Medical Oncologist
CION Cancer Clinics
Testing your family for a MAX or TMEM127 fault | CION Cancer Clinics
When one person is found to carry a MAX or TMEM127 fault, their parents, brothers, sisters and children can be tested for that exact change. It is a simple blood or saliva test, and the answer is usually a clear yes or no. This page explains who to test first, when to test children, how the test works and what each result means for a relative. 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 MAX or TMEM127?
- Which relatives should be offered a test, and why?
- What actually happens when a relative is tested?
- What do the family testing terms mean?
- What does each result mean for a relative?
- What do families believe about this testing that is not true?
- What can this page not tell you?
- Common questions about testing the family for MAX and TMEM127
The short answer
Who in the family should be tested for MAX or TMEM127?
Every parent, brother, sister and child of someone with a confirmed MAX or TMEM127 fault should be offered a test. Each of them has a one in two chance of carrying the same fault. The test looks only for that exact change, uses a blood or saliva sample, and usually gives a clear yes or no.
Start with the first person's report
Relatives can only be tested for a fault that has already been found. The first step is a copy of the original report, showing the gene and the exact variant. Without it, the laboratory does not know what to look for, and a relative may be sent for a full panel they do not need.
Why testing well relatives matters
A carrier can have a hormone-making tumour for years without knowing. It may show only as high blood pressure, or not at all, until something like an operation or a pregnancy triggers a dangerous surge. Knowing who carries the fault lets checks start before that happens. It also lets everyone who tests negative stop worrying.
Testing on both sides of the family
Early studies suggested MAX tumours appear mainly when the fault comes from the father. The pattern is not firm, so relatives on both sides are still offered testing. Do not leave anyone out because of which parent they are linked through.
Who to ask
Which relatives should be offered a test, and why?
Closest relatives come first. Then testing moves outward along the branch the fault came from.
Parents
Testing both parents shows which side the fault came from. That tells you which aunts, uncles and cousins may be at risk. If neither parent carries it, the fault probably arose new in the person first tested.
Brothers and sisters
If a parent carries the fault, each brother and sister has a one in two chance of carrying it too. Normal blood pressure does not rule it out, because some tumours make little hormone.
Children
Each child of a carrier has a one in two chance. The right age to test a child is agreed with the counsellor. With MAX, where tumours can appear in young adults, it is usually discussed before adulthood. With TMEM127 there is usually less hurry.
A child who tests negative
- Needs no special checks
- Cannot pass the fault on
The wider family
Once the carrier parent is known, their brothers, sisters and cousins are offered testing in turn. Relatives on the other side of the family do not need it.
Spouses and in-laws are not at risk from this fault.Not sure whether this applies to you?
Ask an oncologistHow it works
What actually happens when a relative is tested?
Get the original report
The relative brings a copy of the first report, or a family letter naming the gene and variant. The counsellor checks that the change is classed as pathogenic, meaning known to cause these tumours.
A conversation before the test
A counsellor explains what a positive and a negative result would mean, including for work, marriage and insurance. This can be done in Telugu, and family members can sit in.
One sample, one variant
A blood or saliva sample is tested for that single change only. This is simpler and usually cheaper than the panel test the first person needed.
The result, and what follows
A relative who tests positive starts with a hormone test and a scan to check that no tumour is present now. A relative who tests negative needs no special checks, and neither do their children.
Words you will hear
What do the family testing terms mean?
- Index case
- The first person in the family found to carry the fault. Their report is the key for everyone else.
- Cascade testing
- Offering the test branch by branch, starting with the relatives closest to the index case.
- Predictive test
- A test in someone who is well, to learn whether they carry the family's fault before any tumour appears.
- Single-site test
- A test for one known variant only, instead of reading the whole gene.
- De novo
- A fault that arose new in one person and was not inherited from either parent.
- Parent-of-origin effect
- When a fault behaves differently depending on which parent passed it on. This has been suggested for MAX but is not proven.
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Side by side
What does each result mean for a relative?
