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Testing your family after a VHL result | CION Cancer Clinics
When one person in a family is found to carry a VHL fault, their parents, brothers, sisters and children can each be tested for that exact fault. The test is a simple blood sample, it gives a clear yes or no, and it is usually offered to children as well as adults. This page explains who should be tested, in what order, and what each result means for the family. 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 for VHL?
- Why is each relative offered a test?
- How does family testing actually work?
- The words you will meet, in plain language
- What does each result mean for a relative?
- What this page cannot tell you
- Four things families tell us, and what is actually true
- Common questions about testing the family for VHL
The short answer
Who in the family should be tested for VHL?
Every close blood relative of the person with the fault: parents, brothers, sisters and children. Each of them may carry the same fault. Testing them for that one known change gives a clear yes or no, and anyone who tests negative can stop worrying about VHL.
Why children are included
For many inherited cancer genes, testing waits until a child is an adult and can decide for themselves. VHL is different. Eye checks start in the first year of life, so knowing whether a child carries the fault decides whether those checks are needed at all. Guidelines support testing children in VHL families early.
Why the order matters
Testing spreads outward from the person with VHL. If a parent carries the fault, that parent's side of the family is tested next: their brothers, sisters and children. If neither parent carries it, the fault is probably new in the person with VHL, and aunts, uncles and cousins usually do not need testing. Doing it in this order saves money and avoids testing people who were never at risk.
The first person tested should be the one with VHL. Every other test depends on knowing their exact fault.Relative by relative
Why is each relative offered a test?
The reason is slightly different for each branch of the family. So is what a result changes.
Parents
Testing the parents shows which side the fault came from, or whether it is new. That single answer decides which aunts, uncles and cousins need testing, if any. A parent who carries it also needs checks of their own.
Brothers and sisters
If a parent carries the fault, each brother and sister has a one in two chance of carrying it too. Many feel well and have no idea, because early growths cause no symptoms.
Children
Each child of a carrier has a one in two chance of inheriting the fault. They are usually tested young, because checks begin in infancy.
A negative result means
- No eye checks or scans for VHL
- No sedation for childhood MRI
- Nothing to pass on to their own children
Wider family
Once the carrying parent is known, testing moves to their side: their brothers, sisters and their children. The chain continues until each branch reaches someone who tests negative.
Not sure whether this applies to you?
Ask an oncologistStep by step
How does family testing actually work?
Get the exact fault in writing
The report of the person with VHL names the precise variant. Relatives need a copy, because the laboratory tests for that exact change and nothing else.
Counselling for each relative
Each adult has a short counselling session first. They hear what either result would mean, and they are free to decide not to be tested. Parents decide for young children, with the counsellor's help.
A blood sample
The test looks for one known change, so it is simpler and cheaper than the first test. Samples can often be taken closer to home and sent to the laboratory.
The result, explained
Results are given in person or by video, with time for questions. Carriers are referred for checks, and relatives who test negative are told plainly that VHL checks are not needed.
On your report
The words you will meet, in plain language
- Cascade testing
- Testing relatives one branch at a time, starting from the person with the fault and moving outward.
- First-degree relative
- A parent, brother, sister or child. These are the relatives tested first.
- Known familial variant test
- A test that looks only for the exact fault already found in the family. It is quicker and cheaper than reading the whole gene.
- Predictive testing
- Testing someone who is well, to find out whether they carry the family fault before any growth appears.
- De novo
- A fault that appeared for the first time in one person and was not inherited from either parent.
- Mosaicism
- The fault is present in only some of a person's cells. A mosaic parent can test negative in blood and still pass it on.
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Side by side
What does each result mean for a relative?
Relative carries the fault
Relative tests negative
Starts VHL checks, from infancy if young
No VHL checks needed at any age
Each of their children can be tested
Their children cannot inherit it from them
Doctors must know before any operation or pregnancy
Treated like anyone else
Their side of the family may need testing next
Testing stops on that branch
Being straight with you
What this page cannot tell you
It cannot tell any relative whether they carry the fault. Only a test for the family's exact variant can do that. What your specific variant means is a question for the counsellor who ordered the test.
