Medical Oncologist
CION Cancer Clinics
Testing the family for STK11: who, when and why children come early | CION Cancer Clinics
Once an STK11 fault is found, each parent, brother, sister and child has a one in two chance of carrying it. Unlike most cancer genes, children are usually tested young, because polyps can cause problems in childhood. This page explains who to test first, when to test children, what happens if the fault is new in the family, 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 STK11?
- Which relatives, and what each one stands to learn
- How does testing a relative actually work?
- The terms that come up when a family is tested
- What each result means for the relative tested
- Four things families say when STK11 is found
- What this page cannot tell you
- Common questions about testing the family for STK11
The short answer
Who in the family should be tested for STK11?
Start with the person who has the confirmed fault. Once the exact change is known, their parents, brothers, sisters and children can each be offered a test for that one change. Each has a one in two chance of carrying it. Boys and girls inherit it equally, and either parent can pass it on.
Why children are tested earlier than usual
For most cancer genes, testing waits until a child is an adult and can decide. STK11 is an exception. Polyps in the small bowel can bleed or cause a blockage in childhood, so scope checks usually begin before the teenage years. A child who tests negative is spared those checks completely, which is often the biggest relief of the whole process.
Why looking for freckles is not enough
The dark spots on the lips and inside the mouth are a strong clue, but they vary. Some carriers have very faint spots, and many fade with age. A blood test gives a clear answer where the family's eyes cannot.
A relative who tests negative for the known family fault has the same risk as anyone else and needs no extra checks for it.Relative by relative
Which relatives, and what each one stands to learn
Each relative is being tested for a slightly different reason. Knowing which is theirs makes the conversation easier.
Parents
Testing parents shows which side the fault came from. That tells you which aunts, uncles and cousins to approach next. If both parents test negative, the fault is probably new in you.
What it answers
- Which side of the family to follow
- Whether a parent needs checks too
- Whether brothers and sisters are at risk
Brothers and sisters
Each has a one in two chance if a parent carries it. A sibling who had a childhood bowel blockage, or who has lip spots, is very likely a carrier. Testing confirms it and puts them on the right checks.
Children
Offered testing in childhood, timed with when checks would start. The counsellor talks with parents first, and later with the child in words that suit their age.
The wider family
Aunts, uncles and cousins on the carrier's side come next. Each branch is followed outward, one generation at a time, until the fault stops appearing.
Not sure whether this applies to you?
Ask an oncologistStep by step
How does testing a relative actually work?
Share the original report
The relative's laboratory needs the exact change. A clear copy of the first person's report, or a letter from their counsellor, is essential.
Counselling comes first
The relative meets a counsellor, talks through what a positive result would mean, and decides for themselves. Nobody should be tested only because the family insists.
One blood sample
Only the known change is checked. This is quicker and cheaper than the first person's full test.
Results in person
Results are given at a follow-up appointment, in Telugu if preferred, with a plan ready in case the answer is positive.
A plan for anyone who is positive
A carrier is referred for a first scope. Adults are added to breast, pancreas and gynaecology checks as their age requires.
Words you will hear
The terms that come up when a family is tested
- Index case
- The first person in the family found to carry the fault. Everyone else is tested for their change.
- Cascade testing
- Offering testing to relatives step by step, moving outward from the index case.
- Single-site test
- A test that looks only for the family's known change. Also called a targeted variant test.
- De novo
- A fault that appears for the first time in one person and was not inherited from either parent.
- Mosaicism
- A fault present in only some of a parent's cells. It is rare, but it explains how two children can inherit a fault their parent's blood test did not show.
- Obligate carrier
- A relative who must carry the fault because it appears both above and below them in the family tree.
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Side by side
What each result means for the relative tested
Relative tests positive
Relative tests negative
Offered the same checks as the first person
Returns to routine screening for their age
Their children now have a one in two chance
Their children are not at risk from this fault
Scopes start in childhood if they are young
No scopes are needed for this reason
Breast and pancreas checks follow in adult life
Nothing extra is planned for them
Commonly believed
Four things families say when STK11 is found
"Only the girls need testing, because it causes breast cancer."
