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What the TP53 gene does, and why an inherited fault matters | CION Cancer Clinics
TP53 is one of the body's most important safety genes. It makes a protein that stops damaged cells from dividing and, when the damage is too great, makes them die. A fault in TP53 present from birth causes Li-Fraumeni syndrome, a rare condition with a high risk of several cancers, some in childhood. This page explains what the gene does and what an inherited fault changes. 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 TP53 gene actually do?
- What jobs does the p53 protein do?
- How does an inherited TP53 fault raise cancer risk?
- What do the TP53 words on a report mean?
- An inherited TP53 fault and a tumour TP53 change, compared
- What do families get wrong about TP53?
- What this page cannot tell you
- Common questions about the TP53 gene
The short answer
What does the TP53 gene actually do?
TP53 is the gene that checks each cell for damage before it divides. It makes a protein called p53, which notices when the DNA inside a cell has been harmed, stops that cell from copying itself, and either lets repairs happen or tells the cell to die. When this check fails, damaged cells can keep dividing, and that is how many cancers begin.
Why doctors call it a guardian
Every day, cells in your body are harmed by sunlight, smoke, ageing and simple copying mistakes. Most of that damage never becomes a problem, because p53 catches it early. This is why TP53 is often called the guardian of the genome. It does not prevent damage. It decides what a damaged cell is allowed to do next.
Two ways TP53 turns up in cancer care
A TP53 change found inside a tumour is very common and is not inherited. A TP53 fault present from birth, in every cell of the body, is rare and is what causes Li-Fraumeni syndrome. This page is about the inherited kind. Tumour testing is explained under targeted therapy.
A TP53 fault is a statement about risk. It is not a diagnosis of cancer.Inside a healthy cell
What jobs does the p53 protein do?
p53 sits quietly in the cell most of the time. It springs into action only when something goes wrong.
It spots damage
When the DNA in a cell is broken or badly copied, p53 levels rise quickly. The protein acts like an alarm that the rest of the cell listens to.
It pauses the cell
p53 stops the cell from dividing while the damage is still there. This matters because a cell that divides with broken DNA passes the fault to every cell that comes after it.
It calls in repair
During the pause, p53 switches on other genes that fix the DNA. If the repair works, the cell carries on as normal and nobody ever knows anything happened.
Repair usually handles
- Everyday copying mistakes
- Damage from sunlight or smoke
- Small breaks in the DNA strand
It ends a cell beyond repair
If the damage is too great, p53 tells the cell to shut itself down in a tidy, planned way. Losing one cell is a small price. Keeping a badly damaged one is how tumours start.
Without working p53, a damaged cell is not stopped and not removed.Not sure whether this applies to you?
Ask an oncologistFrom fault to cancer
How does an inherited TP53 fault raise cancer risk?
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You carry two copies of TP53
One copy came from your mother and one from your father. One working copy is enough for p53 to do its job in a cell.
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An inherited fault knocks out one copy from birth
Someone with Li-Fraumeni syndrome starts life with one working copy in every cell instead of two. The cells still behave normally, because the second copy is covering.
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The second copy can be lost in a single cell
Wear and tear, copying errors or radiation can damage that remaining copy in one cell. Now that cell has no guardian at all.
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That cell can grow unchecked
With no p53, damage piles up and the cell keeps dividing. Because this can happen in almost any tissue, a TP53 fault is linked to many different cancers, some of them in childhood.
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Risk is high, but not certain
Whether that second step happens is partly chance. Two carriers in one family can have very different lives, which is why regular checks aim to find any cancer early.
On your report
What do the TP53 words on a report mean?
- TP53
- The name of the gene. It is written in capital letters and italics on most reports.
- p53
- The protein the gene makes. It is the protein, not the gene, that does the checking inside the cell.
- Tumour suppressor gene
- A gene whose normal job is to hold back cell growth. TP53 is the best known example.
- Li-Fraumeni syndrome
- The condition caused by an inherited TP53 fault. Some reports now call it heritable TP53-related cancer syndrome.
- Germline
- Present in every cell from birth, and so able to pass to children. This is the kind that matters for the family.
- Somatic
- Found only inside the tumour. It arose during life and cannot be passed on.
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Side by side
An inherited TP53 fault and a tumour TP53 change, compared
Inherited (germline) fault
Change in the tumour (somatic)
Present in every cell from birth
Present only in the cancer cells
Rare in the population
Very common across many cancers
Found with a blood or saliva test
Found with a test on tumour tissue
Children and siblings may carry it
Nothing passes to the family
Leads to lifelong checks for the carrier
Informs treatment of that one cancer
Commonly believed
What do families get wrong about TP53?
