What is the difference between BRCA1 and BRCA2 gene mutations?

BRCA1 and BRCA2 are two different genes that both help repair damaged DNA in your cells. When either gene carries a harmful change (a pathogenic variant or mutation), your risk of several cancers increases-but the two genes behave differently. Knowing which gene is affected helps you and your doctors plan the right screening schedule, consider risk-reducing options, and understand what to watch for in your family.

What BRCA1 and BRCA2 have in common

Both genes produce proteins that act as ‘DNA repair workers’. When cells divide, mistakes happen in the genetic code. BRCA1 and BRCA2 proteins fix those mistakes before they pile up. If you inherit a faulty copy of either gene, your cells can’t repair DNA as efficiently, and cancer-causing errors accumulate over time.

Shared features:

• Autosomal dominant inheritance. You need only one faulty copy (from one parent) to have elevated cancer risk. Each of your children has a 50% chance of inheriting the same variant.
• Increased risk of breast and ovarian cancer. Both genes are most strongly linked to these two cancers in women, though men with BRCA mutations face risks too.
• Eligibility for enhanced NHS surveillance. If you test positive for a pathogenic BRCA1 or BRCA2 variant, you qualify for annual breast MRI from age 30 (sometimes earlier) and risk-reducing surgery discussions under NHS clinical genetics services.
• Actionable findings. Knowing you carry a BRCA mutation changes medical management-screening starts earlier and happens more often, and preventive options (like risk-reducing mastectomy or removal of ovaries and fallopian tubes) become available.

Despite these commonalities, the genes sit on different chromosomes (BRCA1 on chromosome 17, BRCA2 on chromosome 13), produce different proteins, and lead to different cancer-risk profiles.

Key differences in cancer risk

Breast cancer risk and age of onset

BRCA1 mutations typically cause more aggressive, earlier-onset breast cancers. By age 70, around 70–80% of women with a harmful BRCA1 variant will develop breast cancer, and the risk rises steeply in the 30s and 40s. BRCA1-related breast cancers are more often triple-negative (oestrogen receptor–negative, progesterone receptor–negative, HER2-negative), which means they don’t respond to hormone therapies like tamoxifen and tend to grow faster.

BRCA2 mutations also raise breast-cancer risk substantially-around 60–70% by age 70-but onset tends to come slightly later (more commonly in the 40s and 50s), and the tumours are more often hormone receptor–positive. That means they may respond to hormone-blocking drugs, and treatment options are broader.

Men with BRCA2 mutations face a notably higher breast-cancer risk than men with BRCA1 variants (around 6–8% lifetime risk vs 1–2%), though both are much higher than the general male population risk of less than 1%.

Ovarian cancer risk

Both genes raise ovarian-cancer risk, but again the numbers differ.

• BRCA1: Around 40–45% lifetime risk of ovarian cancer (including fallopian-tube and primary-peritoneal cancers, which behave similarly). Risk increases from the mid-30s onward.
• BRCA2: Around 10–20% lifetime risk-still far above the general population’s 1–2%, but lower than BRCA1.

Because of these differences, some women with BRCA2 mutations may opt to delay risk-reducing surgery slightly longer than those with BRCA1, though the decision is highly individual and should involve specialist genetic counselling.

Other cancers

Both genes are linked to a wider cancer spectrum, but the secondary risks diverge:

• Prostate cancer: BRCA2 mutations confer a higher and earlier prostate-cancer risk than BRCA1. Men with BRCA2 variants may be eligible for earlier PSA screening (sometimes from age 40) and should discuss this with their GP.
• Pancreatic cancer: BRCA2 is more strongly associated with pancreatic cancer than BRCA1 (roughly 3–5% lifetime risk vs 1–2%). Families with multiple pancreatic-cancer cases and a known BRCA2 mutation may qualify for surveillance programmes, though these remain limited in the UK.
• Melanoma and other cancers: Some studies link BRCA2 to modestly increased melanoma risk; the evidence for BRCA1 is weaker.

Tumour biology

BRCA1-associated breast cancers tend to be higher-grade (fast-growing) and triple-negative more often. BRCA2-associated cancers more closely resemble sporadic (non-inherited) breast cancers in receptor status, which can make them slightly easier to treat with existing hormone therapies. However, both BRCA1 and BRCA2 tumours often respond well to platinum chemotherapy and PARP inhibitors-drugs that exploit the underlying DNA-repair defect.

Does it matter which gene I have?

Yes, for three reasons:

1. Screening schedules may differ slightly. NICE and NHS guidelines are broadly similar for BRCA1 and BRCA2, but some centres offer earlier or more intensive ovarian surveillance for BRCA1 carriers.
2. Risk-reducing surgery timing. Because BRCA1 ovarian-cancer risk rises earlier, many specialists recommend removing the ovaries and fallopian tubes (risk-reducing salpingo-oophorectomy) by age 35–40 once childbearing is complete. For BRCA2, the window may extend to 40–45, though individual family history and patient preference matter more than rigid cutoffs.
3. Family implications. If a relative tests positive for BRCA2 and you’re male, you need to know your prostate-cancer risk is elevated. If your sister has BRCA1, she needs to know triple-negative breast cancer is more likely and screening should start younger.

How testing works and what happens next

BRCA1 and BRCA2 are tested together in most panels-there’s no reason to test only one. If you have a strong family history of breast, ovarian, prostate or pancreatic cancer, or if a relative has already tested positive, your GP can refer you to NHS clinical genetics for free testing. Waiting times vary by region, and not everyone meets the NHS referral criteria.

Private testing (including Jeen’s panels) sequences both genes plus related cancer-predisposition genes, so you get a comprehensive answer in one go. Results typically come back in 3 weeks, and genetic counselling helps you interpret what the findings mean for you and your relatives.

What you can do at Jeen

If you don’t meet NHS criteria or want faster access, Jeen offers several BRCA-pathway testing options:

• BRCA Testing: Our 10-gene BRCA-pathway panel covers BRCA1, BRCA2 and the most actionable related genes linked to hereditary breast, ovarian, prostate and pancreatic cancer. The test includes 45-minute specialist genetic counselling and NHS Genomic Medicine Service-aligned variant interpretation, with an at-home buccal swab kit. If you prefer a blood sample, the draw isn’t included in the test price: you can arrange your own at no extra cost, or we can arrange a draw at a partner collection point (+£40) or a home-nurse visit (+£65). Results typically arrive within 17-21 working days from when your sample reaches the laboratory-often much faster than NHS waiting lists.

• Breast Cancer Risk Screening (13-gene panel) and Ovarian Cancer Risk Screening (14-gene panel) offer more focused testing if your family history points to one cancer type. Both include genetic counselling and the same sample-collection options, with the same blood-draw charges.

• Pancreatic Cancer Risk Screening (11-gene panel) is appropriate if pancreatic cancer runs in your family alongside BRCA-related cancers.

• Combined Cancer + Carrier Screening bundles a 50-gene hereditary-cancer panel with our 1,008-gene carrier-screening panel-useful if you’re planning a family and want both your cancer predisposition and recessive-disease carrier status assessed in one test.

All Jeen tests use NHS-aligned interpretation standards and include genetic counselling to help you understand your results and next steps.