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What the PTCH1 and SUFU genes do, and why a fault matters | CION Cancer Clinics
PTCH1 and SUFU are two genes that act as brakes on a growth signal called the hedgehog pathway. When one copy of either gene is faulty from birth, that brake is weaker, and the result is Gorlin syndrome. This page explains what each gene normally does, how a fault leads to skin cancers, why the two genes carry different childhood risks, and why radiation matters so much. 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 do the PTCH1 and SUFU genes normally do?
- How do PTCH1 and SUFU faults differ?
- How does a faulty gene lead to a skin cancer?
- What do the gene words mean in plain language?
- PTCH1 and SUFU compared
- What this page cannot tell you
- Four things people assume about these genes
- Common questions about PTCH1 and SUFU
The short answer
What do the PTCH1 and SUFU genes normally do?
Both genes act as brakes on a growth signal called the hedgehog pathway. That signal tells cells when to grow and divide. PTCH1 and SUFU keep it switched off in cells that should be resting. When one copy of either gene is faulty from birth, the brake is weaker, and the result is Gorlin syndrome.
A signal that matters most before birth
The hedgehog pathway does much of its work while a baby is forming in the womb. It helps shape the face, the jaw, the ribs and the brain. That is why Gorlin syndrome can show in the skeleton, such as a larger head or an unusual rib, long before any skin cancer appears.
Two genes, two different steps
PTCH1 sits at the surface of the cell and holds the switch in the off position until a signal arrives. SUFU sits deeper inside the cell and holds back the proteins that carry the message to the cell's control centre. A fault at either step lets the signal run when it should be quiet.
PTCH1 is the common cause of Gorlin syndrome. SUFU is a much rarer one.Gene by gene
How do PTCH1 and SUFU faults differ?
They cause the same syndrome, but they do not carry exactly the same risks.
PTCH1
The gene behind most Gorlin syndrome. Carriers commonly develop many basal cell carcinomas in adult life, and jaw cysts from late childhood. Small pits on the palms and soles are common too. The childhood brain tumour risk is lower than with SUFU, which is why routine brain scans are not usually part of a PTCH1 child's plan.
SUFU
A rare cause. The most important difference is a clearly higher chance of medulloblastoma, a brain tumour of early childhood.
Reported so far
- Higher childhood brain tumour risk
- Jaw cysts less often than with PTCH1
- A raised chance of meningioma in adults
When neither gene shows a fault
Some people clearly have Gorlin syndrome on examination, yet testing finds no fault in either gene. They are still diagnosed and watched on their signs. The fault may sit in a part of the gene that standard tests read poorly, or be present in only some of the body's cells. Their relatives are then checked by examination rather than by a test.
Same fault, different lives
Two relatives with the same fault can look very different. One may have dozens of skin cancers, the other only a few. Doctors call this variable expressivity. It means a mild parent can still have a child who is more affected, so every carrier needs their own plan.
Not sure whether this applies to you?
Ask an oncologistFrom gene to growth
How does a faulty gene lead to a skin cancer?
Born with one faulty copy
Every cell carries two copies of each gene. A carrier is born with one faulty copy of PTCH1 or SUFU, in every cell.
One working copy holds the brake
For years, the remaining working copy keeps the hedgehog signal under control. The skin looks and behaves normally.
The second copy is lost in one cell
Sunlight, radiation or simple chance damages the working copy in a single skin cell. That cell now has no brake at all.
The signal stays on
The hedgehog signal runs constantly in that cell. Slowly, a basal cell carcinoma forms. The same process, in a developing brain, explains medulloblastoma in young children.
On your report
What do the gene words mean in plain language?
- Hedgehog pathway
- A chain of signals that tells cells when to grow. PTCH1 and SUFU keep it switched off.
- Tumour suppressor gene
- A gene that acts as a brake on growth. Both PTCH1 and SUFU are of this type.
- Germline
- Present in every cell from birth, so it can be passed to children. This is what a Gorlin test looks for.
- Somatic
- A change found only inside a tumour. It is not inherited and cannot be passed on.
- Second hit
- Damage to the remaining working copy of a gene in one cell. It is the step that lets a tumour start.
- Variable expressivity
- The same fault causing very different signs in different people, even within one family.
