BRCA Gene Test from 23andMe Raw Data: What You Can Learn

The BRCA genes are arguably the most well-known cancer risk genes in the world. Since Angelina Jolie's 2013 op-ed about her decision to undergo a preventive double mastectomy after testing positive for a BRCA1 mutation, public awareness has skyrocketed. Millions of people now want to know: do I carry a BRCA mutation?

If you've done a 23andMe test, you might assume you've already been checked. The truth is more nuanced - and understanding what 23andMe does and doesn't test for could be one of the most important health decisions you make.

What Are BRCA1 and BRCA2?

BRCA1 (Breast Cancer gene 1) and BRCA2 (Breast Cancer gene 2) are tumor suppressor genes. Their normal function is to produce proteins that help repair damaged DNA - they're essentially part of your body's cancer prevention system (Yoshida & Miki, 2004).

When one of these genes carries a pathogenic (harmful) mutation, the DNA repair mechanism is compromised. This significantly increases the risk of several cancers:

Cancer Risks Associated with BRCA Mutations

| Cancer Type | General Population Risk | BRCA1 Mutation | BRCA2 Mutation |
|---|---|---|---|
| Breast cancer (female) | ~13% lifetime | 55–72% | 45–69% |
| Ovarian cancer | ~1.2% lifetime | 39–44% | 11–17% |
| Breast cancer (male) | ~0.1% lifetime | 1–2% | 6–8% |
| Prostate cancer | ~13% lifetime | Moderately increased | Up to 30% |
| Pancreatic cancer | ~1.5% lifetime | Increased | 2–7% |

Risk estimates from the National Cancer Institute (NCI, 2024) and Kuchenbaecker et al. (2017).

Key point: Having a BRCA mutation doesn't mean you'll definitely get cancer - it means your risk is significantly elevated. And knowing about it opens the door to screening, prevention, and early detection strategies that can save lives.

What Does 23andMe Actually Test for BRCA?

Here's where most people get confused. 23andMe's Health + Ancestry service includes a "BRCA1/BRCA2 (Selected Variants)" report. But the word "selected" is doing a lot of heavy lifting.

23andMe Tests Only 44 Variants

As of their most recent panel, 23andMe tests for 44 specific BRCA1/BRCA2 variants - including the three Ashkenazi Jewish founder mutations that received the most attention:

1. BRCA1 185delAG (c.68_69delAG)
2. BRCA1 5382insC (c.5266dupC)
3. BRCA2 6174delT (c.5946delT)

These three variants are found at elevated frequency in individuals of Ashkenazi Jewish descent (approximately 1 in 40 carry one of these mutations). 23andMe later expanded to include additional variants, but the total coverage remains extremely limited.

The Problem: Over 1,000 Known Pathogenic BRCA Variants Exist

The ClinVar database lists over 1,000 pathogenic and likely pathogenic variants in BRCA1 and BRCA2 combined (Landrum et al., 2018). 23andMe's 44 variants represent roughly 4% of known pathogenic variants.

This means that a negative result from 23andMe does not mean you don't carry a BRCA mutation. You could carry one of the 95%+ of pathogenic variants that 23andMe doesn't test.

The FDA-authorized report explicitly states this - but many consumers miss the fine print.

What Can You Learn from Your Raw Data?

Your 23andMe raw data file contains information on all SNPs (single nucleotide polymorphisms) present on the genotyping chip - typically 600,000–700,000 variants. Some of these SNPs fall within or near the BRCA1 and BRCA2 genes.

What Raw Data Analysis Can Reveal

By analyzing your raw data with a tool like GenomeInsight, you can check for:

• Additional BRCA SNPs beyond the 44 that 23andMe reports on
• Variants flagged in ClinVar as pathogenic or likely pathogenic
• Research-associated variants with emerging evidence
• Population-specific variants that may be relevant to your ancestry

What Raw Data Analysis Cannot Do

It's critical to understand the limitations:

• Consumer genotyping chips are not sequencing. They test for pre-selected variants, not every possible mutation in the gene. Novel or rare mutations that aren't on the chip will be invisible.
• Raw data analysis cannot replace clinical BRCA testing. Clinical tests use full gene sequencing (and often deletion/duplication analysis) to examine every base pair of BRCA1 and BRCA2.
• Some pathogenic variants require sequencing to detect - particularly large deletions, insertions, and rearrangements that genotyping arrays don't capture.

The Value of Raw Data Screening

So why bother? Because raw data screening can:

1. Catch variants 23andMe's report didn't show you - there may be BRCA-related SNPs in your raw data that fell outside 23andMe's curated 44-variant report
2. Flag potential risks for follow-up - if raw data analysis suggests a concerning variant, you can pursue confirmatory clinical testing
3. Provide context - understanding what's in your data helps you have informed conversations with genetic counselors
4. It's data you already have - no additional cost or testing required

Think of raw data analysis as a first-pass screen, not a definitive test. It's the difference between a screening mammogram and a diagnostic biopsy - both valuable, but serving different purposes.

Who Should Consider Clinical BRCA Testing?

The National Comprehensive Cancer Network (NCCN) recommends genetic counseling and potential BRCA testing for individuals with (NCCN, 2024):

• Personal history of breast cancer diagnosed at age 50 or younger
• Triple-negative breast cancer diagnosed at age 60 or younger
• Ovarian cancer at any age
• Male breast cancer at any age
• Pancreatic cancer with Ashkenazi Jewish heritage
• Known BRCA mutation in the family
• Multiple family members with breast, ovarian, prostate, or pancreatic cancer

Family History Matters

Even with a negative raw data result, strong family history warrants clinical evaluation. A genetic counselor can assess your family pedigree and recommend appropriate testing - which may include full BRCA1/2 sequencing and large rearrangement testing.

