Medical Oncologist
CION Cancer Clinics
Testing your family for a HOXB13 fault | CION Cancer Clinics
When one person in a family is found to carry a HOXB13 fault, their parents, brothers, sisters and children can be tested for that exact change. The test is simpler than the first one, and a negative result is usually clear. Men gain the most, because the risk is to the prostate. This page explains who to test first, 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 offered a HOXB13 test?
- Which relatives should be tested first?
- How does a family HOXB13 test actually work?
- Family testing words, in plain language
- What does each result mean for a relative?
- What this page cannot tell you
- Four things families tell us about testing relatives
- Common questions about testing relatives for HOXB13
The short answer
Who in the family should be offered a HOXB13 test?
Every close relative of a carrier can be offered a test: parents, brothers, sisters and adult children. Each has an even chance of carrying the same fault. Brothers and adult sons gain the most, because the raised risk is to the prostate and a positive result leads to earlier checks.
Why women are still offered it
A sister's or daughter's own risk is not clearly raised by HOXB13. But if she carries the fault, each of her sons has an even chance of inheriting it too. Her result tells the next generation of men whether they need to think about testing.
Why the test is simpler this time
The first person's test usually searched a panel of genes. A relative's test looks only for the one change already found in the family. That makes it quicker to read and usually cheaper, and the answer is clear: they either have that change or they do not.
The family letter from your counsellor names the exact change. Relatives should take it to their own appointment.Who and in what order
Which relatives should be tested first?
There is no fixed order, but most families start with the men who could act on a result soonest.
Brothers
Often the first to be tested. A brother who carries the fault can start prostate checks straight away. A brother who does not follows the routine advice for his age.
Adult sons
Tested when they are adults and choose to be. Checks for carriers begin in adult life, so there is no need to rush a son in his teenage years.
Parents
Testing a parent shows which side of the family the fault came from. That tells you which uncles and cousins to offer a test next.
If a parent cannot be tested
- Test the other parent instead
- Offer a test to a parent's brother or sister
- Occasionally, use a stored tissue sample
Sisters and daughters
Offered so they know whether their sons might carry the fault. Their own screening follows routine advice either way.
Not sure whether this applies to you?
Ask an oncologistStep by step
How does a family HOXB13 test actually work?
Share the family letter
The first carrier passes on the letter from their counsellor. It names the gene, the exact change and the laboratory that found it.
Counselling before the test
The relative sees a counsellor of their own. They talk through what a positive or negative result would mean, and whether they want to know at all.
A blood or saliva sample
The laboratory checks only for the family's change. It can be done in another city if needed, as long as the laboratory has the letter.
The result session
The counsellor explains the result. A man who carries the fault is referred to plan prostate checks, and his own children can then be offered a test.
Words you will hear
Family testing words, in plain language
- Cascade testing
- Testing relatives step by step, moving outward from the first person found to carry a fault.
- Single-site test
- A test that checks only for the exact change already found in the family.
- True negative
- A negative result when the family's fault is already known. It means the relative did not inherit it.
- Obligate carrier
- A relative who must carry the fault because of how the family tree fits together, such as a parent between two carriers.
- Predictive test
- A test in someone who is well, to see whether they have inherited a raised risk.
- Penetrance
- How often a fault leads to cancer among everyone who carries it. For HOXB13 it is well short of certain.
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Side by side
What does each result mean for a relative?
Positive for the family fault
Negative for the family fault
Carries the same HOXB13 change
Did not inherit it
Men start prostate checks earlier
Men follow routine advice for their age
Their children can be offered a test
Their children cannot inherit it from them
Risk is raised, not certain
Other family history may still count
Being straight with you
What this page cannot tell you
It cannot tell any relative what their own result means. What a specific variant means for one person is a question for the counsellor who ordered their test. Each relative deserves their own counselling session, not a summary passed on by phone.
It cannot decide for your family
Testing is a choice, and some relatives will not want to know. Nobody can be tested without their consent. India has no law requiring you to tell relatives, and no dedicated law on genetic discrimination in insurance. A counsellor can help you think through both before you speak to anyone.
Who this does not apply to
If the first person's result was a variant of uncertain significance, relatives should not be tested for it. Their result would mean nothing either way. And if the relative with prostate cancer tested negative, testing well relatives for HOXB13 usually adds little.
Commonly believed
Four things families tell us about testing relatives
"My sister does not need to know. She cannot get prostate cancer."
Her sons can inherit the fault from her. Telling her lets her decide whether her sons should be offered a test as adults.
"My brother tested negative, so I will be negative too."
Each brother or sister has a separate, even chance. One sibling's result tells you nothing about another's.
"We should test the children now, so we know."
Prostate checks do not start in childhood, so an early result changes nothing for the child. It only takes away their own choice later.
"My father is well, so it must be from my mother's side."
A man can carry HOXB13 all his life without prostate cancer. Only a test, or a careful family tree, shows which side the fault came from.
Questions we are asked
Common questions about testing relatives for HOXB13
Do my relatives need the full gene panel I had?
Usually not. Once the family's change is known, relatives are tested only for that change. If a relative has had cancer themselves, or has a strong history on the other side of the family, their counsellor may suggest a wider test instead.
Can relatives in another city or abroad be tested?
Yes. Any accredited laboratory can look for the family's change, as long as it has the family letter. A counselling session in their own city, by phone or by video, should come before the sample. The result is then shared with their own doctor.
What if a relative does not want to be tested?
That is their decision to make. Share the information once, clearly, and let them know it is there if they change their mind. Nobody can be tested without their consent, and a counsellor can talk to them if they want to understand more.
My father has died. Can we still find which side it came from?
Often, yes. Your mother can be tested, or your father's brothers and sisters. If he had surgery or a biopsy in the past, a stored tissue block can sometimes be tested. Ask the hospital that treated him whether his block is still kept.
How old should my son be before he is tested?
Old enough to decide for himself, as an adult. Prostate checks for carriers begin in adult life, so testing well before then brings no benefit. Many sons choose to test when they start thinking about their own health or their own family.
If my brother tests negative, does he need any checks?
He did not inherit the family's HOXB13 fault, so routine advice for his age applies. If several other men in the family had prostate cancer, his doctor may still take that history into account when deciding when to offer a PSA test.
Will my relatives' tests cost as much as mine?
Usually less, because only one change is checked. Prices vary between laboratories. Ask whether the laboratory that tested you offers family testing, since using the same laboratory also makes the result easier to compare.
How do I tell my family?
Start with the relatives who gain the most, usually brothers and adult sons. Share the family letter rather than explaining from memory. Some families find a joint appointment easier. Call the CION helpline if you need help finding a counsellor, including one who speaks Telugu.
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
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
- MedlinePlus Genetics — HOXB13 gene
- National Cancer Institute — Genetics of Prostate Cancer (PDQ) – Health Professional Version
- 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
Cascade testing: how a result moves through a familyThe general method behind testing relativesSurveillance for HOXB13 carriersWhat a relative who tests positive does nextHOXB13 positive: what happens nextThe first carrier's own next stepsWhy most adult-onset genes are not tested in childhoodWhy your children's test can wait
Talk to us
Want help arranging tests for your relatives?
Tell us who in the family carries the fault and who wants to be tested. We will help each relative find counselling and the right test, wherever they live. One helpline serves every CION centre.