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Maternal imprinting in SDHD: why the father's side matters | CION Cancer Clinics
An SDHD fault inherited from your father carries a real chance of tumours. The same fault inherited from your mother rarely causes any. This is called a parent-of-origin effect, or maternal imprinting, and it makes SDHD look as if it skips generations. This page explains what it means for you, for your children and for how your family plans testing. 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
- Why does it matter which parent passed on an SDHD fault?
- What does it mean for you, depending on who passed it on?
- How can SDHD seem to skip a generation?
- The words you will meet, in plain language
- Father's side and mother's side, compared
- Four things families tell us, and what is actually true
- What this page cannot tell you
- Common questions about SDHD and imprinting
The short answer
Why does it matter which parent passed on an SDHD fault?
With SDHD, the parent you inherited the fault from changes your own risk. If it came from your father, you have a real chance of developing tumours and screening is advised. If it came from your mother, tumours are very rare, although you can still pass the fault on.
The chance of passing it on does not change
Whichever parent you are, each child has a one in two chance of inheriting the fault. What changes is whether the child who inherits it is likely to develop a tumour. That depends on whether it reached them through their father or through their mother.
SDHAF2 follows the same pattern
The same father-side pattern has been seen with SDHAF2, a much rarer gene in the same family. The other SDH genes, SDHA, SDHB and SDHC, do not behave this way. With those, a fault from either parent carries the same risk.
Doctors call this a parent-of-origin effect. Older reports and many websites call it maternal imprinting.Where you stand
What does it mean for you, depending on who passed it on?
Find the card that describes you. Your counsellor will confirm it against your own family tree.
You inherited it from your father
You have a raised chance of paragangliomas, most often in the head and neck, and sometimes more than one. Regular screening is advised, usually starting in childhood.
You inherited it from your mother
Your own chance of a tumour is very low. A small number of tumours have been reported in this group, so most teams still discuss whether some checking makes sense for you.
You are a woman who carries it
A child who inherits the fault from you is at low risk themselves. But a son who inherits it can pass it to his own children, and they are then at risk.
Worth doing anyway
- Tell your brothers and sisters
- Keep the result for your children
You are a man who carries it
A child who inherits it from you is at risk, whether or not you have ever had a tumour yourself. Your children are usually offered testing, and screening if they test positive, from childhood.
Not sure whether this applies to you?
Ask an oncologistOne family, four generations
How can SDHD seem to skip a generation?
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A grandfather develops a neck tumour
Testing shows an SDHD fault. He got it from his own father, so his risk was real, and the tumour is found and removed.
-
His daughter inherits the fault
It came from her father, so she has the same father-side risk. She is offered screening, and it matters for her own health.
-
Her son inherits it from her
This time it came through his mother. His own risk is very low, and he may never have a tumour or a symptom in his life.
-
His daughter inherits it from him
Now the fault has come from a father again, so her risk is back. The illness reappears two generations after the grandfather.
-
Why families miss it
From the outside the fault seems to vanish and return. Genes do not skip. What skips is the illness, which is why a full family tree on both sides matters so much here.
On your report
The words you will meet, in plain language
- Imprinting
- A natural process in which some genes work only on the copy from one parent. The other copy is switched off.
- Parent-of-origin effect
- When the effect of a gene fault depends on which parent passed it down. SDHD is the best-known example among cancer genes.
- Paternal and maternal
- From the father and from the mother. A report may say paternally inherited or maternally inherited.
- Obligate carrier
- Someone who must carry the fault because of where they sit in the family tree, even if they were never tested.
- Penetrance
- How often a fault actually leads to a tumour among everyone who carries it. For SDHD it is very different depending on the parent.
- Chromosome 11
- The chromosome that carries the SDHD gene, along with some nearby genes whose activity depends on which parent they came from.
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Side by side
Father's side and mother's side, compared
Inherited from the father
Inherited from the mother
A real chance of tumours
Tumours are very rare
Screening is usually advised
Any checking is decided case by case
A one in two chance of passing it to each child
The same one in two chance
Relatives should be told
Relatives should still be told
Commonly believed
Four things families tell us, and what is actually true
"It came from my mother, so the test was pointless."