How to find a genetic counselor:

• National Society of Genetic Counselors - Find a counselor directory
• Many hospital cancer centers offer genetic counseling services
• Telehealth genetic counseling is increasingly available

Understanding Your BRCA Results

If You Find a Known Pathogenic Variant

If raw data analysis flags a variant classified as pathogenic or likely pathogenic in ClinVar:

1. Don't panic - a finding in raw data needs confirmation
2. Get confirmatory testing - contact your doctor or a genetic counselor to order clinical-grade BRCA testing
3. Don't make medical decisions based solely on consumer genetic data
4. Know that actionable options exist - enhanced screening (breast MRI, more frequent mammograms), risk-reducing medications, and preventive surgery are all evidence-based options for confirmed carriers

If You Find a Variant of Uncertain Significance (VUS)

Many BRCA variants are classified as "uncertain significance" - meaning there isn't enough evidence to determine if they're harmful or benign. A VUS result should not change your medical management. Over time, many VUS are reclassified as benign as more data accumulates.

If Your Raw Data Shows No Concerning Variants

A negative raw data result is reassuring but not definitive. Remember:

• The genotyping chip only tests pre-selected positions
• Rare or novel mutations won't be detected
• If you have significant family history, clinical testing is still recommended regardless of raw data results

How to Check Your BRCA Status with GenomeInsight

1. Download your raw data from 23andMe (or AncestryDNA, or another service)
2. Visit GenomeInsight's upload page
3. Select your file - analysis happens entirely in your browser
4. Review the Cancer Risk section of your report, which includes BRCA1/BRCA2 variant analysis

GenomeInsight cross-references your raw data against ClinVar classifications and flags any variants with clinical significance. All processing happens client-side - your genetic data never leaves your device, which is especially important for sensitive health information like cancer risk.

Not ready to upload your own data? Try the free demo to see what a BRCA section looks like in a GenomeInsight report.

The Bigger Picture: Genetic Cancer Screening Beyond BRCA

While BRCA1 and BRCA2 get the most attention, they're not the only cancer-related genes. Other genes associated with hereditary cancer risk include:

| Gene | Associated Cancers |
|---|---|
| TP53 | Li-Fraumeni syndrome  -  breast, bone, brain, adrenal |
| PALB2 | Breast, pancreatic |
| CHEK2 | Breast, colon |
| ATM | Breast, pancreatic |
| MLH1, MSH2, MSH6, PMS2 | Lynch syndrome  -  colon, endometrial, ovarian |
| CDH1 | Hereditary diffuse gastric cancer, lobular breast cancer |
| PTEN | Cowden syndrome  -  breast, thyroid, endometrial |

GenomeInsight's health report checks for variants across multiple cancer-related genes - not just BRCA - giving you a broader picture of your genetic cancer risk profile.

Frequently Asked Questions

Can 23andMe tell me if I have BRCA?

Only partially. 23andMe tests for 44 specific BRCA variants out of over 1,000 known pathogenic variants. A negative 23andMe BRCA result does not mean you're BRCA-negative.

How much does clinical BRCA testing cost?

Clinical BRCA testing ranges from $250 to over $4,000, depending on the laboratory and scope. Insurance often covers testing for individuals who meet NCCN criteria. Companies like Color and Invitae have offered testing at lower price points, though availability varies.

Can men carry BRCA mutations?

Yes. BRCA mutations are inherited in an autosomal dominant pattern - men and women are equally likely to carry them. Male BRCA carriers face increased risks for breast cancer, prostate cancer, and pancreatic cancer, and can pass the mutation to their children.

Should I get tested if no one in my family has had cancer?

Family history is a strong indicator, but not the only one. Some BRCA carriers have no family history of cancer (due to small family size, incomplete information, or chance). If you have raw data available, screening it is a low-cost, zero-risk way to check for common variants.

Is raw data BRCA screening a substitute for clinical testing?

No. Raw data screening is a useful first step but cannot replace full gene sequencing. Think of it as a preliminary screen - if it finds something concerning, pursue clinical testing. If it finds nothing, and you have risk factors, clinical testing is still recommended.

Take the First Step

Understanding your BRCA status is one of the most actionable things you can do with your genetic data. While raw data analysis isn't a replacement for clinical testing, it's a powerful, private, and free (with your existing data) first step.

Upload your raw data to GenomeInsight to check your BRCA variants along with hundreds of other clinically relevant genetic markers -- all processed privately in your browser.

Related Reading

• BRCA Gene and Breast Cancer Risk -- a deeper look at how BRCA1 and BRCA2 mutations affect lifetime cancer risk and what screening options are available.
• Lynch Syndrome Genetic Testing -- another hereditary cancer syndrome you can screen for using raw DNA data.
• DNA Health Risks: What Your Genes Can Tell You -- an overview of the health conditions you can explore with consumer genetic data.

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Disclaimer: This article is for informational and educational purposes only. It is not a substitute for professional medical advice, genetic counseling, or clinical genetic testing. If you have concerns about hereditary cancer risk, consult a genetic counselor or healthcare provider. GenomeInsight's raw data analysis is a screening tool and does not replace clinical-grade BRCA testing.

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Related Reading

• 23andMe data concerns