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Hereditary paraganglioma and phaeochromocytoma: what the SDH genes cause | CION Cancer Clinics
Hereditary paraganglioma and phaeochromocytoma is an inherited condition in which a fault in one of the SDH genes raises the chance of rare tumours along the nerves of the head, neck, chest and abdomen. Most of these tumours are not cancer, but some release adrenaline-like hormones and a few can spread. This page explains what the tumours are, how the genes cause them and what a family can do. 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
- What is hereditary paraganglioma and phaeochromocytoma?
- Where in the body do these tumours grow?
- How does a fault in an SDH gene lead to a tumour?
- The words you will meet, in plain language
- How do the five SDH genes differ?
- Four things families tell us, and what is actually true
- What this page cannot tell you
- Common questions about hereditary paraganglioma
The short answer
What is hereditary paraganglioma and phaeochromocytoma?
It is a family condition caused by a fault in one of five genes: SDHA, SDHB, SDHC, SDHD or SDHAF2. People who carry the fault have a raised chance of rare, usually slow-growing tumours that start in nerve-like tissue. Most of these tumours are not cancer, but they still need to be found and treated.
Two names for one kind of tumour
Small clusters of special cells, called paraganglia, sit alongside the nerves from the base of the skull down to the pelvis. A tumour growing in one of these clusters is a paraganglioma. When the same kind of tumour grows inside the adrenal gland, which sits on top of each kidney, it is called a phaeochromocytoma. Doctors often shorten the pair to PPGL.
Why the word hereditary matters here
A larger share of these tumours are linked to an inherited gene fault than almost any other tumour type. That is why guidelines advise a genetic test for every person diagnosed, even when nobody else in the family has been ill. A positive result protects relatives, because they can be tested and watched before anything grows.
A tumour in this family of genes is not automatically a cancer. Most do not spread.Where they appear
Where in the body do these tumours grow?
The place a tumour grows decides what it does, which symptoms it causes and how it is treated.
Head and neck
These grow beside the big artery in the neck, behind the eardrum or at the base of the skull. They rarely release hormones, so they show up as a lump or a pressure problem instead.
Can look like
- A painless lump high in the neck
- A whooshing sound in one ear, in time with the pulse
- A change in the voice or in hearing
Adrenal gland
A phaeochromocytoma usually releases adrenaline and noradrenaline, the hormones the body makes when it is frightened. The hormones arrive in bursts, so symptoms come and go.
Can look like
- Sudden pounding headaches
- Sweating and a racing heart
- High blood pressure in a young person
Chest, abdomen and pelvis
Paragangliomas along the spine and near the large blood vessels often release hormones too. Tumours in these places are the ones most linked with a higher chance of spreading, especially in SDHB carriers.
Other tumours from the same genes
Less often, the same faults cause a stomach tumour called SDH-deficient GIST, an uncommon kind of kidney cancer, or a pituitary tumour. These are rare, but they are part of why screening covers the whole body.
Not sure whether this applies to you?
Ask an oncologistHow a fault becomes a tumour
How does a fault in an SDH gene lead to a tumour?
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The SDH genes build a small engine in every cell
Together they make an enzyme called succinate dehydrogenase. It works inside the mitochondria, the parts of the cell that turn food into energy.
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An inherited fault knocks out one copy from birth
Every cell has two copies of each gene. A carrier is born with one working copy instead of two. One copy is enough, so nothing goes wrong yet.
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The second copy is lost in a single cell
Over a lifetime, the remaining working copy can be damaged in one cell. That cell can no longer run its engine properly.
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A chemical build-up sends a false alarm
A substance called succinate piles up. It tricks the cell into behaving as if it were starved of oxygen, and it switches on growth signals it would normally keep switched off.
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Why paraganglia are the cells that react
Some paraganglia exist to sense oxygen in the blood, so they respond strongly to that false alarm. Even so, many carriers never develop a tumour, which is why a result means risk and not certainty.
On your report
The words you will meet, in plain language
- Paraganglioma
- A tumour of the small nerve-like cell clusters found from the skull to the pelvis, outside the adrenal gland.
- Phaeochromocytoma
- The same kind of tumour, growing inside the adrenal gland.
- Catecholamines
- Adrenaline, noradrenaline and dopamine. These are the hormones some of these tumours release.
- Metanephrines
- What the body breaks those hormones down into. Measuring them in blood or urine is how a hormone-releasing tumour is picked up.
- Functional tumour
- A tumour that releases hormones. A non-functional tumour does not, and is usually found on a scan or as a lump.
- Metastatic
- A tumour that has spread beyond where it started, for example to bone or lymph nodes. Older reports may say malignant.
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Side by side
How do the five SDH genes differ?
