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CION Cancer Clinics
Positive for SMARCA4 or SMARCB1: what happens next | CION Cancer Clinics
What happens after a positive SMARCB1 or SMARCA4 result depends on who carries the fault. A child already being treated usually keeps the same treatment plan, and the family is offered testing. A well child who carries the fault starts close checks in early childhood. A parent who carries it mainly needs the result for their children. This page walks through each path. 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 happens after a positive SMARCB1 or SMARCA4 result?
- What should the family expect after the result?
- What does a checking plan for a carrier child usually involve?
- The words you will hear, in plain language
- What does a positive result change, and what does it not?
- What this page cannot tell you
- What parents often fear after a positive result
- Common questions after a positive result
The short answer
What happens after a positive SMARCB1 or SMARCA4 result?
The first step is a results appointment with a genetic counsellor. What follows depends on who carries the fault: a child being treated, a well child, or a parent. Each of those paths is different, and none of them has to be worked out alone.
If your child is already being treated
Treatment for the tumour usually carries on as planned. The result adds two new jobs. The team keeps watch for a second tumour elsewhere in the body, and the rest of the family is offered testing.
If a well child carries the fault
Regular checks start straight away, because tumours in this condition mostly appear in the first years of life. A paediatric oncologist plans them and explains what each scan is looking for.
If you are the parent who carries it
Many parents who carry the fault have never been ill and may never be. The result matters most for your children and for future pregnancies. A woman who carries a SMARCA4 fault also has a rare ovarian cancer to discuss with her counsellor.
A positive result is a reason to plan, not a reason to panic. Take the first appointment with the report in hand.The first few weeks
What should the family expect after the result?
Four things usually happen in the weeks after a positive result. They do not all happen at once, and the counsellor sets the order.
A results appointment
The counsellor explains which gene is involved, what kind of change was found, and what it does and does not mean for your child. Bring the written report and a list of questions.
Testing both parents
Both parents are usually offered a blood test for the exact fault. The answer tells you whether it was inherited or arose new in the child. Either answer is useful.
Testing brothers and sisters
Young siblings are usually offered a test early, even if both parents test negative. A parent can carry the fault in some egg or sperm cells without it showing in their blood.
Bring to the appointment
- The child's genetic report
- Each sibling's date of birth
- Any scans or reports they already have
Planning future pregnancies
If you hope to have more children, the counsellor explains the testing options before or during a pregnancy. There is no right answer. The choice stays with the family.
Not sure whether this applies to you?
Ask an oncologistFor a carrier child
What does a checking plan for a carrier child usually involve?
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Checks start in infancy
Tumours in this condition mostly appear in babies and toddlers. So checks begin as soon as a carrier child is identified, not when symptoms appear.
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A brain MRI
This looks for a tumour in the brain. It uses a magnet, not radiation. A young child usually needs sedation to stay still, which a paediatric team arranges safely.
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A tummy ultrasound
This looks at the kidneys and the rest of the abdomen. It is quick, needs no needle and uses no radiation, so it can be repeated as often as the plan needs.
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Scans every few months at first
In the early years, scans are usually repeated every few months. This follows expert agreement rather than large trials, because the condition is rare.
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Less often as the child grows
The risk falls as a child gets older, so checks usually become less frequent. Your team will tell you when and why the plan changes.
In the appointment
The words you will hear, in plain language
- Carrier
- Someone who has the inherited fault but no tumour. A carrier is not a patient and needs checks, not treatment.
- De novo
- New in this child. The fault arose in the egg, the sperm or early in the pregnancy, and neither parent carries it in their blood.
- Germline mosaicism
- A parent carries the fault in some egg or sperm cells only. It is why siblings are tested even when parents are negative.
- Surveillance
- Planned checks in a well child, to find a tumour early. It does not stop a tumour from forming.
- Sedation
- Medicine that helps a young child sleep through a scan. It is given and watched by a paediatric team.
- Preimplantation genetic testing
- Testing embryos made through IVF before one is placed in the womb, so an embryo without the fault can be chosen.
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Side by side
What does a positive result change, and what does it not?
