Medical Oncologist
CION Cancer Clinics
The NF2, SMARCB1 and LZTR1 genes: what they do and why they matter | CION Cancer Clinics
NF2, SMARCB1 and LZTR1 all help stop the cells around nerves from growing out of control. A fault in one of them can lead to slow, non-cancerous tumours called schwannomas. NF2 faults usually affect the hearing nerves and start earlier in life. SMARCB1 and LZTR1 faults usually cause tumours on other nerves, often painful. This page explains what each gene does and why it matters. 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 NF2, SMARCB1 and LZTR1 genes actually do?
- What does each gene do inside the cell?
- How does a faulty gene lead to a schwannoma?
- The words you will meet, in plain language
- How does an NF2 fault compare with a SMARCB1 or LZTR1 fault?
- What this page cannot tell you
- Four things people assume about these genes
- Common questions about NF2, SMARCB1 and LZTR1
The short answer
What do the NF2, SMARCB1 and LZTR1 genes actually do?
All three help keep the cells that wrap around nerves from growing out of control. When one of them is faulty, those cells can form slow, non-cancerous tumours called schwannomas. A fault in NF2 causes NF2-related schwannomatosis. Faults in SMARCB1 or LZTR1 cause a related condition usually just called schwannomatosis.
Why these three are grouped together
They sit close to each other on the same chromosome, chromosome 22. That closeness matters. In schwannomatosis, a tumour usually forms when a large piece of that chromosome is lost in one cell, taking healthy copies of more than one of these genes with it. The genes work as a team, and they fail as a team.
Why this matters to you
Knowing which gene is faulty tells your doctors which tumours to look for, where to look and from what age. An NF2 fault usually means checks from childhood, focused on hearing. A SMARCB1 or LZTR1 fault usually means lighter checks in adult life, focused on pain and nerves elsewhere in the body.
These genes mainly cause benign tumours. Their harm comes from where the tumours grow.Gene by gene
What does each gene do inside the cell?
Each gene carries the instructions for one protein. Each protein does a different job, but all three jobs keep cell growth in check.
NF2
Makes a protein called merlin. Merlin acts as a brake. When a cell touches its neighbours, merlin tells it to stop dividing. Without it, cells around nerves and in the brain's lining keep growing.
SMARCB1
Part of a team of proteins that opens and closes stretches of DNA, switching other genes on or off. When it fails, genes that should stay quiet can switch on and push a cell to grow.
LZTR1
Helps the cell clear away a protein that carries a strong growth signal. When LZTR1 fails, that signal builds up and the cell is urged to divide.
What they have in common
All three are tumour suppressor genes. One working copy is usually enough.
Shared features
- All sit on chromosome 22
- All mainly affect cells around nerves
- All follow a dominant pattern in families
Not sure whether this applies to you?
Ask an oncologistFrom fault to tumour
How does a faulty gene lead to a schwannoma?
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A fault is present from birth
Someone who inherits a fault in one of these genes has one working copy instead of two, in every cell. Nothing is wrong yet. The working copy keeps the brake on.
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A second change happens in one nerve cell
During life, one cell around a nerve loses its working copy. In NF2 this can be a new fault or the loss of part of chromosome 22.
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In schwannomatosis, a third change is needed
With SMARCB1 or LZTR1, the lost piece of chromosome usually takes one copy of NF2 with it. A new fault in the remaining NF2 copy then completes the set. Because several steps are needed, many carriers never develop a tumour.
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The cell grows into a slow tumour
With its brakes gone, the cell divides and forms a schwannoma. Most grow slowly and stay in one place.
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Symptoms come from pressure
The tumour causes trouble by pressing on the nerve it grows from, or on the brain or spinal cord nearby. That is why its position matters more than its size.
On your report
The words you will meet, in plain language
- Tumour suppressor gene
- A gene whose normal job is to stop cells growing when they should not. Problems start when both copies stop working in one cell.
- Merlin
- The protein made by the NF2 gene. Some reports call it schwannomin.
- Schwann cell
- The cell that wraps around a nerve like insulation around a wire. Schwannomas grow from these cells.
- Germline
- Present in every cell from birth, and so able to pass to children. This is what a blood test for these genes looks for.
- Somatic
- A fault found only inside a tumour. Tumour testing belongs to a different kind of test, covered under targeted therapy.
- Loss of chromosome 22
- A report phrase meaning a tumour cell has lost part of the chromosome where these genes sit. It is found in the tumour, not inherited.