It cannot make anyone take the test
Adults choose for themselves. Some relatives want to know at once, some later, and some never. Sharing the result still matters, because a relative who does not know cannot choose. A counsellor can help you plan how to tell each branch of the family, especially when relatives live across several districts or abroad.
Who this does not apply to
Relatives of someone with a single kidney tumour or one adrenal tumour, and no confirmed VHL fault, do not need VHL family testing. If the person thought to have VHL was never tested, or no fault was found, the plan is different. A counsellor will decide whether relatives need checks based on the family history instead.
If you are unsure who in your family should be tested first, call the helpline and describe what you know.Commonly believed
Four things families tell us, and what is actually true
"I feel fine, so I cannot be carrying it."
Most carriers feel well for years. Early VHL growths in the eye, kidney or adrenal gland usually cause no symptoms at all. That is exactly why testing, not symptoms, decides who needs checks.
"My parent never had VHL, so I cannot have it."
A parent can carry the fault with few or unnoticed signs, or have growths that were never linked to VHL. Occasionally a parent carries it in only some cells. A test answers the question where family memory cannot.
"Testing the children will only frighten them."
Explained gently, most children take it in their stride. A negative result spares a child years of eye checks and scans. A positive one means growths are found while they are small.
"Every aunt, uncle and cousin needs testing too."
Only the side the fault came from. If neither parent carries it, the wider family is usually not at risk. Testing the parents first saves a great deal of unnecessary worry and cost.
Questions we are asked
Common questions about testing the family for VHL
Who should be tested first?
The person with VHL, if they have not been tested already. Their result names the exact fault. After that, parents, brothers, sisters and children are offered the simpler known-fault test, and the counsellor suggests the order that makes sense for your family.
Can the children be tested at the same time as the adults?
Often, yes. Because VHL checks begin in infancy, there is little reason to make children wait. Parents give consent for young children, and the counsellor explains what a result would mean before any sample is taken.
How long does a relative's result take?
A known-fault test is usually quicker than the first test in a family, because the laboratory knows exactly where to look. The laboratory will give you its own timeline when the sample is sent, and your counsellor will book the result appointment.
Do we need to travel to Hyderabad for the test?
Not always. No fasting is needed, and once a counsellor has arranged the test, a blood sample can often be taken at a collection centre nearer home. The counselling and result discussion can sometimes be done by video.
My brother refuses to be tested. What can we do?
Adults have the right to decline. Share the written result with him, explain why it matters for his children, and leave the door open. A counsellor can speak with him directly, which some people find easier than hearing it from family.
What if the relative with VHL has died?
A stored tissue block from past surgery can sometimes be tested. If that is not possible, a living relative with signs of VHL may be tested instead, or relatives may be offered checks based on the family history. Bring any old reports you can find.
Will a family test affect insurance or marriage?
India has no dedicated law on genetic discrimination, and insurers' positions vary. Raise it with the counsellor before testing, not afterwards. Whether to share a result with a future spouse's family is a personal choice, and a counsellor can help you think it through.
Where do we start?
Find the genetic report of the person with VHL and make copies for relatives. Then call the CION helpline. Someone will help you arrange counselling and suggest who should be tested first.
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
Medical Oncologist
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Sources
- GeneReviews (NCBI) — Von Hippel-Lindau Syndrome
- MedlinePlus Genetics — Von Hippel-Lindau syndrome
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
- NHS — Predictive genetic tests for cancer risk genes
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
VHL positive: what happens nextThe first steps for anyone who tests positiveVHL surveillance from childhood onwardsThe checks a child who carries the fault will needVHL testing cost in HyderabadWhat the first test and relatives' tests usually costVHL and family planningOptions for carriers who plan to have children
Talk to us
Not sure who in your family should be tested first?
Bring the genetic report of the person with VHL and a list of close relatives. We will help you plan who to test, in what order, and where samples can be taken. One helpline serves every CION centre.