On that note, I recently had the pleasure to connect with Shivani Nazareth, MS CGC, Director of Medical Affairs at Counsyl, a DNA testing and genetic counseling service. For more than 15 years, Shivani has worked with thousands of couples to help them understand how genetic screening can help them make informed decisions when building a family.
Can you talk a bit about what carrier screening entails for couples who are pregnant?
Sure! To clarify, it is ideal that carrier screening be performed before conception, rather than during pregnancy, as timing makes a huge difference in allowing couples to utilize the information to their benefit. It is performed on a sample of blood or saliva, from which DNA is analyzed to determine if an individual is a “carrier” of a genetic disease. Carriers are healthy people with an alteration, also known as a mutation, in their DNA. The test includes a wide range of conditions, from hearing loss to chronic or life-threatening illnesses. If a pregnant woman is found to be a carrier, the next step is usually to test her partner’s DNA. This is because both mom and dad would have to be carriers of the same gene (with few exceptions) in order to conceive a baby with the condition. While this may initially seem like unwanted information, the purpose of carrier screening is to identify potential health issues as early as possible, thereby giving couples time to research all options and improve the likelihood of having a healthy child.
What are the main misconceptions that prevent couples from doing carrier screening?
Lack of family history seems to be the most common misconception about carrier screening. In other words, people mistakenly believe that if they have “nothing in the family,” they do not need carrier screening. In reality, most babies (>80%) with rare inherited diseases are born to parents with absolutely no family history of the disease. Rather, there can be many generations of healthy carriers in a family who just never happened to pair up with another carrier. Parents are often surprised by the diagnosis, which is why carrier screening should be considered by all of couples of reproductive age.
Can any couple do carrier screening? Or, do you need a preexisting condition (or a heritage that warrants extra scrutiny – I.e. Ashkanazi Jewish)?
Yes, any couple can do carrier screening and every couple should consider it. While certain inherited diseases are more common in the Ashkenazi Jewish population, this doesn’t mean that they do not exist outside of that population. In fact, nowadays most babies with Tay-Sachs disease, a traditionally “Jewish” disease, are born to parents with no known Jewish ancestry. A study published by Counsyl in JAMA last year showed that expanded carrier screening is more effective than ethnicity-based screening at capturing at-risk couples. Expanded panels, like the Counsyl Foresight Screen, can include over 100 rare but serious diseases. Those who get the information upfront can better manage their risks and consider alternative reproductive options. For example, some pregnant women benefit from additional ultrasounds during pregnancy, fetal cardiac tests, consideration of diagnostic testing, or initiation of early intervention and/or treatment in the newborn period. Sometimes a simple dietary modification can prevent disease onset. For those who obtain the information prior to conception, there is also the option of pursuing fertility treatments and only using embryos that are unaffected. While all of this can seem overwhelming at first, we are fortunate to live in a world where we have access to such great advances in modern medicine— and ultimately some element of control over the outcome of our children’s health.
What are some of the genetic causes for hearing loss that Counsyl tests for?
As you’ve openly discussed, your daughter Sonya inherited GJB2-related DFNB1 nonsyndromic hearing loss. GJB2 encodes the protein connexin 26, which is needed for the proper formation of the cochlea, or the auditory portion of the inner ear. This type of hearing loss is recessively inherited, which means that both parents must be carriers of this gene in order to have a child with hearing loss. As you and Yan know, being a carrier does not impact your own hearing in any way. This is because genes are inherited in pairs, and you each have one copy of the gene without a mutation. Sonya, on the other hand, inherited two mutations—one from you and one from Yan—and therefore was born deaf. There are a few additional genes on our carrier screen panel that are associated with partial or complete hearing loss. They include Usher syndrome and Pendred syndrome. The word “syndrome” indicates that the hearing loss is one of a few different symptoms that are inherited together; for example, children with Usher syndrome have both hearing and vision loss. A full list of diseases included in the Counsyl panel can be found here.
How much does genetic testing typically cost and does it depend on the level of testing? How much is covered by insurance? Do you need a referral from another doctor?
Carrier screening is one of a few different genetic tests offered during pregnancy. It is covered by most health plans. At Counsyl, the test can only be ordered by your doctor, but it doesn’t require a referral to another specialist. Since insurance plans and deductibles vary, Counsyl offers a personalized out-of-pocket cost estimate within 48-hours of your doctor’s order. You can then use this estimate to determine whether you want to move forward. Counsyl also offers options for individuals that do not have or are not covered by insurance. To date, we have screened more than 850,000 patients and worked with more than 17,000 healthcare professionals. We strive to make our genetic screens as affordable as possible, so that anybody who wants the information can access it.
