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CION Cancer Clinics
BLM, WRN and RECQL4: what these repair genes do | CION Cancer Clinics
BLM, WRN and RECQL4 are three related genes that help untangle DNA so it can be copied and repaired. When a child inherits a faulty copy from both parents, one of three rare syndromes can follow, each with its own pattern of cancer. This page explains what the genes do, how the three conditions differ, and why carrying one faulty copy is a different matter. 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 do the BLM, WRN and RECQL4 genes actually do?
- Which condition goes with which gene?
- How does a faulty helicase lead to cancer?
- The words you will meet, in plain language
- Carrier or syndrome: what is the difference?
- What this page cannot tell you
- Four things families tell us, and what is actually true
- Common questions about BLM, WRN and RECQL4
The short answer
What do the BLM, WRN and RECQL4 genes actually do?
All three genes make proteins that untangle DNA so it can be copied and repaired safely. When both copies of one of these genes are faulty, DNA breaks and rearranges far more often than it should, and cancer can start at a young age.
A family of three related genes
BLM, WRN and RECQL4 belong to one family of repair genes called the RecQ helicases. A helicase is a protein that unzips the two strands of DNA. Each gene has its own job, which is why a fault in each one causes a different condition with a different pattern of cancer.
Why two faulty copies matter
These are recessive conditions. A person usually needs a faulty copy from each parent before the syndrome appears. Someone with one faulty copy and one working copy is called a carrier, which means they carry the fault but are usually healthy themselves.
Carrying one faulty copy is very different from having the syndrome. Most of this page is about people with two.One gene, one condition
Which condition goes with which gene?
Each gene is linked to a named syndrome. They are all rare, and doctors usually recognise the condition before any gene test is done.
BLM and Bloom syndrome
Children are small from birth and often develop a red rash on the face after sun exposure. Cancers of many kinds can appear in childhood and early adult life.
Often looks like
- Short stature from birth
- Sun-sensitive rash on the cheeks
- Frequent chest and ear infections
WRN and Werner syndrome
Childhood is usually normal. Signs of early ageing appear in young adult life, such as greying hair, cataracts and thin skin. Certain sarcomas, thyroid cancer and melanoma are more common.
RECQL4 and Rothmund-Thomson syndrome
A patchy rash on the cheeks appears in infancy. Some children have bone and skeletal differences. The cancer most linked to it is osteosarcoma, a tumour of the bone.
Why the label matters
Knowing the exact syndrome changes which cancers are watched for and how any cancer is treated. Some of these conditions make the body more sensitive to radiation and certain chemotherapy.
Not sure whether this applies to you?
Ask an oncologistFrom gene to cancer
How does a faulty helicase lead to cancer?
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DNA has to be unzipped every time a cell divides
Before a cell splits in two, it copies all of its DNA. Helicases open the double strand so the copying machinery can read it.
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Repair also needs the strands opened
When DNA is damaged by sunlight, ordinary wear or copying mistakes, the cell has to open the strand to fix it. The RecQ helicases help with this.
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Without a working helicase, errors pile up
In a person with two faulty copies, breaks and swaps between chromosomes happen far more often. The cells carry many more mistakes than usual.
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Some of those mistakes hit growth genes
When an error lands in a gene that controls growth, a cell can start to divide unchecked. With so many errors, this happens earlier in life.
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Which is why cancers appear young and in several places
The pattern differs by gene. Bloom syndrome can bring many cancer types. Rothmund-Thomson mainly affects bone. Werner syndrome shows up in adult life.
On your report
The words you will meet, in plain language
- Helicase
- A protein that unzips DNA so it can be copied or repaired. BLM, WRN and RECQL4 each make one.
- Recessive
- The condition appears only when both copies of the gene are faulty, one from each parent.
- Carrier
- A person with one faulty copy and one working copy. Carriers are usually healthy and have no syndrome.
- Biallelic
- Both copies of a gene are faulty. This is what the report will say when the syndrome is confirmed.
- Pathogenic variant
- A spelling change in the gene known to break it. People often call this a gene fault or a mutation.
- Consanguinity
- Marriage between blood relatives. It makes it more likely that both parents carry the same rare fault.
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Side by side
Carrier or syndrome: what is the difference?
