Myelodysplastic neoplasms
MDS with low blasts and SF3B1 mutation
Also called Myelodysplastic neoplasm with low blasts and SF3B1 mutation
If you or someone you love has just heard this diagnosis, start here. This guide explains what the condition is, how it is usually treated and whether a transplant plays any part.
MDS with low blasts and an SF3B1 mutation is a genetically defined marrow cancer that often causes anemia. Many people receive monitoring and treatment to improve blood production; donor transplantation is considered only in selected circumstances.
Other names and abbreviations
MDS-SF3B1, MDS-RS (older), myelodysplastic syndrome, MDS, refractory anemia with ring sideroblasts, refractory anaemia with ring sideroblasts, MDS with ring sideroblasts/SF3B1 mutation, refractory anaemia with ring sideroblasts (historical)
In short
- This type of MDS is a marrow cancer with a change in the SF3B1 gene and few immature cells. It often causes anemia.
- Some people with mild, stable disease are watched. Others get transfusions or anemia medicines, such as luspatercept, which helps red blood cells mature.
- A donor transplant is not usually the first approach. It may be considered for severe problems that continue despite treatment, or if the disease gets worse.
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Underlined words open a short explanation. See all terms
Where transplant fits
Most people with well-controlled lower-risk disease start with monitoring or anemia treatment. Allogeneic transplantationComing from another person. In an allogeneic, or donor, transplant, the stem cells come from a relative or an unrelated volunteer whose cells are a close enough match to the patient's. is considered for selected severe or progressive disease, not simply because an SF3B1 mutation is present.
Treatment depends on the exact diagnosis, disease stage, prior treatment and the person’s health.
Key facts
- Who it affects
- This subtype mainly affects older adults, although age does not establish or exclude the diagnosis.
- How common
- About 15 in every 100 people with MDS (14.6%)352 of 2,454 people with MDS in an international research dataset (Bernard et al., shared on cBioPortal), reclassified under the 2022 WHO system; published 2025. A research cohort, not a population count. Source: How common
- Cells used in a transplant
- Donated blood-forming cells for allogeneic transplantation. Marrow, peripheral blood or cord blood and donor type are selected for the patient and transplant approach.
- Where a donor fits
- Limited transplant role
The condition
What it is
Myelodysplastic neoplasmsA group of cancers in which the bone marrow does not make enough healthy blood cells and abnormal cells appear in the blood or marrow. Also called myelodysplastic syndromes (MDS). Sometimes they turn into acute myeloid leukemia., also called myelodysplastic syndromes (MDS), are cancers of blood-forming stem cellsYoung cells that can grow into every type of blood cell: red cells that carry oxygen, white cells that fight infection and platelets that help blood clot. They are found in the bone marrow and the bloodstream.. Abnormal development means the marrowThe soft, spongy tissue in the center of most bones. Red bone marrow holds the blood-forming stem cells that make red blood cells, white blood cells and platelets. does not reliably produce enough working blood cells. MDS can cause serious problems without ever progressing to acute myeloidHaving to do with the bone marrow, or with certain blood-forming cells made there. Also called myelogenous. Acute myeloid leukemia (AML) is a fast-growing cancer that starts in these cells. leukemia (AML).
SF3B1 helps cells process genetic messages. A mutation can disrupt blood-cell development and is often associated with ring sideroblasts, developing red cells with a ring of iron around the nucleus. Diagnosis uses the whole pattern of marrow and genetic findings, not the appearance of one cell alone.
Marked as affected: blood stem cells and red blood cells.
- Blood stem cell, Affected, In the bone marrow
- Myeloid line
- Red blood cells, Affected
- Platelets
- Granulocytes
- Monocytes
- Lymphoid line
- B cells
- Plasma cells, Develop from B cells
- T cells
- NK cells, Natural killer cells
- Myeloid line
What causes it
MDS usually develops through acquired genetic changes in blood-forming cells, and the underlying cause is often unknown. Age, previous chemotherapy or radiation, smoking and some chemical exposures can increase risk.
Inherited predisposition can contribute in a minority of patients. Personal and family history may prompt genetic evaluation, which can also affect the suitability of related donors. MDS is not contagious.
Symptoms and effects
Anemia can cause fatigue, breathlessness or difficulty with ordinary activities. Low neutrophilsA type of white blood cell that is one of the first to respond to germs such as bacteria. Low neutrophil levels raise the risk of serious infection. increase infection risk, and low plateletsTiny pieces of cells in the blood that help form clots to slow or stop bleeding. They are made in the bone marrow. Too few platelets can cause easy bruising and bleeding. can cause bruising or bleeding. Some people first learn about MDS through a routine blood test.