Boys and men inherit it just as often. They carry their own bowel, pancreas and testicular risks, and a father can pass the fault to a daughter.
"Let us wait until after her marriage to test."
Waiting can leave a young carrier without scopes at the age they help most. Worries about marriage are real, and a counsellor can talk through who needs to know. The timing of the test should follow the child's health.
"Our parents tested negative, so my brothers are safe."
If the fault is new in you, siblings are very unlikely to carry it. A small chance remains that a parent carries it in some egg or sperm cells only, so siblings are sometimes still offered a test.
"My son has no spots on his lips, so he cannot have it."
Spots vary, can be faint and often fade. Only a test for the family's exact change gives a clear answer.
Being straight with you
What this page cannot tell you
It cannot tell you which of your relatives carry the fault, or exactly when your child should be tested. That depends on your family tree, your child's age and health, and what a gastroenterologist advises. What your specific variant means is a question for the counsellor who ordered the test.
It cannot do the telling for you
Telling relatives is hard, especially in a large family or when some live in another state or abroad. A counsellor can prepare a family letter you can forward, in Telugu or English. India has no specific law that protects people from genetic discrimination in insurance, so raise cover questions with your counsellor before a relative is tested.
Who this does not apply to
If the first person's report shows a variant of uncertain significance, relatives should not be tested for it. A family whose only link to STK11 is a line on a lung tumour report, with no polyps or lip spots in anyone, does not need family testing either.
If you are unsure whether your relatives should be tested, call the helpline and describe the family. Someone will tell you honestly what makes sense.Questions we are asked
Common questions about testing the family for STK11
At what age should a child be tested?
Usually before scope checks would begin, which for this syndrome means late childhood. A child with tummy pain, bleeding or lip spots may be tested sooner. The exact timing is agreed between you, your counsellor and a paediatric gastroenterologist who knows the condition.
Can a newborn baby be tested?
It is possible, but there is rarely any hurry. Checks do not start in infancy, so many families wait until nearer the age scopes begin. Some parents prefer to know early. Both choices are reasonable, and the counsellor will help you weigh them.
Is a relative's test cheaper than the first one?
Yes. A test for one known change costs much less than the full gene panel the first person had. Prices vary between laboratories, so ask for a written quote. Our cost page for STK11 testing in Hyderabad explains what drives the price.
What if the relative with the syndrome has died?
A stored tissue block from an old operation can sometimes be tested. If not, a living relative with polyps or lip spots can have the full test instead. Once their result is known, everyone else can be tested for that change.
Can we avoid passing it to a future child?
Options exist, including testing embryos made through IVF and testing during pregnancy. They are personal choices, and some families do not want them. They are best discussed with a counsellor before a pregnancy begins, not after.
Does a relative have to travel to Hyderabad?
Not always. Many laboratories accept a sample collected closer to home, and some counselling can happen by phone or video. The helpline can tell you what is practical from your district before anyone makes the journey.
What if a relative does not want to know?
That is their right. Share the family letter, explain that the offer stays open, and let them decide in their own time. For a parent deciding on behalf of a young child, the counsellor can talk through the medical reasons for testing in childhood.
Will the rest of the family see my result?
No. Your result belongs to you. Your counsellor will not share it with relatives without your permission. What is shared is the family change, so others can choose to be tested, and that is usually done through you.
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) — Peutz-Jeghers Syndrome
- MedlinePlus Genetics — Peutz-Jeghers syndrome
- National Cancer Institute — Genetic Testing for Inherited Cancer Susceptibility Syndromes
- NCCN — Genetic/Familial High-Risk Assessment: Colorectal, Endometrial, and Gastric
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
STK11 testing cost in HyderabadWhat the known-fault test costs a relativeSurveillance for STK11 carriersThe checks a relative who tests positive would haveSTK11 positive: what happens nextThe first steps after your own positive resultWhich syndromes do require childhood testingWhy STK11 is one of the exceptions
Talk to us
Need help explaining an STK11 result to your family?
A genetic counsellor can prepare a family letter and talk relatives through what testing would mean for them, in Telugu if they prefer. One helpline serves every CION centre.