One faulty copy (carrier)
Two faulty copies (syndrome)
Usually healthy, with no visible signs
Signs such as a rash, small size or early ageing
Cancer risk close to usual, evidence still being gathered
Substantially raised cancer risk, often at a young age
Standard screening for age, unless advised otherwise
A tailored watch plan from a specialist team
Matters mostly for the choice of partner
Matters for treatment, screening and family
Being straight with you
What this page cannot tell you
It cannot tell you what a specific variant on your report means. What your specific variant means is a question for the counsellor who ordered the test. The same gene name can describe a harmless change or a serious one.
The evidence on carriers is thin
These syndromes are rare, so studies are small. Some research has asked whether carriers of one BLM fault have a slightly raised risk of bowel cancer. The results do not agree, and there is no settled advice for carriers beyond ordinary screening.
Who this does not apply to
Most people do not need this test. If nobody in the family has the physical signs described above, and there is no unusual pattern of cancer in children or young adults, these genes are very unlikely to be your question. Somatic faults found only inside a tumour are a different matter, covered under targeted therapy.
If your family has a history of marriage between relatives and a child with these signs, ask for a genetics referral. A counsellor can explain it in Telugu.Commonly believed
Four things families tell us, and what is actually true
"Both of us are healthy, so our child cannot have it."
Carriers are usually completely well. Two healthy parents who each carry one fault can have a child with the syndrome. That is exactly how recessive conditions appear.
"Being a carrier means I will get cancer."
A single faulty copy usually leaves a working copy to do the job. Carriers are not considered to have the syndrome, and most live ordinary lives.
"The rash is just a skin problem."
In Bloom and Rothmund-Thomson syndromes, the facial rash can be the first visible clue. A dermatologist who spots it may be the one who suggests a genetic test.
"Cancer treatment will be the same as for anyone else."
Not always. People with some of these syndromes can react more strongly to radiation and certain chemotherapy. The treating team needs to know about the diagnosis before planning treatment.
Questions we are asked
Common questions about BLM, WRN and RECQL4
Are BLM, WRN and RECQL4 the same condition?
No. They are three related genes that do similar jobs in DNA repair. Faults in each one cause a different syndrome, with different physical signs, a different age of onset and a different pattern of cancer. They are grouped together because the proteins belong to one family.
How is the condition passed on?
It is recessive. A child is affected only if both parents pass on a faulty copy. When both parents are carriers, each pregnancy has a one in four chance of an affected child, a one in two chance of a carrier child and a one in four chance of neither.
Does marriage between relatives make it more likely?
Yes. Relatives share more of their genes, so both partners are more likely to carry the same rare fault. This is common and accepted in many Telangana families. It is not a reason for blame, but it is worth mentioning to the genetics team.
Can a carrier be tested?
Yes. Once the exact fault is known in an affected family member, relatives can be tested for that specific change. This is usually done to help with decisions about marriage or pregnancy, rather than because carriers need screening themselves.
Which cancers are linked to each gene?
Bloom syndrome is linked to many types, including leukaemia, lymphoma and bowel cancer at young ages. Werner syndrome is linked to certain sarcomas, thyroid cancer and melanoma. Rothmund-Thomson syndrome from RECQL4 is mostly linked to osteosarcoma, a bone tumour.
Is there a treatment that fixes the gene?
No. A gene fault cannot be corrected or reversed. Care focuses on watching for cancer early, avoiding needless X-rays where possible, protecting skin from the sun, and adjusting cancer treatment when it is needed.
Is this the same as tumour testing?
No. This page is about faults present from birth in every cell. Tests on a tumour look for changes inside the cancer only, and they are used to choose targeted drugs. If a tumour test mentions one of these genes, a germline test may be needed to check.
Where do I start if I think this affects my family?
Write down who has the physical signs, who had cancer and at roughly what age. Take that list to a genetic counsellor or a paediatrician. Call the CION helpline if you are unsure who to see, and someone will point you to the right clinic.
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) — Bloom Syndrome
- GeneReviews (NCBI) — Werner Syndrome
- GeneReviews (NCBI) — Rothmund-Thomson Syndrome
- MedlinePlus Genetics — BLM gene
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
BLM, WRN and RECQL4: which cancers and what riskThe cancer pattern for each gene, set out plainlyBloom syndrome and cancer riskThe BLM condition in more depthTesting the family for BLM, WRN and RECQL4Who else should be tested and whyConsanguinity and cancer riskWhy marriage between relatives matters for recessive genes
Talk to us
Worried a rare syndrome runs in your family?
Tell us about the signs and the cancers in your family. We will help you reach a genetics team who can explain what testing would and would not show. One helpline serves every CION centre.