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CION Cancer Clinics
Testing your family for MSH6: who, when and how | CION Cancer Clinics
Once an MSH6 fault is found, the closest adult relatives should be offered a test: parents, brothers, sisters and grown-up children. Each has a one in two chance of carrying it, and they are tested only for the family's exact variant. This page explains who comes first, how family testing works in practice, what each result means, and the situations that need extra care. 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 MSH6?
- The order in which relatives are usually offered testing
- How family testing actually happens
- Family testing terms, in plain language
- What a relative's result means for them
- What this page cannot tell you
- Four things families say about testing relatives
- Common questions about testing the family for MSH6
The short answer
Who in the family should be tested for MSH6?
Start with the closest adult relatives of the person who tested positive: parents, brothers, sisters and grown-up children. Each has a one in two chance of carrying the same fault. They are tested only for the exact variant already found, which is simpler and cheaper than the first test. Wider family follows, one step at a time.
Why the known variant makes it easier
The first person in the family had to be tested across many genes. Relatives do not. The laboratory looks only at the one spot where the family's fault sits. The answer is usually clear: either they carry it, or they do not.
Why the men matter as much as the women
MSH6 passes through fathers as often as through mothers. A brother who is never tested can pass the fault to a daughter, whose womb risk is significant. Families sometimes test only the women. That leaves half the picture missing.
Why it is worth the effort
Family testing is where most of the benefit of a positive result lies. A relative who learns they carry MSH6 can start colonoscopy on time and catch polyps before they become cancer. A relative who tests negative can stop worrying and skip checks they do not need. Either answer is useful.
Testing a relative is always their own choice. Nobody can be tested without their consent.Who comes first
The order in which relatives are usually offered testing
Counsellors work outwards from the person who carries the fault. Each positive result opens the next ring of the family.
Parents
Testing a parent shows which side the fault came from. That tells you which aunts, uncles and cousins need to be approached, and spares the other side. An elderly parent may feel guilty about passing it on. Nobody chooses the genes they pass down, and knowing now protects the next generation.
Brothers and sisters
Each has a one in two chance of carrying the fault. Siblings in their thirties and above benefit most, because screening may already be due. A sister who tests positive can plan her womb care early, and a brother can protect his own children.
Adult children
Each child has a one in two chance. Testing is offered once they are adults and can decide for themselves.
Worth knowing
- Young children are not usually tested
- Screening does not start in childhood
- An adult child may choose to wait
Aunts, uncles and cousins
Once the side of the family is known, relatives on that side are offered testing too. Large Telangana families can mean dozens of people, and it is fine to go step by step.
Not sure whether this applies to you?
Ask an oncologistStep by step
How family testing actually happens
The first carrier shares the report
The exact variant name on the report is what relatives need. A photograph of the page sent on WhatsApp is often enough for another laboratory to design the test.
A family letter goes out
Many clinics give a short letter explaining the result in plain words. Relatives can take it to any genetics clinic, in India or abroad.
Each relative sees a counsellor
Before testing, the counsellor explains what a positive or negative result would mean for that person. Counselling in Telugu can be arranged.
A single-site test is done
A blood or saliva sample is checked for the family's variant only. The result then decides whether screening starts or whether the relative can stand down.
Words you will hear
Family testing terms, in plain language
- Cascade testing
- Offering testing to relatives one ring at a time, starting with the closest, once a fault is found in the family.
- Single-site test
- A test that looks only for the one variant already known in the family. It is quicker and cheaper than a full panel.
- First-degree relative
- A parent, brother, sister or child. They share half their genes with you.
- Index case
- The first person in the family found to carry the fault. Their report is the key to everyone else's test.
- Predictive test
- A test in someone who is well, to see whether they carry the family's fault before any cancer appears.
- True negative
- A negative result for a fault known to be in the family. It means the relative did not inherit it.