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Side by side
How does an NF2 fault compare with a SMARCB1 or LZTR1 fault?
NF2
SMARCB1 or LZTR1
Most carriers develop tumours
Many carriers never develop tumours
Tumours on both hearing nerves are typical
The hearing nerves are usually spared
Often first noticed as hearing loss or ringing
Often first noticed as pain along a nerve
Checks start in childhood
Checks usually start in adult life
Being straight with you
What this page cannot tell you
It cannot tell you whether you carry a fault in any of these genes. That needs a test, usually arranged after a genetic counsellor has looked at your symptoms, your scans and your family tree.
It cannot read the variant on your report
Different faults in the same gene can behave differently. In NF2, some types of change tend to cause more tumours at a younger age than others, but the pattern is not exact. What your specific variant means is a question for the counsellor who ordered the test.
Who this does not apply to
Most people with a single schwannoma do not carry a fault in any of these genes. A one-off tumour found in later life, with no family history and no other tumours, is usually a chance event in one cell. Testing is rarely helpful in that situation, and a counsellor will say so honestly.
Evidence on SMARCB1 and LZTR1 is still growing. Studies so far involve relatively small numbers of families.Commonly believed
Four things people assume about these genes
"NF2 is just a stronger form of NF1."
They are separate conditions caused by different genes on different chromosomes. NF1 mainly causes skin marks and growths on nerves in the skin. NF2 mainly causes tumours on the hearing nerves and around the brain.
"A gene fault means the tumours are cancer."
These genes almost always lead to non-cancerous tumours. The concern is pressure on nerves, not spread through the body.
"If I carry LZTR1, I will definitely get tumours."
Several separate changes must happen in one cell before a tumour forms. Many LZTR1 carriers never reach that point, which is why their checks are lighter.
"The tumour test and the blood test are the same thing."
A blood test looks for a fault you were born with. A tumour test looks for changes inside the growth itself. Both can be useful, and they answer different questions.
Questions we are asked
Common questions about NF2, SMARCB1 and LZTR1
Why is a cancer clinic talking about benign tumours?
Because they are still tumours, and they need the same careful scanning, timing and teamwork as other tumours. Some treatments used in NF2, such as radiotherapy and certain drugs, come from cancer care. The genetics team also explains inherited results for many tumour conditions, benign or not.
Can the faulty gene be repaired?
No. A gene fault present from birth cannot be corrected or reversed with current medicine. What can be changed is how early tumours are found and how carefully treatment is timed. Research into gene-based treatments is ongoing, but nothing is ready for routine use.
Does SMARCB1 also cause cancer in children?
A different kind of SMARCB1 fault can cause rhabdoid tumours, a rare and aggressive childhood cancer. The faults linked with schwannomatosis are usually milder changes. Your report and counsellor will make clear which type your family has, because the plans are very different.
Why did my tumour report mention NF2 when my blood showed LZTR1?
That fits how schwannomatosis works. The inherited LZTR1 fault is the first step, and the tumour then picks up changes in NF2 as well. Seeing both is expected. Your counsellor can explain how the two results fit together.
Is this the same as the mutation test for cancer treatment?
No. Tests on a tumour to choose a cancer drug look for changes inside the tumour only. The tests described here look for faults you were born with. Tumour testing is explained on our targeted therapy pages, and the two should not be confused.
Can diet or lifestyle change the risk?
No diet or lifestyle change is known to stop these tumours forming. Staying generally healthy helps you cope with scans and any treatment. Be wary of anyone selling supplements for NF2, as none has good evidence behind it.
How common are these conditions?
They are rare. NF2 is uncommon, and schwannomatosis is rarer still. That rarity is the main reason care works best with teams who see these families regularly. It is also why many people wait a long time before anyone connects their symptoms.
Should my whole family be tested now?
Not all at once. Testing starts with the person who has tumours, to find the exact fault. Relatives are then offered a test in a sensible order, with counselling first. Your counsellor will help you plan who to approach and when.
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 — NF2 gene
- MedlinePlus Genetics — Schwannomatosis
- GeneReviews (NCBI Bookshelf) — NF2-Related Schwannomatosis
- National Institute of Neurological Disorders and Stroke — Neurofibromatosis
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
NF2 and schwannomatosis genes: which cancers and what riskWhich tumours each gene is linked withSchwannomatosis vs NF2Telling the two conditions apartPositive for NF2, SMARCB1 or LZTR1: what happens nextThe first steps after a positive resultSMARCA4 and SMARCB1: what the genes doThe other SMARCB1 condition, seen in young children
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