Testing for Family Members
Cascade Testing
If you have learned that you carry a hereditary genetic variant, your family members may have the opportunity for targeted, informative testing. Positive or negative, the answers that follow can be genuinely life-changing.
How Genetic Variants Run in Families
We each inherit half of our genetic makeup from each parent. None of us gets to choose what's in that mix and only rarely do we have any control over what we pass down.
Family history of many different health conditions is often polygenic, meaning that a number of different genes may contribute small increases in risk. Genetic testing related to polygenic testing is still in its infancy. Historically, clinical genetic testing has focused on variants in single genes that are associated with significant increases in risk. (Hence the sloppy phrase 'The gene for ____.') Every one of us carries genetic variants. Some of these have medical significance; many do not.
When a variant known to be associated with a specific single gene condition is identified in an individual, this opens up the possibility of cascade testing: targeted testing of family members for the identified familial variant.
Illustration of cascade testing. Squares represent biological males; circles represent biological females. Each child of a carrier has a 50% chance of inheriting the variant; grandchildren of a carrier have a 25% chance.
What cascade testing is — and why it matters
When an individual shares a positive test result with family members, they are giving their family members the option of pursuing targeted testing specifically for that variant. Often, this approach is more informative and more cost-effective than general screening.
→ Those who test positive are known to have, to be at risk for, or to be carriers for the related condition. In many cases, there are medical management changes that may be recommended to reduce or better manage risks.
→ Those who test negative are considered "true negatives." They are generally considered to be at population risk for the disease in question — in spite of their related history.
Exactly what positive and negative results mean in these scenarios depends on the disease, the gene, and sometimes on the specifics of someone's personal and family health history.
What is needed to make cascade testing possible
For cascade testing to be possible, a laboratory needs to know the specific variant identified in the family member who was tested first. "I tested positive for the breast cancer gene" does not make it clear which gene was found to have a significant variant. Even saying "I tested positive for a variant in the BRCA1 gene" isn't clear. It's a bit like telling someone you live in Ohio — and that they're welcome to come by any time… but not providing them with your actual address. The genetic testing report from the laboratory will include specific language that tells another laboratory exactly what was found where — as well as how the first laboratory interpreted that finding and why. It's a bit like a GPS location.
Genetic test results belong to the individual who was tested. Sometimes, people choose not to share results with family members. Other times, people are open to sharing results but are not sure how to broach the topic. Both cases are often helpful to talk through in genetic counseling. Often, however, genetic counselors hear stories of families that are willing and wanting to share results with family members — they just can't find the piece of paper with the results…
Who in the family should be tested first?
The ideal starting point is to test the family member most likely to carry a significant genetic variant. This is usually someone who has a related diagnosis. When testing someone without a diagnosis, it's harder to interpret a negative result. But we don't live in an ideal world. Families are complicated. "Ideal candidates for testing" are not always living or available for testing. When the picture isn't straightforward, a genetic counselor can help interpret what a negative result in an unaffected relative means.
This is also part of what makes a positive result in a family so valuable: it opens a door that isn't otherwise available. Not everyone has access to that kind of clarity — and for families navigating uncertainty without a known variant to test for, genetic counseling can help make sense of what the picture does and doesn't tell us.
Getting genetic testing ordered
Genetic testing can be ordered in several ways:
- Through their own primary care provider; some may order genetic testing as a routine part of their practice
- Through a local genetic counselor; some physicians routinely refer patients to genetic counseling
- Through a genetic counselor available through telehealth. findageneticcounselor.com is a searchable directory of genetic counselors available both in-person and via telehealth
- Through Grey Genetics, which can also facilitate test orders in all 50 states and D.C.
When professional guidelines support testing, the cost of genetic testing is often covered by insurance. For those without coverage, high-quality testing is generally available out-of-pocket at a cost accessible to many people. Financial hardship programs are available through many testing laboratories. A genetic counselor can help navigate these options.
A genetic counseling appointment covers whether testing makes sense, what to order, and the range of possible results. Genetic counseling is often an ideal starting point before testing is ordered, but the best route to testing can depend on many individual considerations. Some physicians will order genetic testing for patients and then refer to genetic counseling, depending on the results of testing.
How Grey Genetics can help
If you haven't reviewed your own results with a genetic counselor yet
Understanding your own results is usually the best foundation for these conversations. If you've had genetic testing and have a result you haven't yet discussed with a genetic counselor, that's a good place to start before sharing it with family. Schedule an appointment to go over what your result means before deciding how and when to tell relatives.
If you want to arrange a genetic counseling appointment for a family member
You can prepay for a genetic counseling appointment on behalf of a family member. Then let them handle the scheduling when they're ready.
Voucher applicable toward any genetics consult. Buying for more than one relative — say, two kids in college? Increase the quantity in your cart. Each family member will self-schedule and complete their own consent forms before their appointment.
If You're Hoping a Family Member Will Get Tested
Two one-page guides for the person waiting on someone else to test first.
Cascade testing depends on someone in the family agreeing to test — often the relative who's already affected. If that hasn't happened yet in your family, these two guides may help, depending on how your family tends to talk things through: one is for you, to help start the conversation directly; the other is for a relative who'd rather read something on their own first, before talking it through.
Talking With Your Family About Genetic Testing
A guide for you: how to bring it up, respond to common concerns, and what to say if the first conversation doesn't go far.
Download PDF
If Someone in Your Family Has Asked You to Consider Genetic Testing
Written for your relative, not you. Some people do better with something to read and sit with on their own first — this one is meant to be printed and handed over, not just linked.
Download PDF