How Accurate Is 23andMe?

23andMe is one of the most popular direct-to-consumer (DTC) genetic testing services on the market, offering individuals the opportunity to learn more about their ancestry, genetic traits, health predispositions, and even their carrier status for certain inherited conditions.

But how accurate are the results?

In this article, we’ll take a closer look at the accuracy of 23andMe’s genetic testing services.

Also, read How Long Does 23andMe Take?

Overview of 23andMe’s Genetic Testing Process

23andMe’s genetic testing process involves several steps that start from the moment you order a kit and conclude with you receiving your personalized genetic reports.

Here is a closer look at the process:

1. Ordering and Registration

First, you purchase a 23andMe kit either from their official website or a certified retailer.

Once you receive your kit, you register it online on the 23andMe website.

Registration is crucial because it links your sample to your personal account where you’ll receive your results.

2. Sample Collection

The 23andMe kit comes with a saliva collection tube.

You are required to spit into this tube until it reaches the fill line.

The tube contains a stabilization buffer which helps preserve your DNA until it reaches the lab.

After you’ve provided your sample, you seal it back in the collection bag and mail it back to the lab with the prepaid package.

3. Laboratory Analysis

Once your sample reaches the lab, DNA is extracted from your saliva and prepared for analysis.

The analysis is done using a genotyping chip, a technology that identifies hundreds of thousands of specific locations (known as SNPs) in your genome.

23andMe uses the Illumina Global Screening Array (GSA), which looks at over 600,000 SNPs across the genome.

Genotyping does not sequence your entire genome but rather focuses on these specific points of interest, many of which have been associated with particular traits, health conditions, or ancestry information.

4. Computation and Report Generation

After genotyping, the raw data is processed through 23andMe’s algorithms to generate personalized reports.

For ancestry reports, the data is compared to reference data from global populations.

For health-related reports, the presence or absence of certain genetic variants associated with specific conditions is identified.

5. Accessing Your Results

Once your reports are ready, you’ll be notified via email, and you can access them by logging into your 23andMe account.

The results are presented in a user-friendly format, with lots of additional information available to help you understand what your genetic data means.

Throughout this process, it’s important to note that 23andMe takes customer privacy seriously.

They use industry-standard security practices to store your DNA sample, your DNA test results, and other personal data you provide to them.

Section Summary

23andMe’s genetic testing process is a combination of laboratory DNA analysis and sophisticated data computation, all designed to provide you with an individualized glimpse into your ancestry and health predispositions.

How Accurate is 23andMe Ancestry Report?

23andMe’s Ancestry Composition report is one of their most popular offerings.

The company reports over 99.5% precision and recall in a cross-validation setting for their ancestry composition.

The test compares your DNA with reference populations from around the world to estimate your ethnic background.

However, it’s important to remember that this is still an estimate.

There can be overlapping genetic similarities between different world populations, and this can sometimes lead to less precise estimates.

The accuracy of your ancestry report will also be higher for regions that have more reference samples.

How Accurate is 23andMe Health and Carrier Status Report?

23andMe provides several health-related reports that fall into two main categories:

• Health Predisposition Reports
• Carrier Status Reports.

Health Predisposition Reports

These reports inform users of their genetic risk of developing certain health conditions.

For example, 23andMe tests for genetic variants associated with an increased risk of Type 2 diabetes, Parkinson’s disease, and late-onset Alzheimer’s disease, among others.

23andMe uses what is known as SNP genotyping to determine these predispositions.

This process looks for specific variants at certain locations within your DNA.

When these variants are known to be associated with a certain health condition, their presence may indicate an increased risk.

The accuracy of these reports is generally high for the variants they test.

The 23andMe test is designed to be highly accurate at detecting whether these specific variants are present or absent, with a reported accuracy greater than 99%.

However, it’s crucial to understand that these tests only look for specific variants, not all possible variants linked to these conditions.

Try the ACTGenes DNA Health Report

Carrier Status Reports

Carrier Status Reports identify whether a person carries a genetic variant for a condition that could be passed on to their children.

This includes conditions like cystic fibrosis, sickle cell anemia, and hereditary hearing loss.

Just like Health Predisposition Reports, these reports also have high accuracy for the variants they test for.

The carrier status tests are based on recommendations from the American College of Medical Genetics (ACMG), and the variants tested are those most commonly associated with these diseases in the broader population.

Try the ACTGenes Carrier Status Report

Limitations

While 23andMe’s health-related tests are generally accurate for the specific variants they test, it’s important to remember that they don’t provide a complete picture of your overall risk for these conditions.

Most health conditions are multifactorial, meaning they’re influenced by multiple genes, as well as environmental and lifestyle factors.

For example, the BRCA1/BRCA2 (Selected Variants) report offered by 23andMe tests for three variants in the BRCA1 and BRCA2 genes associated with an increased risk for breast and ovarian cancer.

Try the ACTGenes BRCA and Breast Cancer Analysis

However, there are over 1,000 known variants in these genes that can increase cancer risk, and the test doesn’t screen for all of them.

This means a negative result doesn’t eliminate your risk.

Moreover, genetic predisposition doesn’t guarantee that you will or will not develop a condition, it just implies a higher or lower-than-average risk.

Therefore, it’s always recommended that results from DTC genetic tests like 23andMe be interpreted with the help of a healthcare professional or a genetic counselor.

Importance of Professional Genetic Counseling

23andMe strongly advises customers to seek professional genetic counseling, especially when interpreting health-related genetic reports.

A genetic counselor can provide a full context for understanding the results, as well as guidance on any potential next steps.

In Conclusion

In general, 23andMe provides accurate results for the specific genetic variants it tests.

However, as with any genetic test, the results should not be used as a definitive answer about your ancestry, health, or traits.

The reports offer probabilities and risk estimates, not diagnoses.

If you’re considering a 23andMe test for health reasons, it’s important to discuss your intentions with a healthcare professional or a genetic counselor.

They can help you understand what the results can and cannot tell you, and guide you on any necessary follow-up actions.

References

1. 23andMe. (2021). 23andMe for Medical Professionals. https://medical.23andme.com/
2. Tandy-Connor, S., Guiltinan, J., Krempely, K., LaDuca, H., Reineke, P., Gutierrez, S., … & Holladay, J. (2018). False-positive results released by direct-to-consumer genetic tests highlight the importance of clinical confirmation testing for appropriate patient care. Genetics in Medicine, 20(12), 1515-1521.
3. Ancestry Composition Guide for 23andMe scientists. https://www.23andme.com/ancestry-composition-guide/