Blood counts, marrow findings and molecular tests help track the disease. The subtype name and the overall risk score answer different questions: prognosis depends on the combination of genetic findings, blast countYoung blood cells that have not finished developing. In leukemia and some related diseases, abnormal blasts build up in the marrow and blood and leave less room for healthy blood cells. Doctors count blasts to help identify the disease. and blood-cell shortages, not a single label.
Many cases have a relatively slower course, but the severity of anemia, additional mutations and other changes over time can alter risk. A favorable average prognosis does not make transfusion dependence or fatigue unimportant.
Diagnosis and treatment
How MDS with an SF3B1 mutation is diagnosed
This type of MDS often first shows up as anemia on a routine blood test. The first tests are a complete blood count (CBC) and a blood smear, where cells are checked under a microscope. Blood tests for vitamin B12 and folate help rule out other causes of anemia.
A hematologist (blood doctor) confirms MDS with a bone marrow aspiration and biopsy. The pathologist counts blasts, the immature cells. For this subtype, blasts must be under 5 in every 100 marrow cells and under 2 in every 100 white cells in the blood. The pathologist also looks for ring sideroblasts, young red cells with a ring of iron around the nucleus.
Gene testing finds the SF3B1 change. Under the 2022 WHO rules, the gene result defines this subtype. The change must show up in at least 5 in every 100 copies of the gene the test reads. A set number of ring sideroblasts is no longer required. Chromosome and gene tests also check for findings that rule this subtype out. These include a 5q deletion, loss of chromosome 7 or part of its long arm (7q), three or more chromosome changes, or two damaged copies of TP53. Doctors then use a risk score, such as the IPSS-R or IPSS-M.
Older reports may call this refractory anemia with ring sideroblasts or MDS with ring sideroblasts. The newer name reflects the gene change.
How it is treated
Observation is appropriate for some people with mild, stable disease. Anemia treatment may include transfusions, erythropoiesis-stimulating medicines or luspatercept, which helps later stages of red-cell maturation. Selection depends on prior treatment, transfusion needs, the broader diagnosis and the medicine’s indication.
Response is tracked through symptoms, blood counts and how often transfusions are needed. Treatment may change if it stops working or if the disease develops higher-risk features. In 2024, the FDA approved a medicine called imetelstat for some adults with lower-risk MDS. It is for people who need frequent red-cell transfusions (4 or more units over 8 weeks) and whose anemia has not responded to, no longer responds to, or cannot be treated with red-cell growth medicines (ESAs). In the main trial of 178 people with MDS, about 40 in 100 on imetelstat went at least 8 weeks without a transfusion, compared with 15 in 100 on a placebo. Clinical trialsA research study that tests how well a new medical approach works in people. Trials can test new ways to screen for, prevent, diagnose or treat a disease. are another option.
Allogeneic transplantation is generally not the initial approach for well-controlled lower-risk MDS. It may be considered for severe problems despite treatment or for progression, after weighing disease risk against transplantA treatment that gives a patient healthy blood-forming stem cells through a vein. The cells travel to the bone marrow and replace faulty marrow or marrow damaged by treatment. They can come from the patient or a donor. risk.
Kinds of treatment described for MDS with low blasts and SF3B1 mutation: watching and regular checks (for some people), supportive care, medicines, a donor stem cell transplant (for a few people) and clinical trials.
After diagnosis, the options described here
Watching and regular checks, For some people
Some people with mild, stable disease are watched.
Supportive care
Red-cell transfusions help with anemia.
Medicines
Anemia medicines include red-cell growth medicines and luspatercept, which helps red blood cells mature.
Donor stem cell transplant, For a few people
A donor transplant is not usually the first approach and may be considered for severe problems that continue despite treatment.
Clinical trials
Clinical trials are another option.
These are the kinds of treatment this page describes, not a plan. Which ones fit, in what order and whether they are combined differs from person to person.
When transplant specialists are usually consulted
Transplant is not usually part of first treatment for this subtype. NMDP's consultation timing guidelines recommend HLA typingA lab test that finds a person's tissue type (HLA markers). It starts with a blood draw or a cheek swab. Doctors compare a patient's results with those of relatives, registry donors and cord blood units. and a transplant consultation for people with MDS who have certain features. These include needing regular transfusions, low blood counts that do not improve with treatment, higher-risk chromosome or gene changes, or treatment that has stopped working.
Read the guidanceDaily life and the donor’s role
Living with the condition and treatment
Repeated blood tests, clinic visits and sometimes marrow samples are part of care. Some people need regular transfusions or medicines to support blood production. The practical burden depends on the degree of anemia, infection risk, treatment schedule and other health conditions.