The result changes
The result does not change
Brothers and sisters can be tested for the exact fault
The child's current treatment, in most cases
A carrier child starts regular scans
The fact that many carriers never develop a tumour
Future pregnancies can be planned with testing
Your right to decide what is right for your family
A woman with SMARCA4 has ovarian choices to discuss
A well parent's day-to-day life
Being straight with you
What this page cannot tell you
It cannot set your child's checks. How often scans happen, and when they stop, depends on which gene is involved, your child's age and what has already been found. What your specific variant means is a question for the counsellor who ordered the test.
It cannot promise what the checks will achieve
The checking plans are based on expert agreement and small studies. Nobody has large trials for a condition this rare. Scans can find a tumour earlier, but nobody can promise they always will.
Who this does not apply to
If the SMARCB1 or SMARCA4 change was found only in the tumour, and a blood test was negative, the family usually needs no checks at all. Adults with a SMARCA4 change on a lung tumour report are in a different situation, covered under targeted therapy. Adults with a milder SMARCB1 change linked to nerve tumours follow a separate plan.
Commonly believed
What parents often fear after a positive result
"Our child's treatment has to change now."
In most cases it does not. The tumour is treated on its own merits. The result mainly shapes the follow-up afterwards and what is offered to the rest of the family.
"If I carry it, I will get a tumour too."
Many adult carriers never develop a tumour. The risk is highest in early childhood. Women with SMARCA4 are the exception to discuss, because of the rare ovarian cancer.
"The scans will stop a tumour from happening."
Scans do not prevent anything. They look for a tumour while it is small, which can give the team more options. Keeping every appointment is what makes them useful.
"We should not have any more children."
That is a family's own decision, and no doctor should make it for you. Testing during pregnancy and testing of IVF embryos are both options. A counsellor explains each one without pressure.
Questions we are asked
Common questions after a positive result
Does my child's treatment change because of this result?
Usually not. The treatment is planned on the tumour itself. The result can shape long-term follow-up, including watching for a second tumour, and it may inform some decisions in a very young child. Ask the treating oncologist directly.
How often will a carrier child be scanned?
In the early years, usually every few months, with brain MRI and a tummy ultrasound. The gap widens as the child grows and the risk falls. Your paediatric oncologist will give you a written plan with the dates.
Does every MRI need sedation?
A baby or toddler usually needs sedation to lie still for an MRI. Older children can often manage without it, with preparation and a parent nearby. The team will tell you about fasting before each sedated scan.
What signs should we watch for between scans?
Tell the team promptly about repeated vomiting, especially in the morning, headaches, unsteady walking, unusual sleepiness, a swelling in the tummy or blood in the urine. Do not wait for the next scan.
Can the scans be done closer to home?
Sometimes. A tummy ultrasound can often be done in a district centre. A sedated brain MRI in a young child needs a paediatric team. Keep all reports with the same oncologist so they can be compared over time.
What should a woman carrying SMARCA4 do?
Talk to a counsellor and a gynaecological oncologist about the rare ovarian cancer linked to this gene. Scans have not been shown to find it reliably, so some women consider removing the ovaries once their family is complete. It is one option among several.
Can we avoid passing this on in a future pregnancy?
There are options. Embryos made through IVF can be tested before one is placed in the womb, or a pregnancy can be tested early on. Each option has costs and limits, so see the counsellor before you plan.
Who do we speak to next?
A genetic counsellor for the result, and a paediatric oncologist for the checks. Call the CION helpline if you are not sure where to start, and someone will point you to the right clinic.
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)
Medical Oncologist
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Sources
- GeneReviews (NCBI) — Rhabdoid Tumor Predisposition Syndrome
- National Cancer Institute — Childhood Central Nervous System Atypical Teratoid/Rhabdoid Tumor Treatment (PDQ) – Patient Version
- MedlinePlus Genetics — SMARCB1 gene
- MedlinePlus Genetics — SMARCA4 gene
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
Testing the family for SMARCA4 and SMARCB1Who else should be tested, and in what orderRhabdoid tumour predisposition syndromeThe condition behind the result, explained in fullSMARCA4 and SMARCB1: which cancers and what riskWhich tumours are linked to each geneSMARCA4 and small cell carcinoma of the ovaryThe ovarian question for women who carry SMARCA4
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Tell us who was tested and what the report says. We will help you find the right counsellor and paediatric oncologist for the next step. One helpline serves every CION centre.