When is it best to speak to a genetic counselor rather an obstetrician, gynecologist or geneticist? What can a genetic counselor help me learn that my doctor cannot?
There are a few situations where it is best to speak with a genetic counselor in addition to your doctor. If you have a personal or family history of a rare disease and want to learn more about whether it can be passed to your children, a genetic counselor can help you understand the inheritance pattern and navigate the pros/cons of pursuing testing. Since even expanded carrier screening panels do not cover all mutations associated with rare diseases, a genetic counselor can also help you choose the right DNA test. When it comes to utilizing genetic information, there are no right or wrong decisions, as every situation is unique and personal. Genetic counselors are up-to-date on advances within the field and can help parents think through every decision path. As you know, some parents with deaf children choose to learn sign language and embed themselves within the deaf community; others do as you did and pursue cochlear implants to enable hearing. Both are valid options— different strokes for different folks. As such, when a couple is found to be at risk of passing on a genetic disease to future children, speaking with a counselor can ensure that they have fully explored every possible intervention and chosen one that is right for them. In this regard, Counsyl makes it easy to access professional guidance. They employ more than 50 board-certified genetic counselors who are available on demand via teleconsult once test results are available.
If my husband and I are both carriers, what are my options to ensure a healthy baby?
Two healthy carriers of the same disease gene have a 1 in 4 chance with each pregnancy of conceiving a child with the disease. There are a few exceptions to this rule, because certain genetic diseases are only inherited from mom to baby. Parents use this information in different ways, based on their personal values, the severity of the disease for which they are carriers and the availability of effective treatment. Some couples choose to conceive naturally and “wait and see,” since the odds are in their favor to conceive a baby without the disease. At 10 weeks of pregnancy, these couples might elect to pursue a chorionic villus sampling (CVS) to determine whether their pregnancy is affected. Having this information upfront equips parents with the information necessary to make the right decision for them. For some it allows them to either better prepare for the birth of a child with a chronic or terminal illness, or it may lead them to the difficult decision of ending the pregnancy. Other couples choose to conceive using a sperm or egg donor who is not a carrier of the same disease, thereby reducing their risks. Finally, some parents choose to adopt children, while others may elect fertility treatments (IVF) and test embryos prior to transfer. Where IVF is used, only unaffected embryos are implanted into mom’s uterus, a procedure known as preimplantation genetic diagnosis (PGD).
Shivani Nazareth is Director of Medical Affairs at Counsyl, a DNA testing and genetic counseling service. She worked as a clinical genetic counselor for over ten years in New York City, most recently at Weill Cornell Medical College. Shivani obtained her graduate degree from the Icahn School of Medicine at Mount Sinai and currently serves on the National Society of Genetic Counselors’ Public Policy Committee.
How has genetic testing changed since you started working in this field? Have new screens been added over time (which ones?) What are some of the most recent advances and most active areas of research?
I’ve been a genetic counselor for nearly two decades, and in that time, the field has advanced tremendously. We used to offer genetic screening for only a handful of diseases, like cystic fibrosis and Tay-Sachs disease, based on a patient’s ethnicity. The tests were ordered gene-by-gene, rather than in panels, and the mutations were pre-specified. This meant that most people did not learn they were carriers of rare diseases until they gave birth to a child with the disease. Today, we can test for hundreds of genes and thousands of mutations at approximately the same cost, if not cheaper, than previously used technologies. This gives parents-to-be many more options. If I were to think of an analogy, it would be akin to the way we listen to music. We used to purchase CDs and have access to only a few pre-selected songs. Today, we can download hundreds of songs in digital format, and the previous modality seems absurd. This shift in the way we access genetic information has allowed researchers to focus on treatments that are specific to a patient’s individual makeup, referred to as personalized medicine. It is an area of active research that has made DNA testing relevant to many common conditions, not just rare diseases. One day, we will balk at the idea that the same medications were used for all patients with a similar diagnosis. Instead, medications will be tailored to a person’s genetic makeup, increasing effectiveness and decreasing side effects. In short, a better understanding of an individual’s DNA will change the way we practice medicine. Counsyl has paved the way within the field of reproductive medicine, giving couples more options than ever before to conceive and sustain healthy families. Your family’s story is a great example of the impact that critical genetic information can have in improving the life of a child. Truthfully, this is the stuff that gets me up and going each morning, so I thank you for being brave enough to share your story with the world.