If transplant is considered, discussions include the chance of disease control, treatment-related risks, recovery support and personal goals. A donor search can take place while these decisions and other treatment continue.
The role of a blood stem cell donor
A donor is relevant if allogeneic transplantation becomes the preferred treatment, rather than simply because an SF3B1 mutation has been found. Medicines that improve anemia and ordinary red-cell transfusions are different from receiving a stem cell graftThe blood-forming stem cells given to a patient in a transplant. In a donor transplant, the graft comes from the donor's bone marrow or blood, or from donated cord blood..
When allogeneic transplantation is selected, the graft comes from another person. A matched relative, unrelated registry donor or an appropriate alternative donor may be suitable. HLA compatibilityMarkers on most cells that make up a person's tissue type. Doctors test a patient's and donor's HLA to see how well they match. The more markers they share, the better the chance the body accepts the donor's cells., donor age and availability, patient health and the transplant approach all matter; no donor category is best for every person.
Looking ahead
Looking ahead
Outlook for MDS with an SF3B1 mutation
MDS with an SF3B1 mutation usually has a slower course and a better outlook than many other kinds of MDS. SF3B1 changes are linked to longer survival. These cases seldom pick up the extra gene changes that make MDS more aggressive. For many people, the main challenge is anemia, with the tiredness and transfusionsPutting blood, or parts of blood such as red cells or platelets, into a person's bloodstream through a vein. Some people with blood disorders need regular transfusions. that come with it.
Outlook still differs from person to person. Some other gene changes raise risk. In a large international study, RUNX1 and EZH2 mutations were linked to shorter survival in SF3B1 MDS. Newer anemia medicines, including luspatercept and imetelstat, can free some people from transfusions for a time.
A donor transplant is rarely needed for this subtype. It is usually considered only if serious problems continue despite treatment or the disease gets worse.
About these numbers. Each one says which group of people it comes from, and the place and years where the source gives them. It describes what happened across that group, not what will happen to any one person. And a figure measured among people who had a transplant is not the same as the number of people who need one.
- About 6 years (middle half: 3 to 12 years)Median survival (half of people lived longer)
456 people in the SF3B1 genetic group of an international study of 3,233 people with MDS or related conditions (published 2024); about 60% of this group met the 2022 WHO definition of MDS with SF3B1 mutation
Read the source: Median survival (half of people lived longer) - 38% with luspatercept vs 13% with placeboWent 8+ weeks without a transfusion on luspatercept
229 people with transfusion-dependent lower-risk MDS with ring sideroblasts whose anemia was not helped, or unlikely to be helped, by ESAs (MEDALIST trial), as summarized in a 2026 review
Read the source: Went 8+ weeks without a transfusion on luspatercept
These numbers describe groups of people. They cannot tell any one person how long they will live or how treatment will go.
Common questions
What does an SF3B1 mutation mean in MDS?
SF3B1 is a gene that helps cells edit, or splice, genetic messages before proteins are made. In MDS, the SF3B1 change is acquired in blood-forming cells during life; it is not inherited. It is found in about 30 of every 100 people with MDS. It is the most often changed of the splicing genes in MDS. It is linked to ring sideroblasts, poor red cell production and a slower, more favorable course than many other kinds of MDS.
What is the life expectancy with SF3B1-mutated MDS?
No number can predict one person's future, but this subtype usually has a better outlook than many other kinds of MDS. The outlook section on this page gives survival from a large international study published in 2024. Other gene changes, such as RUNX1 or EZH2 mutations, were linked to shorter survival.
Is MDS with SF3B1 mutation the same as MDS with ring sideroblasts?
They overlap a lot. Older systems named this disease by its ring sideroblasts, young red cells with a ring of iron around the nucleus, as in refractory anemia with ring sideroblasts. The 2022 WHO classification names it by the gene change instead. In one study of people with the older ring sideroblast subtypes, 81% had an SF3B1 mutation. Cases with ring sideroblasts but no SF3B1 mutation tended to do less well.
What is luspatercept, and does it help SF3B1 MDS?
Luspatercept is an anemia medicine given as a shot under the skin every 3 weeks. It blocks certain growth signals (it is a TGF-beta inhibitor). The MEDALIST trial included people with lower-risk MDS with ring sideroblasts who needed transfusions and had not been helped by red-cell-boosting drugs (ESAs). More people went at least 8 weeks without a transfusion with luspatercept than with placebo. The outlook section on this page gives the figures. The FDA approved it for this use in 2020, and it has since been studied as a first treatment.
Can SF3B1 MDS turn into leukemia?