Your own risk may be very low, but the result still matters. If you are a man, any child who inherits it from you is at risk, and your brothers and sisters need to know too.
"My father never had a tumour, so it cannot have come from him."
A father can carry SDHD all his life without being ill, for example if he got it from his own mother. His children who inherit it still have the father-side risk.
"Imprinting means the mother's copy of SDHD is switched off."
That was the first explanation. Later research found SDHD itself is usually active on both copies. The favoured idea now involves nearby genes on the same chromosome. The exact reason is still being studied, but the pattern in families is well established.
"Sons are at more risk than daughters, or the other way round."
Your own sex does not change your risk. What matters is the sex of the parent you inherited it from. A brother and sister who both got it from their father share the same risk.
Being straight with you
What this page cannot tell you
It cannot tell you which parent your fault came from. Sometimes that is obvious from the family tree. Sometimes it needs a parent to be tested, or careful work on who else carries it. A genetic counsellor does that work with you.
It cannot promise a mother-side carrier zero risk
Tumours after inheritance from the mother are very rare, but they have been reported. Nobody can honestly say the risk is nil. What your specific variant and your family's pattern mean is a question for the counsellor who ordered the test, and the screening plan that follows is theirs to set.
Who this does not apply to
This pattern belongs to SDHD and SDHAF2. If your family's fault is in SDHA, SDHB or SDHC, the parent it came from makes no real difference to your risk, and this page does not apply to you. It also does not apply to tumour-only results, which describe changes inside the tumour and are covered under targeted therapy.
If you are unsure which parent your fault came from, bring both sides of the family tree to your counselling appointment.Questions we are asked
Common questions about SDHD and imprinting
I inherited SDHD from my mother. Do I need screening?
Guidelines differ. Some teams suggest a single baseline check and then a lighter schedule. Others prefer to follow you more closely because rare tumours have been reported. Your counsellor will explain what they recommend for you, and why, after looking at your whole family.
How do we find out which parent it came from?
The simplest way is to test both parents for the family's exact fault. If only one parent is available and tests negative, the fault almost certainly came from the other. The family tree can also point clearly to one side.
My father has died. Can we still work it out?
Often, yes. If your mother tests negative, the fault most likely came from your father. A stored tissue block from an old operation can sometimes be tested too. Your counsellor will tell you which route is realistic for your family.
I am a woman carrier. Should my children be tested?
Usually yes, though the reason is different. A child who inherits it from you is at low risk themselves. But a son who carries it can pass it to his children with the full father-side risk, so knowing his result protects the next generation.
Does this apply to SDHB?
No. SDHB, SDHC and SDHA faults carry the same risk whichever parent they came from. Only SDHD and the rare SDHAF2 show this father-side pattern. If your report names SDHB, read about that gene separately, because its risks are different.
Can a mother-side carrier ever develop a tumour?
It is very rare, but a small number of cases have been described. That is why most teams do not simply discharge these carriers. Report new symptoms such as a neck lump, a whooshing sound in one ear or bursts of headache and sweating.
Should this affect marriage decisions?
That is a personal decision, and many families worry about it. A counsellor can explain calmly what the result means for future children, including how different it is for a man and a woman carrier. What you share and when is your choice.
Can this be explained to my parents in Telugu?
Yes. The father-side pattern is easier to follow when it is drawn out on your own family tree, in your own language. Ask for counselling in Telugu when you book, and bring older relatives who remember who was ill on each side.
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
- GeneReviews (NCBI) — Hereditary Paraganglioma-Pheochromocytoma Syndromes
- MedlinePlus Genetics — SDHD gene
- MedlinePlus Genetics — What are genomic imprinting and uniparental disomy?
- MedlinePlus Genetics — Hereditary paraganglioma-pheochromocytoma
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
Hereditary paraganglioma and phaeochromocytoma explainedWhat the tumours are and where they growTesting the family for SDH gene faultsWho to test, in what order, and when children are testedSurveillance for SDH gene carriersThe checks a father-side carrier is usually offeredObligate carriersWhy someone can carry a fault without ever being tested
Talk to us
Not sure which side of the family your SDHD fault came from?
Tell us what you know about both sides of the family and who has been tested. We will help you arrange counselling that works out what it means for you and your children. One helpline serves every CION centre.