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CION Cancer Clinics
Wilms tumour gene testing for the family: who, in what order, and why | CION Cancer Clinics
Testing the family starts with the child who had Wilms tumour or has the syndrome. Once their exact change is known, parents and young brothers and sisters can be tested for that one change with a simple blood test. A negative result can spare a sibling months of kidney scans. This page explains who is tested, in what order, and what each result means. 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
- Who in the family should be tested, and why?
- Which relatives are offered a test?
- How does family testing actually happen?
- The words you will meet, in plain language
- What a brother's or sister's result means
- Four things families tell us, and what is actually true
- What this page cannot tell you
- Common questions about testing the family
The short answer
Who in the family should be tested, and why?
The child who had Wilms tumour, or who has the syndrome, is tested first. If a fault is found, parents are usually tested next, then young brothers and sisters. The aim is simple: to find which children need regular kidney scans, and which can safely skip them.
Why start with the affected child
Their result tells the laboratory whether there is a fault at all, and exactly which one. Testing a well brother first, without knowing what to look for, can give a negative result that means very little. Starting in the right place saves money and avoids false comfort.
Why young children come first
Wilms tumour is a cancer of early childhood. A baby or toddler who carries the family fault needs regular ultrasound scans now, while the risk is highest. A child who does not carry it can be spared months of hospital visits. For this reason, testing children is normal in these families, unlike genes that only raise risk in adult life.
A blood test cannot find a Wilms tumour. It finds the fault that raises the chance of one. Scans are what find tumours.Once the fault is known
Which relatives are offered a test?
Testing moves outward from the affected child, one branch at a time, and only as far as the results say it should.
Parents
Testing both parents shows whether the fault was inherited or arose for the first time in the child. Many WT1 faults, and most chromosome 11 switching errors, are new. When neither parent carries it, the chance for brothers and sisters is usually low.
Brothers and sisters
Young siblings come first because their scan schedule, if they need one, should start early. Older siblings still matter. They may carry the fault without ever having had a tumour and could pass it to their own children.
Children of a survivor
Adults who had Wilms tumour and carry a known fault can have their babies tested soon after birth. Planning this during pregnancy means the result is back before scans would need to begin.
The wider family
If a parent carries the fault, that parent's own relatives may carry it too.
Usually offered to
- Aunts and uncles on the carrier's side
- Their young children, first
- For CDKN1C, women on the mother's side especially
Not sure whether this applies to you?
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How does family testing actually happen?
Counselling first
A genetic counsellor draws the family tree, examines the child if needed, and explains what each possible result would mean before any sample is taken.
Testing the affected child
Usually a blood sample. If the doctors suspect a change present in only some cells, a skin sample or stored tumour tissue may be tested as well.
Targeted tests for relatives
Once the exact change is known, each relative is tested for that one change only. This is faster and cheaper than the first test. If a parent's chromosomes are rearranged, a separate chromosome test is used.
A plan with every result
Each result comes with a plan: which children start scans, which do not need them, and who else in the family should be told.
On your report
The words you will meet, in plain language
- Index case
- The first person in the family to be tested, usually the child who had Wilms tumour or the syndrome.
- Cascade testing
- Offering a test to relatives one branch at a time, once the family's fault is known.
- De novo
- A change that appeared for the first time in the child and was not inherited from either parent.
- Mosaic
- A change present in only some of the body's cells. It can make a blood test look normal.
- Imprinting
- Genes switched on or off depending on which parent they came from. It is why CDKN1C usually causes illness only through the mother.
- Balanced rearrangement
- Pieces of two chromosomes swapped in a healthy parent. It can become unbalanced in a child and cause WAGR syndrome.
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Side by side
What a brother's or sister's result means
They carry the family fault
They do not carry it
Regular kidney ultrasound scans through early childhood
No extra scans are needed for Wilms tumour
Kidney function and blood pressure may be checked
Routine child health checks apply
Their own children can be tested later
They cannot pass this fault on
Counselling again when they are old enough to understand
No further genetic follow-up for this fault
Commonly believed
Four things families tell us, and what is actually true
"Both parents are healthy, so it cannot be in the family."