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Side by side
PTCH1 and SUFU compared
PTCH1
SUFU
The common cause of Gorlin syndrome
A rare cause
Jaw cysts are common
Jaw cysts are reported less often
Lower childhood brain tumour risk
Higher childhood brain tumour risk
Routine child brain scans usually not advised
Brain MRI in early childhood usually advised
Studied in many families
Known from far fewer families
Being straight with you
What this page cannot tell you
It cannot tell you what your own result means. Different faults in the same gene can behave differently, and some are still being studied. What your specific variant means is a question for the counsellor who ordered the test.
A tumour report is a different thing
PTCH1 changes are found inside many ordinary basal cell carcinomas, in people with no inherited fault at all. A PTCH1 change on a tumour report does not mean the family is affected. Tumour testing belongs under targeted therapy, not here.
Who this does not apply to
Most people do not need this test. A single basal cell carcinoma in later life, in someone with no jaw cysts, palm pits or family history, is almost never Gorlin syndrome. A counsellor will say so plainly if testing would not help you.
Knowledge about SUFU is still limited. Advice may change as more families are followed.Commonly believed
Four things people assume about these genes
"A faulty gene means every cell is already going wrong."
Every cell still has one working copy. Problems start only in the few cells where that second copy is later lost.
"The skin cancers are caused by the sun, not the gene."
In Gorlin syndrome they also appear on skin that rarely sees the sun. The gene is the main driver. Sunlight and radiation add extra damage on top of it.
"If it is in the genes, nothing we do makes a difference."
Sun protection and avoiding unnecessary X-rays both reduce the damage that leads to new skin cancers. Daily habits genuinely matter here.
"PTCH1 and SUFU are basically the same."
They work on the same signal, at different steps. That difference changes the childhood brain tumour risk, and so the checks a child needs.
Questions we are asked
Common questions about PTCH1 and SUFU
Why is it called the hedgehog pathway?
The name comes from early research in fruit flies. When the fly's version of the gene was missing, the larvae were covered in short spikes and looked a little like a hedgehog. The human genes kept the family name.
Is PTCH1 a cancer gene?
It is a gene that protects against cancer when it works. Only a faulty copy raises risk. Everyone has PTCH1 and SUFU, and in most people both copies work normally throughout life.
Did I inherit this from a parent?
Often, yes. In a real share of people, though, the fault appeared for the first time in them, and neither parent carries it. Testing the parents is the only way to know which applies to your family.
Why does the syndrome affect the bones and face?
The hedgehog signal helps shape the skeleton and face before birth. A weaker brake during that time can lead to a larger head, a broad bridge of the nose or a split rib. These features are harmless in themselves, but they help doctors recognise the syndrome.
Does the gene explain the radiation sensitivity?
Yes. Radiation can destroy the one working copy left in a skin cell, which is exactly the second hit that starts a basal cell carcinoma. This is why X-rays, CT scans and radiotherapy are used so carefully.
Can medicines target this signal?
Yes. Hedgehog inhibitor tablets block a step just after PTCH1, and can shrink many basal cell carcinomas. Because SUFU acts further down the chain, these tablets may work less well for SUFU-driven tumours. Your oncologist will weigh this.
Is PTCH1 and SUFU testing available in India?
Yes. Several laboratories test these genes, usually from a blood or saliva sample, often as part of a wider panel. Counselling before the test helps make sure the right genes are checked and that you understand what a result could mean.
My tumour report mentions PTCH1. Is that the same?
Not necessarily. A change found only in the tumour is usually not inherited. Only a blood or saliva test shows whether a fault is present from birth. Ask your oncologist which kind of test your report came from.
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 — PTCH1 gene
- MedlinePlus Genetics — SUFU gene
- GeneReviews (NCBI) — Nevoid Basal Cell Carcinoma Syndrome
- National Cancer Institute — Genetics of Skin Cancer (PDQ) – Health Professional Version
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
Gorlin syndrome explainedWhat the condition looks like in daily lifePTCH1 and SUFU: which cancers and what riskThe cancers these faults are linked toWhy Gorlin patients avoid radiation where possibleThe second hit, and how to avoid itTesting the family for PTCH1 and SUFUWho else in the family should be tested
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