Licensed Genetic Counselor Elizabeth Kearney, MS, CGC, MBA, from Mainstream Genomics gives her expert opinion on what genetic testing is, how it can be useful and what the other options are.
The decision to undergo egg freezing or in vitro fertilization (IVF) is not one people often take lightly. Considering the investment in time, money, and mixed emotions, a growing number of people are doing genetic testing.
Most babies are born healthy, but about 3-5% have a birth defect or problem with development. Some of those problems happen by chance, and some can be inherited. Before egg freezing or IVF, some people want to know how high their chances are of having a baby with a birth defect or developmental issue. This assessment can be done through family health screening, genetic testing, and/or genetic counseling. By having this information early on, people are able to access the growing number of treatments for inherited disease, they're able to expand options for family planning, and they can improve the management of pregnancy or neonatal care.
What is genetic testing and why does it matter for egg freezing and IVF?
Genetic testing, also known as DNA testing, can be a little scary. Images of a test kit arriving in the mail may even turn people off. However, with the right guidance and support, genetic testing can be a valuable tool whether people are ready to have a baby right now or might want to in the future.
Genetic testing examines a person’s DNA through a blood or saliva sample. DNA is like a blueprint for how a body grows, develops and functions. There are segments of the DNA that are called genes. Each gene plays an important role in the body. A typical person has two copies of most genes, one inherited from the mother and one from the father.
Some people have some differences (called variants) in the DNA that cause genes to not work properly, resulting in genetic disease. Genetic testing allows us to analyze a person’s DNA to look for these differences.
However, the DNA testing available today cannot tell you everything about a person’s genetic background. At this time, the science behind DNA is still developing. There isn’t one single genetic test that can give all the information about a future baby’s health. Therefore, a good place to start is by collecting a family health history. An initial screening conducted by a genomics professional offers an important first step in understanding exactly which genetic tests might be most informative.
Start by getting a family health history from a genetic counselor
Collecting family health history involves asking questions about a person’s health and their family. Most people have family members with different health issues, some of which can be inherited. Most of these inherited genetic conditions are not detectable by standard genetic testing done by fertility clinics or prenatal care. For example, if a parent-to-be has a family member with a childhood condition, such as a birth defect or severe learning problem, he or she could have a higher chance of passing something similar to a child. In the case of IVF, collecting detailed family history on both parents before or early in the IVF process can better inform couples regarding the chances for an inherited condition in a future child.
Collecting detailed family health history can help couples decide which of the over 150,000 genetic tests available today are best for them. (1)
While this can seem daunting, genetic counselors are medical professionals trained specifically in evaluating family health history and helping the patient decide which genetic testing is going to be best suited to their needs. It's important to note that genetic counseling is not the same thing as genetic testing. Genetic counseling is a conversation between two people. It is not genetic testing itself.
A genetic counselor will integrate the family and health information, genetic testing results, and equally important, the parents-to-be’s values and goals, into one complete picture. Genetic care for one person or couple will not be the same as it is for another. With so many tests on the market, and so much at stake, a genetic counselor offers a strategic and personalized approach.
When and how can genetic tests be used?
The most likely outcome for any pregnancy is a healthy child. However, if genetic testing shows that a person or couple carries a higher chance for an inherited condition in a child, this may help choose among the various paths to parenthood.
Genetic counseling/testing for egg freezing
It can be helpful to receive some genetic counseling prior to egg freezing in order to understand if there is a higher chance to pass on inherited conditions. However, if the sperm donor is unknown at the time of freezing, it will be important that the donor provide family health history and that genetic testing is considered for the sperm donor, too,. The good news about undergoing any sort of fertility treatment is that there is an opportunity to learn about genetic conditions before a pregnancy occurs. We'll go into the various genetic tests available before egg freezing in detail.
PGT: Genetic testing of embryos through IVF
In vitro fertilization (IVF) is the process in which people use fresh or frozen embryos to try to get pregnant. Special genetic testing, called preimplantation genetic testing (PGT), allows testing of embryos before they are transferred to the uterus during the IVF process. For example, if a DNA finding in the family is known ahead of time to cause an increased chance for a baby with a specific genetic disorder, genetic testing for this disorder can be done on the embryo.
