At-Home Genetic Testing

What are at-home genetic tests?

At-home genetic testing, also known as direct-to-consumer (DTC) genetic testing, refers to genetic tests marketed directly to customers that can be purchased online or in stores. Customers send their DNA sample directly to the company and often receive their results online, without involving a healthcare professional.

Traditionally, genetic testing has been coordinated with the assistance of a physician, genetic counselor, or other healthcare provider. When a provider orders testing and there is a medical indication, insurance may cover part or all of the cost. When a physician or genetic counselor orders testing, evaluation of a patient’s personal and family medical history is an important part of determining which test to order.

Limitations of at-home genetic testing

While at-home genetic tests can be informative, relatively inexpensive, and may even prompt positive lifestyle changes, they are usually not considered diagnostic tests and should not be used to make any medical decisions. The quality and accuracy of at-home genetic testing may vary. Often, the testing done by these companies is quite limited, which is what helps to make the tests so affordable.

How is diagnostic lab testing different from an at-home test?

A diagnostic laboratory will usually look carefully at the entire sequence of letters in a gene or genes of interest. With at-home genetic testing, a laboratory is often only looking at certain regions of certain genes — like a snapshot of a few locations of interest rather than a thorough look at one or more genes.

For example, there are more than 2,000 genetic variants in BRCA1 and BRCA2 that are known to impact gene function and contribute to increased risk for breast and ovarian cancer. 23andMe only tests for three of these variants. If you have Ashkenazi Jewish ancestry, this test may be valuable for you — these three variants are carried by approximately 1 in 40 individuals of Ashkenazi Jewish ancestry. But 23andMe does not look for or report any of the other thousands of changes in the BRCA genes. If you do not have Ashkenazi Jewish ancestry, a negative 23andMe result for BRCA tells you very little.

Beyond the BRCA genes, there are also many other genes associated with increased risk for breast and other cancers that would often be included on a hereditary cancer panel ordered by a genetic counselor through a medical-grade diagnostic laboratory.

What about raw data?

Many at-home testing laboratories allow consumers to download their raw genetic information — much more extensive than what appears on the test report. This data is called “raw” because it has not been validated. The laboratory has not invested time in looking through it to identify false positives or false negatives, both of which are common in genetic testing.

Raw data can be uploaded to third-party services for filtering, which introduces another opportunity for error. One small study suggested that 40% of “positive results” obtained from raw data in this manner are false positives. For people who do have a medical reason for genetic testing, a much better starting point is a higher quality test that includes more thorough analysis of genes of interest and more careful interpretation of any genetic changes found.

Other considerations

Family surprises

Ancestry and genealogy testing is one of the most popular categories of at-home genetic testing. Consumers should be aware of the possibility of receiving unexpected information about family relationships — including misattributed parentage or unexpected close relatives. These “family surprises” can have a significant impact on personal identity and mental health. Grey Genetics has genetic counselors who are specialized in at-home genetic test counseling, including support for unexpected family relationship discoveries.

Data security

After results are returned, what happens to the data extracted from your DNA? Most at-home testing companies have privacy policies in place but cannot guarantee total privacy and genomic data security in the event of hacking. Additionally, attention has been given to the possibility of law enforcement access to genomic databases. The rapid advancements in genetics have outpaced ethical and legislative discussions regarding appropriate use and protection of personal genomic data.

I took a test and have questions. Now what?

If you have questions about your raw data, your 23andMe or other DTC results, or simply want to understand what your family history means for your health, a genetic counselor can help. Grey Genetics offers consultations specifically for people navigating at-home genetic test results.