It can, but it is less likely than with many other kinds of MDS. In a study of 293 people with ring sideroblasts, those with an SF3B1 mutation had a lower chance of their disease getting worse than those without one. The authors described the course as indolent, meaning slow. Care teams still check blood counts regularly, because new genetic changes can raise the risk.
For your next appointment
MDS with low blasts and SF3B1 mutation
From the Jada Bascom Foundation disease library, jadabascomfoundation.org. Printed .
Questions to bring to your care team
- What SF3B1 change was found and at what level, and did testing find other changes such as RUNX1 or TP53?
- Would you start with luspatercept or an ESA (such as epoetin), and how will we know if it is working?
- If the first treatment stops working, what would come next?
- Am I building up extra iron from transfusions, and would iron chelation help me?
- What is the exact name of the diagnosis or subtype, and what does it mean for treatment?
- What is the goal of each treatment you are suggesting?
- What would make a transplant worth considering later on?
- Are there clinical trials that might fit?
- Where can our family find support during treatment?
A one-page list to take to the next appointment, with room for notes.
Supporting someone with a diagnosisSupport for patients and families
These independent organizations offer information and support. JBF is not affiliated with them.
- MDS Foundation A global nonprofit offering MDS education, patient guides, patient forums and ways to connect with experts and other patients.Worldwide
- Aplastic Anemia and MDS International Foundation (AAMDSIF) Offers patient guides, a helpline, virtual support groups and a peer support network for people with MDS and related bone marrow diseases.United States
- MDS UK Patient Support Group A UK charity offering free membership, trusted information, online support meetings and one-to-one help for people with MDS or CMML and carers.United Kingdom
Sources and further reading
- Myelodysplastic Syndromes Treatment (PDQ), Health Professional Version
NCI, Accessed 2026-09-05 - Myelodysplastic Neoplasms/Syndromes (MDS)
EBMT Handbook / NCBI Bookshelf, Accessed 2026-09-05 - WHO fifth-edition classification: Myeloid and Histiocytic/Dendritic Neoplasms
WHO classification authors / Leukemia, Accessed 2026-09-05 - REBLOZYL (luspatercept-aamt) prescribing information
FDA, Revised 2026-02; accessed 2026-09-26 - Indications for haematopoietic cell transplantation and CAR-T: 2025 EBMT practice recommendations
EBMT / Bone Marrow Transplantation, Accessed 2026-09-05 - Stem Cell and Bone Marrow Transplants for Cancer
NCI, Accessed 2026-09-05 - Donor and cord blood unit selection guidelines
NMDP / CIBMTR, Accessed 2026-09-05 - FDA approves imetelstat for low- to intermediate-1 risk myelodysplastic syndromes with transfusion-dependent anemia
U.S. Food and Drug Administration, 2024-06-06; accessed 2026-09-26 - Myelodysplastic Syndromes Treatment (PDQ), Patient Version
National Cancer Institute (PDQ), Updated 2024-10-04; accessed 2026-09-26 - Myelodysplastic Syndromes: 2026 Update on Diagnosis, Risk-Stratification and Management
American Journal of Hematology (Garcia-Manero G), 2026 - Molecular taxonomy of myelodysplastic syndromes and its clinical implications
Blood (Bernard E et al.), 2024 - Reclassification of Myelodysplastic Neoplasms According to the 2022 World Health Organization Classification and the 2022 International Consensus Classification Using Open-Source Data: Focus on SF3B1- and TP53-Mutated Myelodysplastic Neoplasms
Annals of Laboratory Medicine, 2025 - SF3B1-mutant MDS as a distinct disease subtype
Blood (Malcovati L et al., International Working Group for the Prognosis of MDS), 2020 - SF3B1 mutation identifies a distinct subset of myelodysplastic syndrome with ring sideroblasts
Blood (Malcovati L et al.), 2015 - Navigating the New Era in Myelodysplastic Neoplasms: A Review of Prognostic Implications of the IPSS-M Score and 2022 WHO Classification
Hematology Reports, 2025 - Consultation timing guidelines: myelodysplastic syndromes (MDS)
NMDP, Accessed 2026-09-26
This information explains a condition and its treatments. It cannot diagnose an illness or recommend treatment for an individual. Your care team can explain how the evidence applies to you. Written and source-checked by the Jada Bascom Foundation. Each page lists the published sources it draws on.
Ways to help
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More in the library
Keep learning
Interactive storyWhy matching is hard: leukemiaHow leukemia affects blood production, when a donor transplant may help, and how inherited HLA markers shape the search for a suitable donor.Begin the storyPart of 2 diagnosis guides, each explaining how its subtypes fit together: Myelodysplastic syndromes (MDS) and Types of blood cancer.