During the process of PGT, the IVF center takes a small number of cells from the outer layer of an embryo after five days of development. A special genetic testing lab can perform genetic testing on this small number of cells from the embryos to look for the non-working gene or genes that cause disease. The IVF center will then transfer only the embryos without the disease into the uterus.
Although this additional genetic testing adds some costs, it may be preferable to testing a pregnancy. Testing a pregnancy can carry ethical dilemmas for the parents if a problem is found and they have to decide whether to continue the pregnancy.
Many people feel more comfortable testing an embryo and only transferring embryos that are not affected by the inherited condition.
Although testing embryos during IVF is available to anyone, it might not be discussed unless the patient has genetic testing conducted ahead of time to find out if she carries any genes for inherited disease. Genetic testing before freezing eggs will ensure this option is available, too, without the pressure of the IVF cycle deadline.
CVS & Amniocentesis: Testing a pregnancy
Even though it is possible to use IVF and genetic testing on embryos prior to implantation, some people choose to wait until pregnancy to have genetic testing conducted on the fetus. Special medical procedures called chorionic villus sampling (CVS), done in the late first trimester, or amniocentesis, done in the second trimester, allow genetic testing to show whether a child has an inherited disorder that is known in the family.
During CVS, a catheter is inserted through a woman’s cervix to obtain a small amount of tissue from the placenta. With amniocentesis, a thin needle is inserted through the woman’s abdominal wall and uterine wall to obtain a small amount of the fluid around the baby. (With CVS and amniocentesis, there is no need to touch the developing baby because the tissue or fluid contain cells, which have DNA.) A laboratory uses the tissue or fluid to look at the baby’s DNA.
If the results of genetic testing though CVS or amniocentesis show that the fetus has an inherited disorder, the person will need to decide whether to continue the pregnancy. If they do, the advance information can help manage their pregnancy and delivery plans. For example, some inherited diseases require medical intervention right away at birth, so it can be smart to deliver at a special medical center.
Knowing in advance that the child has an inherited disorder may improve treatment for that child and in some cases, even allow access to drug treatments or surgeries.
Although prenatal testing is available to all pregnant women, some prenatal care providers may not offer this option unless they know there is an increased risk of a genetic disorder. Pregnancy is a sensitive time and it can be helpful to consider options in advance. Genetic testing before egg freezing and IVF will ensure that most options are available without the pressure and anxiety of pregnancy.
What other options do I have if I know I have an inherited disorder but wouldn't want to test a pregnancy or test embryos?
Use an egg donor
Some people who know they carry DNA findings responsible for serious inherited disorders do not want to pursue genetic testing on embryos or during pregnancy. They still have options. Some may decide to go through IVF anyway but use an egg donor. Many IVF centers work with egg donor agencies and can help individuals or couples find a suitable egg donor. However, without genetic testing before freezing eggs, some people may never realize that using an egg donor is the right path for them. Even if genetic testing is offered later, which is not certain, they would have invested in freezing eggs but will not use them.
Adopt
Understandably, many people want to have a child that is genetically their own. But every person's journey is unique, and some people change their minds about adoption. Perhaps they realize that the experience of parenthood, not a genetic relationship with a child, is what they seek. In that case, freezing eggs may not be the best path. When considering the benefits of freezing eggs and IVF against the benefits of adoption, genetic testing could be an important deciding factor.
Decide not to have children
Many, many people long to be parents as part of the fundamental human experience. Services like egg freezing, IVF, and other fertility treatments have opened many paths to parenthood that didn’t exist in the past. However, as stated above, the path to parenthood is unique for everyone. Some people find others ways to direct their parental instincts. Channeling energy into causes that support children or into other family members, like nieces and nephews, can be very satisfying.
Which genetic tests would I consider before egg freezing?
There are over 150,000 different genetic tests available today, so it can be confusing for women or even physicians to know what tests are right for them. Here are some standard genetic tests that have a role in pregnancy planning:
Carrier testing
As mentioned above, there are some standard genetic tests that prenatal care providers and IVF clinics often offer patients. Carrier testing is an example. Carriers for certain inherited conditions are usually healthy, but they have a non-working copy of a particular gene. In most cases, also having a working copy of the gene keeps a carrier from having the disease. If a child receives only non-working copies of a particular gene from their parents, the child will likely have the disorder or disease. Therefore, before someone invests in egg freezing, they may want to undergo carrier testing, and their partner may want to, too.