"The report says TP53, so my children are at risk."
Only if the fault is inherited. Most TP53 changes reported in cancer care come from tumour tests and stay inside the tumour. Ask whether your report came from blood or from tissue before worrying about the family.
"A TP53 fault causes one type of cancer."
An inherited fault is linked to several. The most common are breast cancer at a young age, bone and soft tissue sarcomas, brain tumours and adrenal gland tumours in children. This spread is what makes the syndrome recognisable.
"Nobody in the family had cancer, so it cannot be TP53."
A TP53 fault can appear for the first time in one person, with neither parent carrying it. That person can still pass it to their own children.
"With a TP53 fault, cancer is certain, so checks are pointless."
Risk is high, but it is not certainty. Regular checks planned for TP53 carriers aim to catch tumours early, when they are smaller and easier to treat.
Being straight with you
What this page cannot tell you
It cannot tell you whether you or your family carry a TP53 fault. Only a germline test, arranged after a genetic counsellor has drawn your family tree, can answer that. It also cannot say what a particular TP53 variant on your report means. What your specific variant means is a question for the counsellor who ordered the test.
It cannot put a number on your own risk
Studies of TP53 carriers come from a limited number of families, mostly outside India. Risk differs by the exact variant and by family, and figures you find online may not fit yours. A counsellor can explain what is known and what is still uncertain.
Who this does not apply to
Most people do not need a TP53 test. If TP53 appeared only on a tumour report, and your family has no pattern of young or unusual cancers, it is very likely a change in the tumour alone. Your oncologist or a counsellor can tell you whether a blood test is worth doing.
Questions we are asked
Common questions about the TP53 gene
Is TP53 the same thing as Li-Fraumeni syndrome?
No. TP53 is a gene that everyone has. Li-Fraumeni syndrome is the condition a person has when they are born with a faulty copy of that gene in every cell. A TP53 change found only in a tumour does not mean Li-Fraumeni syndrome.
Which cancers are linked to an inherited TP53 fault?
The main ones are breast cancer at a young age, sarcomas of bone and soft tissue, brain tumours, adrenal gland tumours in children and some blood cancers. Other cancers can occur too. A counsellor will explain which checks matter for you and at what ages.
Why do TP53 cancers sometimes start in childhood?
Because the guardian gene is already missing one copy from birth, fewer further steps are needed before a cell escapes control. That is why some cancers in TP53 families appear in children and young adults, and why checks for carriers can start early in life.
Can an inherited TP53 fault be repaired?
No. A gene fault present from birth cannot be corrected or reversed with any current treatment. What can change is how early a cancer is found. Regular checks, and avoiding unnecessary radiation, are how carriers are looked after.
How is an inherited TP53 fault found?
With a blood or saliva test, usually as part of a panel of cancer genes. It is normally arranged after counselling, often starting with the relative who already had cancer. A result from tumour tissue alone cannot confirm an inherited fault.
If my parent has a TP53 fault, will I have it?
Each child of a carrier has a one in two chance of inheriting the fault, whether the parent is the mother or the father. A child who did not inherit it cannot pass it on. A test for the known family fault gives a clear answer.
Does lifestyle matter if I carry a TP53 fault?
Yes. Not smoking, limiting alcohol, protecting skin from strong sun and avoiding radiation that is not truly needed all reduce extra damage to cells. None of this removes the inherited risk, but each one takes away something that could add to it.
Can I get counselling about TP53 in Telugu?
You can ask for it. Counselling in your own language makes a real difference to understanding a result like this. Call the CION helpline, say you want to discuss a TP53 result, and ask for a Telugu-speaking counsellor or oncologist.
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 — TP53 gene
- MedlinePlus Genetics — Li-Fraumeni syndrome
- GeneReviews (NCBI) — Li-Fraumeni Syndrome
- 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
TP53 mutation: which cancers and what riskThe cancers linked to an inherited fault, in plain termsGermline TP53 vs a TP53 change in the tumourCheck which kind of TP53 result you are holdingTP53 positive: what happens nextThe first weeks and the checks that follow a resultChompret criteria and when TP53 testing is offeredWhether your family history qualifies for a test
Talk to us
Found TP53 on a report and not sure what it means?
Tell us whether the result came from a blood test or a tumour sample, and who in the family has had cancer. We will help you reach a counsellor who can explain it properly. One helpline serves every CION centre.