening where you and your partner test for just the most common genetic inherited conditions, your doctor may also ask you about your ethnic background because some genetic variations are more common in some ethnic groups compared to others.
People with Southeast Asian background are more likely to carry the genetic variations for inherited blood disorders such as hemoglobin E¹. Those with European (Caucasian/white) ancestry, are at greater risk of being carriers of the cystic fibrosis² gene. If either you or your partner have African (Black) background, you are more likely to carry sickle cell gene variants that cause sickle cell disease³. If both you and your partner have any Eastern European Jewish (Ashkenazi Jewish) ancestry, you are at increased risk of passing on a number of genetic diseases including Tay-Sachs disease⁴, Canavan Disease⁵ and familial dysautonomia⁶.
The targeted approach is not as effective and efficient in many situations. If you and your partner have different ethnicities, there are more variants to test.
What are some other tests to consider?
If you’re considering IVF, your doctor may recommend a preimplantation genetic testing for aneuploidy (PGT-A). This test is done before the embryo transfer to determine which embryo(s) have cells with a normal number of chromosomes, or have the best chance of implanting in the uterus. An euploid embryo has cells with a normal number of chromosomes (46), and cells in an aneuploid embryo have an abnormal number.
If you are already pregnant and have concerns about your family history, then a prenatal genetic counselor can help you determine if it is right for you to have a genetic screening for a specific genetic trait or general chromosomal abnormalities. You can choose from a variety of non-invasive prenatal genetic screening tests, as well as more definitive testing through amniocentesis⁷, where a sample of amniotic fluid is drawn from the amniotic sac around the fetus, usually at 16 to 22 weeks of pregnancy, for testing.
If you have specific concerns about your family history, genetic counseling can help you distinguish conditions that can be passed on through family genetics from those that aren’t inherited genetically. Knowing the actual risk of having certain inheritable conditions can help you better prepare for your family’s health.
1: National Center for Advancing Translational Sciences. Hemoglobin E disease. rarediseases.info.nih.gov/diseases/2641/hemoglobin-e-disease
2: U.S. National Library of Medicine. Cystic fibrosis. ghr.nlm.nih.gov/condition/cystic-fibrosis
3: National Heart, Lung, Blood Institute. Sickle cell disease. https://www.nhlbi.nih.gov/health-topics/sickle-cell-disease
4: U.S. National Library of Medicine. Tay-Sachs disease. ghr.nlm.nih.gov/condition/tay-sachs-disease
5: U.S. National Library of Medicine. Canavan disease. ghr.nlm.nih.gov/condition/canavan-disease
6: U.S. National Library of Medicine. Familial dysautonomia. ghr.nlm.nih.gov/condition/familial-dysautonomia
7: March of Dimes. Amniocentesis. www.marchofdimes.org/pregnancy/amniocentesis.aspx
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