Tests positive
Tests negative
A baseline hormone test and scan, then regular checks
No special checks are needed
Each of their children has a one in two chance
Their children are not at risk from this fault
Tells doctors before any operation or pregnancy
Ordinary care before surgery or pregnancy
Their own brothers and sisters are offered a test
Testing stops on this branch
Commonly believed
What do families believe about this testing that is not true?
"My blood pressure is normal, so I cannot be a carrier."
Blood pressure says nothing about whether you inherited the fault. Only the test can tell you that. Some carriers with a tumour have normal readings too.
"It came from my mother's side, so it will not affect us."
The idea that MAX matters only through fathers comes from small early studies. It is not proven, so relatives are offered testing whichever side the fault came from.
"If I test negative, my children still need testing."
A negative result for the family's exact fault means you did not inherit it and cannot pass it on. Your children do not need a test for it.
"We married within the family, so everyone must be at risk."
These faults pass from one carrier parent to a child. Marrying within the family does not change the one in two chance, though the fault can turn up on more than one branch. Your counsellor will trace each branch.
Being straight with you
What can this page not tell you?
It cannot tell you which of your relatives carries the fault, or decide for you when to test a child. Those are conversations for a genetic counsellor who knows your family tree. What your specific variant means is a question for the counsellor who ordered the test.
It cannot make relatives agree
Every adult has the right to decide whether to be tested, and some will say no, at least at first. A family letter lets them act later, in their own time and in their own city. The offer does not expire.
Who this does not apply to
If the person with a tumour had a gene test that found no fault, there is nothing specific for relatives to be tested for. They are guided by the family history instead. A fault found only inside a tumour, and not in the blood, is not inherited, and belongs with our targeted therapy pages.
Questions we are asked
Common questions about testing the family for MAX and TMEM127
At what age should children be tested?
There is no single age. It depends on the gene and on how young relatives were when tumours appeared. For MAX, testing is usually discussed before adulthood so that checks can start in time. For TMEM127, families often wait longer. Your counsellor and endocrinologist will agree the timing with you.
Can relatives in another city be tested there?
Yes. With the family letter and a copy of the original report, a relative can see a counsellor near where they live. Many laboratories also accept saliva kits by courier. Nobody needs to travel to Hyderabad just for the test.
Is a relative's test cheaper than the first test?
Usually. The first person was tested on a panel of several genes, while relatives are tested for one known change. Some laboratories offer a lower family rate if the first test was done with them, so ask before booking.
The person with the tumour has died. Can we still test?
If their genetic report still exists, yes. If not, a stored tissue block from their operation can sometimes be tested. Otherwise a living relative may need the full panel first. A counsellor will work out the best route with you.
Do I have to tell my relatives myself?
Usually the family hears it from you, but you do not have to find the words alone. Your counsellor can write a family letter explaining the fault, the chance of carrying it and how to get tested. Many people share it on WhatsApp.
If I test positive, what should I do first?
Book a hormone blood or urine test and a scan to check that no tumour is present now. Tell any doctor planning surgery, a scan with contrast or a pregnancy about your result. Most carriers with clear baseline tests simply move on to regular checks.
Can the test show which parent passed it on?
Yes, if both parents are tested. Only the carrier parent will test positive. If neither does, the fault most likely arose new, and the parents' other children are at very low risk. Aunts, uncles and cousins then do not need testing.
What if a relative refuses to be tested?
That is their right. Give them the family letter and let them know the offer stays open. Suggest they at least tell their doctor about the family fault before any operation, so that a hormone test can be done 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
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Sources
- GeneReviews (NCBI) — Hereditary Paraganglioma-Pheochromocytoma Syndromes
- MedlinePlus Genetics — Hereditary paraganglioma-pheochromocytoma
- 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
MAX and TMEM127 mutation: which tumours and what riskWhat a relative who tests positive is at risk ofMAX and TMEM127 positive: what happens nextThe first tests and scans for a new carrierMAX and TMEM127: what the genes doHow these genes work, in plain languageHow cascade testing worksHow testing moves through a family, branch by branch
Talk to us
Need help telling your relatives?
Tell us who in the family has been tested and who has not. We can arrange counselling, a family letter and testing for relatives, in Telugu if you prefer. One helpline serves every CION centre.