Gene
The pattern it most often follows
SDHB
Tumours in the abdomen and chest, and the highest chance of spread in this group
SDHD
Head and neck tumours, often several, mostly when inherited from the father
SDHC
Usually a single head and neck tumour
SDHA
A lower chance of any tumour, and many carriers never develop one
SDHAF2
Very rare, with the same father-side pattern as SDHD
Commonly believed
Four things families tell us, and what is actually true
"Nobody else in our family had this, so it cannot be inherited."
Many people with an SDH fault have no known family history. Carriers often never develop a tumour, and with SDHD the fault can pass silently through a mother. That is why the test is offered to everyone diagnosed.
"The tumour was benign, so the gene result does not matter."
It matters a great deal. A carrier can develop new tumours in other places over the years, and every blood relative may carry the same fault. The result decides who needs screening.
"High blood pressure in a young person is only stress."
Usually it has an ordinary cause. But blood pressure that comes in bursts with headache, sweating and a racing heart is worth mentioning to a doctor, especially in a family with an SDH fault.
"If one parent carries it, every child will too."
Each child has a one in two chance of inheriting the fault, and a one in two chance of not inheriting it. Children who test negative for the family's fault do not need the screening at all.
Being straight with you
What this page cannot tell you
It cannot tell you whether you or your child carries an SDH fault, or which of the five genes is involved. That comes from a test, arranged by a genetic counsellor or clinical geneticist who has drawn your family tree and knows who was diagnosed with what.
It cannot read your report for you
Two people with a fault in the same gene can have quite different outlooks, depending on the exact change and which parent it came from. What your specific variant means is a question for the counsellor who ordered the test. Tumour testing, which looks for changes inside the tumour only, is a separate question covered under targeted therapy.
Who this does not apply to
Most people with high blood pressure do not have one of these tumours. Most small lumps found on the adrenal gland during a scan for something else turn out to be harmless growths of a different kind. This page is for families where a paraganglioma or phaeochromocytoma has been diagnosed, or where an SDH fault is already known.
If a relative has been diagnosed and nobody has mentioned genetic testing, call the helpline and ask how to arrange a referral.Questions we are asked
Common questions about hereditary paraganglioma
Is a paraganglioma a cancer?
Most are not. They are tumours that grow slowly and stay where they started. A smaller number spread to other parts of the body, and that chance is higher with SDHB faults and with tumours in the abdomen. Your team will explain which situation applies after looking at the scans and the tumour itself.
Why is every patient offered a genetic test?
Because an inherited fault is found in a large share of people with these tumours, often with no family history at all. Knowing the gene changes how the patient is followed up for life, and it lets brothers, sisters and children find out whether they need screening.
Which symptoms should make someone ask about this?
Bursts of pounding headache, sweating and a racing heart, especially with high blood pressure in a younger person. A painless lump high in the neck, or a whooshing sound in one ear, is also worth a check. Most people with these symptoms have another cause, but a doctor can arrange simple tests.
Which relatives should be tested first?
Once the fault is found in the person with the tumour, parents, brothers, sisters and children are usually offered a test for that exact change. The counsellor then works outwards through the family from anyone who tests positive.
Do children need to be tested?
Often, yes. Unlike many inherited cancer genes, SDH tumours can appear in childhood, and screening that starts young genuinely helps. Children are usually tested well before adulthood, with the exact age set by the gene involved and by the counsellor who knows your family.
Does it matter which parent passed the fault on?
For SDHD and SDHAF2 it matters a great deal. Tumours develop almost only when the fault came from the father. A child who inherits it from the mother can still pass it on to their own children. For the other SDH genes, either parent's side carries the same risk.
Can these tumours be removed safely?
Most are removed by surgery. A hormone-releasing tumour needs careful preparation first, usually with blood pressure medicines for a short period beforehand, so that the hormones do not surge during the operation. This is planned by a team used to these tumours.
Can I get tested and counselled in Hyderabad?
Yes. Genetic counselling and testing can be arranged through CION, with the sample taken as ordinary blood. Counselling is available in Telugu, and families travelling from districts can ask for appointments to be grouped together to cut down on journeys.
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 — Hereditary paraganglioma-pheochromocytoma
- National Cancer Institute — Pheochromocytoma and Paraganglioma Treatment (PDQ) – Patient Version
- NHS — Phaeochromocytoma
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
What the SDH genes doThe cell engine these five genes build, explained simplyWhy SDHB carries the highest risk of spreadIf your family's fault is in SDHB, read this nextMaternal imprinting in SDHDWhy the father's side matters so much for SDHDSurveillance for SDH gene carriersWhich checks carriers have, and how often
Talk to us
Has someone in your family been diagnosed with one of these tumours?
Tell us who was diagnosed and whether a gene test was ever done. We will explain whether counselling and testing make sense for your family, and arrange it if they do. One helpline serves every CION centre.