Photos courtesy of Genetic Digest
Understanding Consumer Based Genetic Testing
What is direct to consumer testing?
Direct-to-consumer genetic testing is a genetic test that is marketed to the public and patient/consumer guided. In the past, medical genetic tests were exclusively performed at the direction of a healthcare provider if they were concerned about inherited genetic disorders. Direct-to-consumer testing is available to the general public without a healthcare providers’ order and gives individuals access to their genetic information without involving their healthcare provider or insurance company.
What testing companies offer direct-to-consumer testing?
There are many companies that now offer this type of testing. Three of the larger testing companies are:
Ancestry - report on ethnicity, migration trends, and family tree
Looks at other features such as traits, carrier status of recessive genetic disorders and health predispositions
Health predispositions (approved by FDA 2017)assesses for genetic variants that can be associated with a few genetic disorders including alzheimers, type 2 diabetes, celiac disease, hemochromatosis, hypercholesterolemia, macular degeneration, and parkinsons. This type of testing is looking at spot mutations. It does not sequence the entire gene of interest but looks at a single site locations that have been identified as linked to certain health conditions.
No access to genetic counselors
Ancestry - report on ethnicity, migration trends, and family tree
AncestryHealth (not approved by FDA)
Limited access to genetic counselors
Offers patient directed testing for genetic categories including proactive health screen for hereditary cancer syndrome and cardiac disease as well as diagnostic studies for many health related conditions including hereditary cancer syndromes
Full sequencing of genes looking at all sites/locations on the genes for variants linked to hereditary cancer syndromes and other health condition
Genetic counseling is available for the proactive health screens
Genetic counseling is required for the diagnostics tests and ifs offered through the testing company. This includes a consultation prior to testing and a discussion of results after the report has been received.
This is a very good option or direct-to-consumer genetic testing for hereditary cancer syndromes. Good science and good support for interpreting results.
Cost $250 (at the time of writing this article) for the genetic testing and an extra fee for genetic counseling services.
Analysis of genes associated with hereditary cancer risk for breast, ovarian, uterine, colon, melanoma, pancreatic, stomach, and prostate cancers.
Full sequence of genes looking at all sites/locations on the genes for variants linked to hereditary cancer syndromes.
Genetic counselor available to review results and recommendations based on testing results.
Can integrate with your healthcare provider
This is a very good option for direct-to-consumer genetic testing for hereditary cancer syndromes. Good science and good support for interpreting results.
Cost $250 (at the time of writing this article)
Concerns with direct-to-consumer testing when looking at inherited health conditions including hereditary cancer syndromes:
The genes that 23andMe assess for that are linked to Hereditary Breast and Ovarian Cancer Syndrome are BRCA1/2.
BRCA1/2: only looks at 3 sites that are most common in Ashkenazi jewish population
23andMe test detects only 3 out of more than 1,000 known mutations in BRCA1/2 genes that can be associated with an increased risk of hereditary breast and ovarian cancer. It also does not look at other genes associated with breast and ovarian cancer.
AncestryHealth looks at more sites on BRCA1/2 but is not fully comprehensive. It does not look at all genes associated with breast cancer and gynecological cancers.
23andMe also looks at one gene associated with polyposis syndrome and increased risk of colon cancer MUTYH. This test only assesses for 2 variants and does not look at other genes associated with colon cancer.
AncestryHealth does look at all 5 genes associated with Lynch Syndrome that has an elevated risk of colon cancer among other cancers. It once again only looks at a few variant sites and not the whole gene for all variants. It does not look at all genes associated with colon cancer although is more comprehensive than 23andMe
Very high false negative rate - meaning negative does not mean you do not carry and genetic risk for developing cancer
Very high false positive rate - results should always be confirmed with a clinical or diagnostic test as positive results have not been found to be accurate in many cases.
What should you do when you receive a Direct-to-consumer report?
Consumers who test positive for BRCA genetic mutations on the 23andMe test need to follow up with a genetic specialists to confirm the positive finding with clinical laboratory testing before making clinical decisions based on the test.
A negative test with 23andMe can be misleading. It does not mean you do not carry a genetic predisposition for cancer (or other health conditions tested). As it only looks at a few genes and a few locations on each gene, this does not rule out all genetic mutations associated with a condition including cancer.
There are currently 28+ genes that are linked to breast cancer
There are currently 30+ genes that are linked to colon cancer
There are also other genes associated with other hereditary cancer syndromes that can be tested based on your personal and family history.
Consumers who test negative for the three sites on the BRCA genes with 23andMe but have a personal history of breast cancer or a strong family history of breast, ovarian, pancreatic cancer and are interested in finding out more about their individualized risk should meet with a genetic counselor or medical professional who specializes in genetics to discuss risk and options for genetic testing.
***If you are considering a direct-to-consumer genetic testing, or if you have received results and need further explanation, you should seek consult with a genetic specialist. The results may not provide adequate or complete information about your health risks.
What is a genetic counselor?
An individual that has a masters degree in genetic counseling. They work with the healthcare team providing risk assessment, education and support for individuals and families at risk for, or diagnosed with, a variety of inherited conditions. They help individuals understand their genetic test results and how that can impact their care. They counsel on the medical, psychological and familial implications of inherited conditions.
What does a visit with a genetic counselor entail?
They take a detailed personal and family history
Explain what genetic testing is, why it may be recommended, and the potential psychological and familial implications of genetic testing.
They counsel on potential genetic testing options and guide you on what to consider for testing based on your personal and family history
They perform post test counseling so you understand the result of the test.
This information is also passed onto your healthcare team to help direct your care