Many people start with carrier testing for themselves, and they only ask their partner to have carrier testing if the results show that they are a carrier for an inherited condition. Other couples decide to test at the same time. Laboratories that offer carrier testing make it easy by sending people test kits through the mail to collect a saliva sample or helping to arrange a blood draw close to home.
However, it is important to be careful to choose a test that meets at least the minimum guidelines set by expert medical societies. As described above, a genetic counselor can help you choose the right test. As stated above, standard carrier tests do not detect all inherited conditions, so careful review of family health history is still important.
Specialized genetic tests for specific conditions in the family
The number of inherited diseases on carrier screening tests vary depending on the laboratory performing the testing. However, regardless of the number of conditions, there are still many inherited diseases not included in any carrier screening. If there is a known inherited condition in the family, it may be possible for parents-to-be to pass that on to their child, too, even if they are healthy at the time of egg freezing or IVF.
Reviewing family health history can assess whether a different type of genetic test or medical screen may be needed in addition to carrier screening. Genetic testing may be possible to better understand the chances for the baby. Again, a genetic counselor can review family health history to determine whether any special genetic testing might be helpful.
Genetic testing for adult-onset conditions
A very new form of genetic testing will allow a healthy person to test for some inherited conditions of adulthood. Some of these adult-onset conditions do not show symptoms until after the childbearing years, and the symptoms may vary in severity, too. Although many people have something in their family that might suggest these conditions, not everyone does. The family members with the condition could have very mild symptoms or are too young to show the disease yet. This is also applicable for people that are adopted or know very little about their biological family for other reasons.
An example of an adult-onset inherited condition is hereditary breast and ovarian cancer. (2) About 5-10% of breast and ovarian cancer is hereditary. Some people have seen news stories about BRCA1 and BRCA2, two genes known to explain a large portion of hereditary breast and ovarian cancer. People with this hereditary form of cancer have a higher chance of breast, ovarian, pancreatic, prostate, and skin cancer. (The type of skin cancer in this condition is melanoma.) There are other genes that play a role in hereditary breast cancer though, so many labs offer tests that include a variety of genes. Families with a hereditary form of cancer tend to see cancer at a younger age and in a larger number of relatives. A genetic counselor can help determine whether a person’s family health history suggests an inherited form of cancer.
How to get started with genetic testing before egg freezing
People may assume that their fertility clinic or prenatal care provider can help them get started with genetic testing before freezing their eggs. However, it can be hard for busy physicians or nurse practitioners to keep up with the advances in genetic testing. Most will ask some basic family health questions and will offer some standard genetic testing. However, studies show that about 10% of couples have a genetic risk to their baby that routine prenatal care did not identify. (3)
Therefore, to get started, women who are considering freezing their eggs may want to seek services from a genetic counselor who will ask deep and broad questions about the health of family members, like siblings, nieces, nephews, aunts, uncles, and grandparents. Only then can people be sure they will be offered more than just the standard screening offered to everyone, including any specialized genetic testing that is right for them.
Genetic testing can be a helpful first step in deciding whether to freeze eggs or IVF and protect the health of a future family. It doesn’t have to be scary if combined with the guidance of genetics experts to explain each step along the way.
Guest Expert
Elizabeth Kearney, MS, CGC, MBA
Licensed Genetic Counselor
Elizabeth is passionate about supporting patients and providers throughout the fertility patient journey in genomics.
Sources:
A Coding Solution for Genetic Testing. Concert Genetics White Paper, June 2020. Accessed 11/3/2020 https://www.concertgenetics.com/resources/a-coding-solution-for-genetic-testing-v1-1/
Hereditary Breast and Ovarian Cancer. Cancer.net, American Society of Clinical Oncology, May, 2019. Accessed 11/3/2020 https://www.cancer.net/cancer-types/hereditary-breast-and-ovarian-cancer
Meschede, SD and Horst, J. The practical importance of pedigree analysis in women considering invasive prenatal diagnosis for advanced maternal age or serum screening. Prenatal Diagnosis 2000.
Comments