Medical Oncologist
CION Cancer Clinics
Testing the family for FH: who, when and how | CION Cancer Clinics
Once one person in a family is found to carry an FH fault, their blood relatives can have a simple, targeted test for that exact change. Parents, brothers, sisters and children come first, and children are usually tested from around the age of eight to ten. This page explains who to offer testing to, how it works, 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 for FH?
- What does testing mean for each relative?
- How does a relative actually get tested?
- What do the words used in family testing mean?
- What does each result mean for a relative?
- What this page cannot tell you
- Four things families believe about testing, and what is true
- Common questions about testing the family for FH
The short answer
Who in the family should be tested for FH?
Start with the closest blood relatives of the person who tested positive: parents, brothers, sisters and children. Each has a one in two chance of carrying the same fault. If a parent tests positive, that parent's own brothers and sisters are offered testing next. The test then moves outward through the family, one branch at a time.
Why the test is simpler for relatives
The first person in a family usually has a broad test of the whole gene, or of a panel of genes. Relatives do not need that. The laboratory already knows exactly which change to look for, so their test checks that one spot. It is quicker to report and usually costs less.
Why it is worth doing
A relative who tests positive can start yearly kidney scans and catch a tumour early. A relative who tests negative can stop worrying and skip scans they never needed. Both answers are useful, and the second is often the more common.
Testing is always a choice. Nobody should be pressured into it, including by other family members.Relative by relative
What does testing mean for each relative?
Each group has its own questions. A counsellor can help you think through all of them.
Parents
One parent almost always carries the fault. Testing both tells you which side of the family to follow. If neither parent carries it, the fault may have started with you, which is uncommon but does happen.
Brothers and sisters
Each has a one in two chance. Brothers matter as much as sisters, because the kidney risk is the same and they can pass the fault on to their own children.
Children
Each child has a one in two chance. FH is one of the few adult cancer conditions where testing is usually offered in childhood, because kidney scans begin young.
Usually
- Offered from around eight to ten
- Timed with the first kidney scan
- Explained to the child in words they understand
Partners
A partner cannot inherit your fault. But if you are planning children, and especially in a marriage between relatives, testing your partner shows whether a child could inherit two faulty copies.
Not sure whether this applies to you?
Ask an oncologistHow it works
How does a relative actually get tested?
Share the result
The first carrier gives relatives a copy of their report, or a family letter from the counsellor. The exact variant name is what the laboratory needs.
See a counsellor
Each relative has their own counselling appointment before testing. It covers what a result would mean for them, for insurance and for their own children.
Give a blood or saliva sample
The laboratory checks only for the family's known change. Relatives living in the districts can often give the sample locally and have it sent on.
Receive the result in person
A positive result leads to a surveillance plan. A negative result usually means no extra checks at all.
Words you will hear
What do the words used in family testing mean?
- Index case
- The first person in the family found to carry the fault. Every other relative's test depends on their report.
- Cascade testing
- Offering testing outward through a family, one branch at a time, starting with the closest relatives.
- Targeted test
- A test for one known change only, rather than the whole gene. Also called familial variant testing.
- First-degree relative
- A parent, brother, sister or child. Each shares half your genes.
- Predictive test
- A test in someone who is well, to see whether they carry a fault already found in the family.
- De novo
- A fault that appeared for the first time in one person, not inherited from either parent. Uncommon in FH.
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Side by side
What does each result mean for a relative?
Tests positive
Tests negative
Yearly kidney MRI, for life
No extra kidney scans needed
Women add a yearly gynaecology review
Fibroids, if any, are treated as for anyone
Their own children are offered testing
Their children cannot inherit the family fault from them
They join the same plan as the first carrier
Their risk returns to that of the general population
Being straight with you
What this page cannot tell you
It cannot tell you whether a particular relative carries the fault. Only their own test can. It also cannot tell you how your family will react, which is often the hardest part. A counsellor can help you plan those conversations and choose the words.
When family testing does not work this way
If the first result was a variant of uncertain significance, relatives are not usually tested for it, because the answer would not mean anything clear. If only a tumour was tested, a blood test in the person with cancer comes first. Tumour testing is handled with our targeted therapy team.
Who this does not apply to
Relatives by marriage cannot inherit the fault, although a partner may be tested for family planning. Families with no confirmed FH carrier should start with a counsellor, not a targeted test, because there is nothing yet to look for.
Commonly believed
Four things families believe about testing, and what is true
"Only the women need testing, because of the fibroids."
Men carry the same kidney risk and pass the fault on in exactly the same way. Testing only the women leaves half the family unprotected.
"My brother looks healthy, so he cannot carry it."
Carriers usually look and feel completely well. Skin bumps may be faint or absent. Only the test can tell.
"Even if I test negative, my children still need testing."
Not for this fault. If you do not carry the family's change, you cannot pass it on. Your children need testing only if their other parent's side raises a question of its own.
"We should test everyone at once, including the babies."
Adults can be tested whenever they choose. Young children are usually tested closer to when kidney scans would begin, so there is time for them to understand and be part of the decision.
Questions we are asked
Common questions about testing the family for FH
My parent has died. Can we still find out which side it came from?
Often, yes. Testing the living parent shows whether the fault came from their side. If that result is negative, it most likely came from the parent who died. A stored tissue block from an old operation can occasionally be tested as well.
How long does a targeted test take?
It is usually quicker than the first person's test, because only one spot is checked. Your counsellor will give you a realistic timeline for the laboratory they use. Ask how you will receive the result, and prefer an appointment to a text message.
Does the family test cost less?
Usually, because it checks one known change rather than a whole gene. The exact price depends on the laboratory. Some laboratories offer family testing at a reduced rate for a period after the first result, so it is worth asking before you book.
Should relatives worry about insurance?
It is a fair question. India has no specific law on genetic results in insurance, and insurers may ask about known conditions. Relatives should read their policy wording and talk to the counsellor before testing, not afterwards, because the timing can matter.
What if a relative does not want to know?
That is their right. You can give them the family letter and leave the decision with them. Some people come back to it years later, often when they are planning a family. A counsellor can talk to a reluctant relative without pressure.
My relatives live abroad. Can they be tested there?
Yes. They need a copy of your report showing the exact variant, which any genetics service can use. The test and the surveillance plan are broadly the same in most countries, though schedules can differ slightly between them.
Does it matter that we are a consanguineous family?
It can. If both partners carry an FH fault, each pregnancy has a one in four chance of a child with fumarase deficiency, a severe illness from infancy. In marriages between relatives both partners are more likely to carry the same fault, so testing both is worth discussing.
Where do we start as a family?
Start with the carrier's report and a family tree listing who had kidney cancer, early fibroids or skin bumps. Take both to a genetic counsellor. Call the CION helpline if you are unsure how to arrange testing for relatives in different towns, and someone will help.
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) — FH Tumor Predisposition Syndrome
- MedlinePlus Genetics — Hereditary leiomyomatosis and renal cell cancer
- NHS — Predictive genetic tests for cancer risk genes
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
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
FH positive: what happens nextWhat a relative who tests positive does nextSurveillance for FH carriersThe checks a positive relative will startThe FH gene: what it does and why it mattersHow the fault is passed on, explained simplyFH mutation: which cancers and what riskWhat a relative's result could mean for their health
Talk to us
Need help arranging tests for your relatives?
Share the carrier's report and tell us where your relatives live. We will help you arrange counselling and targeted testing for each of them. One helpline serves every CION centre.