Types of Genetic Tests
The BRCA1 and BRCA2 gene mutations can pass through families and increase the risk of breast cancer, ovarian cancer, and other types of cancer. Most people who get genetic testing for hereditary breast cancer can expect to have tests that look for cancer-related mutations in these genes.
A mutation is a variation in the DNA that disrupts the function of a gene. Some people refer to mutations as abnormalities.
Additional inherited genetic mutations in the PALB2 and PTEN genes can increase the risk of breast cancer and other types of cancer. While mutations in PALB2, PTEN, and other genes are less common than BRCA mutations, in some cases it makes sense to test for some or even all of them.
Here are a few different types of genetic tests:
Some tests look for a mutation in a specific area of one gene.
Some tests analyze one entire gene for the presence of mutations.
Panel tests look at multiple genes for mutations. These tests can include two genes, five to six genes, 25 to 30 genes, or even more. Sometimes panel tests are called “next-generation gene sequencing” tests because they use the latest technology to sequence many genes at once. Many of these tests look at BRCA1 and BRCA2 mutations along with one or more of the other inherited mutations in genes more recently linked to breast cancer risk, such as ATM, BRIP1, CDH1, CHEK2, MRE11A, MSH6, NBN, p53, PALB2, PTEN, RAD50, RAD51C, STK11, or TP53. Some of the largest panel tests even look at genes that are associated with inherited risk for other cancers besides breast cancer. In addition, there are tests designed for people of different ethnic backgrounds.
Which type of genetic test should you get?
Every person’s genetic cancer risk is unique. A genetic counselor can help you decide which genetic test is right for you.
If someone in your family has tested positive for a mutation in one area of a specific gene, then you can expect to be tested for that same mutation. Your genetic counselor can order a test that looks for the very same area of abnormality a relative has tested positive for and is, therefore, linked to the breast cancer in your family. If a relative has tested positive for mutations affecting different locations in the same gene, testing would look at all those areas.
“A mutation is essentially an ‘address’ that tells you exactly where in the gene that mutation lies,” explains Cristina Nixon, MS, LCGC, a licensed certified genetic counselor with the Cancer Risk Assessment and Genetics Program at Main Line Health in Pennsylvania. “For example, a mutation in BRCA2 such as 5073dupA: the combination of numbers and letters tells the testing lab precisely where to look. If your relatives have this mutation, this is what your genetic counselor would put on the order form.”
In some cases, a person may need to get tested for more than one mutation. Someone with a history of cancer on both sides of their family may consider a panel test to see if it finds additional genetic mutations. Also, some health insurance plans only cover genetic testing once in your lifetime (“one and done”). If cost is an issue and you’re concerned about the possibility of other cancer-related genetic mutations, then you may want to see if your health plan covers panel testing.
If a breast cancer-related mutation hasn’t yet been identified in your family, your genetic counselor can help you decide which genetic tests make sense for you. At minimum, most people get tested for BRCA1 and BRCA2 mutations. “With some labs, you can add in testing for other genes that are considered high-risk, such as PALB2, p53, and PTEN, among others,” explains Cristina Nixon. “However, you sometimes can expand it further to include moderate-risk gene mutations, and then maybe expand it even further to include those where we don’t know as much about what the risks from mutations are. They’re relatively new, so the trouble with adding them in is that sometimes we don’t know what to do when there’s a mutation found in one of those genes. These are all important factors to consider.”
Additional considerations to take into account when deciding how many genes to get tested for include the following:
The pattern of cancers in your family, including any relatives who have received treatment for cancer, as well as the types of cancer and their ages when they were diagnosed. If the pattern suggests a BRCA1 or BRCA2 mutation, it makes sense to start with those two genes. Your genetic counselor may recommend additional tests for other gene mutations if other types of cancer run in your family. Your counselor also may recommend additional tests if your family history is incomplete or unknown, whether it’s because of missing medical records, a parent who has passed away, or a closed adoption.
Determine what you do or don’t want to know about your cancer risk. Genetic mutations that increase breast cancer risk also increase risk for other types of cancer. You may not want to know if you test positive for cancer-related gene mutations if there are no published guidelines yet on how to reduce cancer risk. If this is the case, then a panel test that includes many genes may not be right for you.
Health insurance coverage. Some health plans don’t cover panel testing for multiple genes unless there is strong evidence you’re at risk of having a mutation in more than one gene, or there are clear action steps you can take to reduce risk if you test positive. Some insurance plans also might only cover genetic testing once in your lifetime, so it’s important to consider your options carefully.
The testing company your hospital uses or that your health insurance considers in-network. Myriad Genetic Laboratories, GeneDx, Ambry Genetics, and LabCorp are just some of the many laboratories that offer genetic testing. Some laboratories let you choose which genes you want to include in a panel test. Other laboratories only offer pre-set panels because certain genes have to be tested as a group. If your health insurance coverage limits your choice of laboratory, it may affect your choice of genetic test.
Past genetic test results. If you and your relatives have tested negative for a BRCA mutation in the past, but have a strong family history of breast cancer or other cancers, you may consider panel testing to see if another genetic mutation might be the cause. It’s important to note that if you tested negative for a BRCA1 or BRCA2 mutation before 2006, you may want to consider getting tested again since the technology has improved. Tests can now detect mutations involving a larger area of each gene, including large deletions, duplications, or rearrangements. Before 2006, tests could only look for smaller gene mutations.
Genetic tests you can purchase on your own
If you’re interested in getting a genetic test, you have the option of purchasing an at-home genetic test or DNA test. Some companies, such as Veritas Genetics and Color Genomics, offer kits for at-home testing of BRCA1, BRCA2, and other genes. Veritas Genetics and Color Genomics require your doctor to approve the test. If you don’t have a doctor, both companies can connect you with a doctor who can review your case and order the test. Both companies also can connect you with a genetic counselor if you need one.
The company 23andMe offers the Personal Genome Service Genetic Health Risk Report for BRCA1/BRCA2 (Selected Variants). The company doesn’t require your doctor to order the test — you can purchase the test directly from 23and Me. It’s important to note that the test only detects three out of more than 1,000 known BRCA mutations, and the company does not connect you with a genetic counselor.
The main advantage of at-home genetic tests are convenience and cost. At-home genetic tests tend to be less expensive than hospital-ordered tests, costing between $200 and $300. Still, there can be some major disadvantages:
Some of these genetic tests may only look for mutations in the BRCA1 and BRCA2 genes. The tests don’t necessarily include other genetic mutations linked to breast cancer and ovarian cancer, including PALB2, CHEK2, and PTEN.
If you use your health insurance coverage for a test that only looks for BRCA1 and BRCA2 mutations, you may not be covered for additional tests that look at a broader range of genes in the future.
Companies that sell at-home genetic tests don’t typically connect you with a genetic counselor. A genetic counselor can help you decide which genetic test is right for you and offer on-going, in-depth information.
“Whatever option you choose, it’s important to understand what mutations are included in the test and what the results might mean,” says genetic counselor Cristina Nixon. “The main caution is to be aware of what you’re being tested for ahead of time. Don’t just do the test, but actually talk to somebody about what this test has included and what the results might mean. You need to be aware of what the implications are should one of the genes come back positive [for a mutation].”
— Last updated on July 27, 2022, 1:46 PM