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CION Cancer Clinics
The RAD51D gene: what it does and why it matters | CION Cancer Clinics
RAD51D is a gene that helps your cells mend DNA when both strands break at once. It works in the same repair system as BRCA1 and BRCA2, as part of a small team of helper proteins. A fault in RAD51D mainly raises the risk of ovarian cancer, and to a lesser degree breast cancer. This page explains what the gene does, what a fault changes and what it does not. At CION Cancer Clinics, our oncologists explain what a gene result means for you and your family, and plan the checks that follow.
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Medically reviewed by Dr. Naresh GunduConsultant Medical Oncologist · MBBS, DNB (Internal Medicine), DM (Medical Oncology, AIIMS) · last reviewed September 2026, next review due September 2027
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On this page
- What does the RAD51D gene actually do?
- Which cancers does a RAD51D fault affect?
- How does a faulty repair gene raise cancer risk?
- What do the words on a RAD51D report mean?
- How does RAD51D compare with BRCA1 and BRCA2?
- What this page cannot tell you
- Four things families believe about RAD51D, and what is true
- Common questions about the RAD51D gene
The short answer
What does the RAD51D gene actually do?
RAD51D gives the cell instructions for a protein that helps repair double-strand breaks, the most dangerous kind of DNA damage. It does this by helping another protein, called RAD51, copy the missing information from the matching chromosome. When RAD51D is faulty, that repair is less accurate, and damaged cells are more likely to survive and go wrong.
Why DNA breaks at all
DNA is damaged every day. Some damage comes from ordinary cell division, and some from outside causes such as tobacco smoke or radiation. Most of it is mended quickly. Double-strand breaks are rarer but harder to fix, and a cell that cannot fix them properly slowly gathers errors.
Why RAD51D is often named alongside RAD51C
The two genes make neighbouring members of the same small repair team. A fault in either one produces a similar pattern: a clear rise in ovarian cancer risk, a smaller rise in breast cancer risk, and little clear risk for men themselves. That is why counsellors often explain them together, and why the plans for carriers of each look alike.
A RAD51D fault is a statement about risk. It is not a diagnosis of cancer.Where the risk sits
Which cancers does a RAD51D fault affect?
The evidence is strongest for the ovary and weaker elsewhere. Any honest summary says so.
Ovarian cancer
The clearest link. A fault raises lifetime risk well above that of the general population, though most carriers never develop it. There is no reliable screening test, so this risk drives most decisions.
What it usually leads to
- A later conversation about removing the ovaries and tubes
- Knowing which symptoms to report early
Breast cancer
A moderately raised risk, seen more often as the type called triple-negative. Breast checks are planned from both the result and your family history, rather than from the gene alone.
Other cancers
Links to prostate and other cancers have been suggested in some studies. They are not confirmed, and the studies so far are small. Care should not change on the strength of an unproven link.
Men who carry it
A man has no clearly raised cancer risk of his own. He can still pass the fault to his daughters and sons, so men belong in the family tree and in family testing.
Not sure whether this applies to you?
Ask an oncologistFrom fault to risk
How does a faulty repair gene raise cancer risk?
Two copies from birth
Everyone inherits one copy of RAD51D from each parent. One working copy is normally enough to keep DNA repair running smoothly.
One copy is faulty in a carrier
A carrier is born with only one working copy in every cell. Nothing feels different, and nothing is wrong yet.
The working copy is lost in one cell
Over many years, the remaining copy can be damaged in a single cell, often in the ovary or fallopian tube. That cell can no longer mend double-strand breaks accurately.
Errors pile up slowly
Each time that cell divides, new mistakes are added. The body clears most such cells. Occasionally one grows into a tumour, usually in later adult life.
On your report
What do the words on a RAD51D report mean?
- Double-strand break
- A break across both strands of the DNA ladder at the same point. The most serious kind of DNA damage.
- Homologous recombination
- The repair method RAD51D helps with. The cell copies the missing piece from the matching chromosome.
- RAD51 paralog
- One of a small family of related genes, including RAD51C and RAD51D, that support the main repair protein.
- Heterozygous
- One faulty copy and one working copy, which is what almost every carrier has.
- Moderate penetrance
- The fault raises risk clearly, but less than the strongest genes, and many carriers never develop cancer.
- Variant of uncertain significance
- A change the laboratory cannot yet classify. It should not change your care or lead to surgery.
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Side by side
How does RAD51D compare with BRCA1 and BRCA2?