A parent can carry a fault and never have been ill. With CDKN1C, a father can carry it silently and pass it to a daughter, whose own children are then at risk. Testing is the only way to know.
"Our child's fault was new, so nobody else needs to think about it."
Brothers and sisters are usually at low risk, though rarely a parent carries it in some egg or sperm cells only. The affected child's own future children can still inherit it, so it matters again when they grow up.
"Testing children is wrong. We should wait until they can choose."
That is right for genes that only matter in adult life. Wilms tumour risk is highest in the early years, so waiting would mean either missing scans or scanning every child. A test answers the question now.
"If my other child tests negative, the doctors were wrong about the first one."
A negative result in a sibling says only that they did not inherit the fault. It does not change the diagnosis or the plan for the child who does carry it.
Being straight with you
What this page cannot tell you
It cannot tell you which of your relatives carries the fault, or what your family's specific change means. That is a question for the genetic counsellor or clinical geneticist who ordered the first test. They have the full report, the family tree and the examination findings in front of them.
It cannot decide the order for you
Every family is shaped differently. A counsellor may test a grandparent early to confirm which side the fault came from, or skip a branch entirely. Families who travel from districts can often have relatives' samples collected closer to home once the plan is agreed.
Who this does not apply to
If the first test found no inherited fault, testing relatives usually adds nothing. The same is true when the fault was found only in the tumour. Most families of a child with Wilms tumour are in this group. Some worry about what a result means for a daughter's marriage. A counsellor can talk that through privately, and a result belongs to the person tested.
Questions we are asked
Common questions about testing the family
Should my other children be tested?
If a fault was found in the affected child, yes, in most cases, and ideally while they are young. A negative result can spare them regular scans. A positive one makes sure scans start early enough. Your counsellor will say how urgent it is for each child.
What sample is needed from relatives?
Usually a small blood sample, and sometimes saliva. Relatives are tested only for the exact change already found, which is simpler than the first test. A chromosome test may be added if a parent could carry a rearrangement.
Why does it matter whether the mother or father carries CDKN1C?
CDKN1C works mainly from the copy inherited from the mother. A child who inherits the fault from their father is usually unaffected. So the same result can mean different things for different branches, which your counsellor will map out with you.
Can we test a baby before or soon after birth?
Yes. Once the family fault is known, a newborn can be tested soon after birth. Testing during pregnancy is also possible in some situations. Discuss both options with a counsellor early in the pregnancy, not at the end.
My child tested negative. Can scans stop?
If the family's exact fault is known and your child does not carry it, extra Wilms scans are normally not needed. Confirm this with the doctor who planned the scans before stopping. Routine child health checks carry on as usual.
What if the first test found nothing but doctors still suspect a syndrome?
Some changes sit in only part of the body and are missed in blood. Doctors may test skin or tumour tissue, or diagnose the syndrome from its features. Relatives are then advised from the diagnosis and family history rather than a single result.
Will relatives be told without our permission?
No. Results are confidential, and it is usually the family who share them. Counsellors can give you a short letter that explains the finding, which makes the conversation with relatives easier. You decide who hears and when.
How do we arrange testing for relatives who live far away?
Once the family fault is known, a relative's sample can often be collected locally and sent to the same laboratory. Keep a copy of the first report to share. Call the CION helpline if you are not sure where to start.
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
- National Cancer Institute — Wilms Tumor and Other Childhood Kidney Tumors Treatment (PDQ) – Health Professional Version
- GeneReviews (NCBI) — Beckwith-Wiedemann Syndrome
- MedlinePlus Genetics — Wilms tumor
- MedlinePlus Genetics — WAGR syndrome
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
Wilms tumour gene positive: what happens nextThe plan once a child's result comes backAbdominal ultrasound screening in predisposed childrenWhat the scans involve for a sibling who carries the faultSurveillance for Wilms tumour gene carriersThe full schedule of checks, by conditionThe Wilms tumour genes: what they doWT1, CDKN1C and the rest, explained simply
Talk to us
Not sure who in your family should be tested?
Tell us who had Wilms tumour and what testing has been done so far. We will arrange counselling and help you plan testing in the right order. One helpline serves every CION centre.