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Side by side
What a relative's result means for them
Tests positive
Tests negative
Starts an MSH6 surveillance plan
Returns to ordinary screening for their age
Their own children may be offered testing
Their children cannot have inherited it from them
Women get a gynaecology plan
No extra womb checks are needed
Aspirin and surgery options are discussed
No risk-reducing steps are needed
Being straight with you
What this page cannot tell you
It cannot tell you how to raise this with a particular relative. Every family has its own history, disagreements and silences. A counsellor can help you plan what to say. What a relative's specific result means is a question for the counsellor who ordered their test.
When parents are related by blood
Marriages within the family are common in parts of Telangana. If both parents carry an MSH6 fault, a child can inherit two faulty copies. This causes a rare childhood condition with a very different cancer picture. Couples in this position should see a counsellor early, ideally before pregnancy.
Who this does not apply to
Cascade testing only works when the family's variant is clearly harmful. If the first report shows a variant of uncertain significance, relatives are not usually tested for it. Their screening is then planned from the family history instead. A tumour-only finding is not a family finding, and belongs under targeted therapy.
A relative who does not want to know is making a valid choice. Keep the door open rather than pressing.Commonly believed
Four things families say about testing relatives
"She looks just like her father, so she must have it."
Looks, blood group and temperament say nothing about which copy of MSH6 a person inherited. Only the test can tell.
"Our children should be tested now, while they are small."
MSH6 screening does not start in childhood, so an early result changes nothing medically. Waiting lets the child decide for themselves as an adult.
"If my brother is negative, I must be negative too."
Each sibling's chance is separate, like tossing a coin for each one. One brother's result tells you nothing about yours.
"Testing will spoil our daughter's marriage prospects."
Many families share this fear. A carrier who knows is screened and protected. Whether and when to share it is a personal decision a counsellor can help think through.
Questions we are asked
Common questions about testing the family for MSH6
Does my relative need the full panel test?
Usually not. Once a harmful MSH6 variant is known, relatives need only a single-site test for that variant. It is simpler, cheaper and gives a clearer answer. A full panel is only needed if their own history suggests a different cause.
At what age can my children be tested?
Usually once they are adults and can give their own consent. MSH6 screening starts in adulthood, so there is no medical reason to test earlier. The exception is when both parents may carry a fault, which needs its own counselling.
My relative lives abroad. Can they be tested there?
Yes. Give them a copy of the report and the family letter. Genetics services in the United States, United Kingdom, Gulf and elsewhere can run a single-site test from it. Ask them to share their result back, so the family record stays complete.
Can a negative relative still get these cancers?
Yes, at the same rate as anyone else in the population. A negative result removes the extra MSH6 risk, not the ordinary risk everyone carries. They should follow normal screening advice for their age.
Do I have to tell my relatives?
It is your decision, and no law in India requires it. Many carriers find it easier with a family letter or with a counsellor present. Relatives often say later they were glad to have been told.
Should an MSH6 result be shared before marriage?
There is no single right answer. Some families share it early, others once a match is serious. A counsellor can talk through the options, including what it means for any future children, without judging.
What if my relative who had cancer has died?
Stored tissue from an old operation can sometimes be tested. If not, testing the closest living relatives from that side is the next step. A counsellor can guide which route makes most sense for your family.
Will testing affect my relative's insurance?
India has no dedicated law on genetic discrimination in insurance, and the position has been argued in court rather than settled. Relatives may want to discuss this with their counsellor, and some arrange cover before testing.
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) — Lynch Syndrome
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
- NHS — Predictive genetic tests for cancer risk genes
- MedlinePlus Genetics — Lynch 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
MSH6 positive: what happens nextWhat a relative who tests positive should expectSurveillance for MSH6 carriersThe checks a positive relative will startLiving with Lynch syndrome in a large familyManaging testing across many relativesConstitutional mismatch repair deficiency in childrenWhen both parents carry a fault
Talk to us
Want help telling your family about MSH6?
We can arrange counselling for relatives, in Telugu if preferred, and a single-site test for the family's variant. Nobody will be pressed into testing. One helpline serves every CION centre.