RAD51D
BRCA1 and BRCA2
Ovarian risk clearly raised, but lower
Ovarian risk higher, especially with BRCA1
Breast risk moderately raised
Breast risk high
Ovarian surgery usually discussed later
Ovarian surgery discussed at a younger age
Preventive breast surgery not routinely advised
Preventive breast surgery commonly discussed
A newer gene, with smaller studies
Studied for decades, in very large numbers
Being straight with you
What this page cannot tell you
It cannot tell you what your own result means. RAD51D is a newer gene in routine testing, and its risk figures are still being refined as larger studies report. What your specific variant means is a question for the counsellor who ordered the test.
It cannot give you a personal risk figure
Average figures hide a lot. Your age, and how many relatives had ovarian or breast cancer and at what age, can shift your risk well above or below the average. A counsellor uses all of that to give you a figure that fits your family, and explains how sure anyone can be about it.
Who this does not apply to
Most people never need a RAD51D test. It is usually checked as part of a panel when a family has ovarian cancer, or several early breast cancers. If your report lists RAD51D only as tested, with nothing found, this page does not apply to you. A RAD51D change found only in a tumour is a question about treatment, covered under targeted therapy.
Commonly believed
Four things families believe about RAD51D, and what is true
"RAD51D is just another BRCA gene."
It works in the same repair system, which is why they are often grouped. It is a separate gene, with a lower level of risk and its own plan.
"A fault means I will get ovarian cancer."
Most carriers never develop ovarian cancer. The fault raises the chance, and planning around it can lower that chance again.
"Men cannot carry it."
Men carry and pass on RAD51D faults exactly as women do. They simply have no clearly raised risk of their own.
"An uncertain result is almost a positive one."
A variant of uncertain significance is not a positive result. Many are later reclassified as harmless, and none should lead to surgery.
Questions we are asked
Common questions about the RAD51D gene
Is RAD51D the same as RAD51C?
No, they are two separate genes, but they make partner proteins in the same repair team. Faults in either one raise ovarian cancer risk in a similar way, which is why they are often discussed together. Your report will name the exact gene, and the plan follows that gene.
How is a RAD51D fault inherited?
It follows a dominant pattern. A parent with one faulty copy has a one in two chance of passing it to each child, son or daughter. The fault does not skip generations, though cancer may not appear in every carrier.
Why was RAD51D on my test at all?
Most panels offered for ovarian or breast cancer in a family include RAD51D, along with BRCA1, BRCA2 and several others. Seeing it listed means it was checked. It does not mean a fault was found unless the report clearly says so.
Is there a screening test for ovarian cancer?
Not one that reliably finds it early. Blood tests and ultrasound scans have been studied, but they do not work well enough to rely on. That is why carriers usually discuss removing the ovaries and tubes later in adult life instead.
Does RAD51D affect men's health?
A clearly raised risk for men has not been shown. Some studies have looked at prostate cancer, but the evidence is not strong enough to change care. Men matter here mainly because they can pass the fault to their daughters and sons.
Can a RAD51D fault change cancer treatment?
Sometimes. Ovarian cancers with weak DNA repair may respond to tablets called PARP inhibitors. If you already have cancer, your oncologist will say whether this applies, based on your tumour and your result together.
Should my children be tested now?
Usually not. RAD51D risks start in adult life, so testing is normally offered once a child is an adult and can choose. Make sure they know the result exists, so they can decide when the time comes.
Where can I have my RAD51D result explained?
A genetic counsellor is the right person. Call the CION helpline and someone will book a counselling appointment, in Telugu if you prefer, and help you plan who else in the family should be told.
Your Specialists
Meet CION's oncologists. Bring your family history or genetic report to them.
Our medical oncologists see people with a strong family history of cancer, arrange genetic counselling and testing where it fits, and plan the checks that follow.
Medical Oncologist
Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
Medical Oncologist
Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
Medical Oncologist
Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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Sources
- MedlinePlus Genetics — RAD51D gene
- National Cancer Institute — Genetics of Breast and Gynecologic Cancers (PDQ) - Health Professional Version
- NCCN — Genetic/Familial High-Risk Assessment: Breast, Ovarian, Pancreatic, and Prostate
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
RAD51D mutation: which cancers and what riskWhat the raised risk looks like in practiceRAD51D positive: what happens nextThe first steps after a positive resultTesting the family for RAD51DWho else in the family should be offered a testThe RAD51C gene: what it doesThe partner gene with a similar pattern of risk
Talk to us
Holding a report that mentions RAD51D?
A genetic counsellor can explain what your result means for you and your family, in Telugu if you prefer. One helpline serves every CION centre.