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PubMed This is a summary of 14 peer-reviewed journal articles Updated
Hematology

Biology & Differential Diagnosis

At a Glance

Adult-onset autosomal recessive sideroblastic anemia is supported by ring sideroblasts in bone marrow and inherited changes in both copies of a relevant gene. Doctors also rule out MDS and acquired causes such as alcohol, lead, copper deficiency, excess zinc, medicines, and vitamin B6 deficiency.

The biology of adult-onset autosomal recessive sideroblastic anemia is a story of “traffic jams” inside your cells. While iron may be present, your body cannot efficiently get that iron into the final step of making hemoglobin [1]. This results in a distinctive cellular appearance and a specific set of challenges that your medical team must distinguish from more common conditions.

The Mystery of the Ring Sideroblast

The hallmark of your diagnosis is the ring sideroblast. To find these, a doctor performs a bone marrow biopsy and applies a special stain called Prussian blue [2].

Normally, iron is used inside the mitochondria (the powerhouses of the cell) to create heme, the part of your blood that carries oxygen. In this condition, a genetic defect acts like a roadblock. Iron enters the mitochondria but cannot be processed efficiently, so it piles up [3]. Under the microscope, this excess iron forms a visible “ring” of granules encircling the cell’s nucleus [2][4].

Why the Roadblock Happens

In many autosomal recessive forms of this disease, the “roadblock” happens in specific gene-dependent ways. Two examples include:

  1. Substrate Shortage (SLC25A38): The cell has difficulty moving necessary building blocks (like the amino acid glycine) into the mitochondria to start making heme [1][5].
  2. Processing Errors (GLRX5): The cell has difficulty handling iron-sulfur clusters, which are essential tools the cell uses to process iron [6][7].

Rule-Outs: Why It Isn’t “Something Else”

A critical part of your diagnosis is confirming that your ring sideroblasts are caused by your genes and not by an external or acquired factor. Ring sideroblasts are not specific to this genetic disease; they can appear in several other conditions that your doctor must consider [4][8].

Condition Why it causes Ring Sideroblasts How it is evaluated
MDS-RS A clonal bone-marrow disorder (Myelodysplastic Syndrome) where an acquired mutation (often SF3B1) causes the ring. [9] Bone marrow analysis for “dysplasia” (abnormal cell shapes) and genetic testing for the SF3B1 mutation. (Note: MDS can exist without SF3B1). [10]
Alcohol Use Chronic alcohol use can temporarily interfere with heme production. [11] Detailed patient history and observing if the anemia improves with abstinence. [8]
Lead Poisoning Lead blocks several enzymes needed for heme synthesis. [8] A simple blood lead level test. [4]
Copper Deficiency or Zinc Excess Copper is required for iron transport; excess zinc can cause copper deficiency. [12] Testing blood levels of copper and zinc. [12]
Medications or B6 Deficiency Certain antibiotics (like isoniazid) or severe vitamin deficiencies can block the process. [8] Reviewing your current and past medication list. Do not stop prescribed medications without medical advice. [4]

Confirming the Genetic Diagnosis

Because adult-onset cases can look very similar to Myelodysplastic Syndrome (MDS)—a more common bone marrow disorder in older adults—doctors rely on a combination of clinical history, bone marrow findings, and germline genetic testing to strongly support an inherited diagnosis [13][4].

Unlike MDS, which is caused by “somatic” mutations (mistakes that happen in your blood cells during your lifetime), autosomal recessive sideroblastic anemia is caused by “germline” mutations (inherited from your parents) [13]. To evaluate this, doctors look for:

  • Biallelic mutations: Finding two mutated copies of a relevant gene (one from each parent) strongly points to an inherited disorder [14].
  • Absence of Clonal Markers: Inherited cases usually do not have the acquired mutations (like SF3B1) typically found in MDS, though this alone is not definitive proof [10][13].

It is important to note that genetic testing is highly valuable but not perfect; panels can miss deep-intronic or structural variants, and sometimes the picture remains uncertain. By evaluating external toxins, checking for clonal markers, and running specialized germline tests, your care team pieces together the puzzle to ensure your treatment targets the correct biological cause of your anemia.

Common questions in this guide

What are ring sideroblasts, and how are they detected?
Ring sideroblasts are developing red blood cells with iron granules forming a ring around the nucleus. A bone marrow biopsy with a Prussian blue stain can show them. They support sideroblastic anemia, but they can also occur in MDS, alcohol-related disease, lead poisoning, nutrient problems, and medication-related anemia.
How is inherited sideroblastic anemia different from MDS?
Inherited disease results from gene changes present in the body's cells from birth, while MDS usually results from acquired changes in blood-forming cells. Doctors compare the marrow for abnormal cell development, test for acquired changes such as SF3B1, and use inherited-gene testing. Finding two changes in the same relevant gene supports an inherited cause, but no single test is conclusive.
Which genes may be tested for autosomal recessive sideroblastic anemia?
Testing may include SLC25A38, GLRX5, and other genes linked to inherited sideroblastic anemia. A strong genetic match often involves harmful changes in both copies of a gene, with one copy inherited from each parent. A negative panel does not always exclude the diagnosis because some changes are difficult for standard tests to detect.
What other conditions can cause ring sideroblasts?
Doctors may check for MDS, chronic alcohol use, lead exposure, copper deficiency from excess zinc or other causes, medicines such as isoniazid, and severe vitamin B6 deficiency. Evaluation may include a medical and medication history, blood lead testing, copper and zinc levels, and review of the bone marrow. Do not stop a prescribed medicine without medical advice.
What does an SF3B1 test tell me?
SF3B1 is an acquired gene change often associated with MDS with ring sideroblasts. Finding it may support an MDS diagnosis when the marrow and clinical findings fit, but its absence does not rule out MDS. It should be interpreted alongside the marrow report and inherited-gene testing.
Can genetic testing miss the cause of adult-onset sideroblastic anemia?
Yes. Some testing panels do not detect certain changes deep inside a gene or larger structural changes, so a negative result may not settle the diagnosis. Doctors may combine repeat or expanded testing with the bone marrow findings, family history, exposure review, and nutrient tests.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my bone marrow tested for the SF3B1 mutation or other somatic changes, which are often found in adult-onset acquired anemia (MDS)?
  2. 2.Did my genetic test specifically look for SLC25A38, GLRX5, or other inherited variants, and were two separate mutations found?
  3. 3.Were my copper and zinc levels checked to rule out nutritional causes for these ring sideroblasts?
  4. 4.Based on my bone marrow report, do I have signs of 'dysplasia' in other cell types besides red blood cells?
  5. 5.Does my diagnosis involve a defect in 'heme synthesis' or 'iron-sulfur cluster' handling, and how does that affect my treatment?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (14)
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    Characterization of Human and Yeast Mitochondrial Glycine Carriers with Implications for Heme Biosynthesis and Anemia.

    Lunetti P, Damiano F, De Benedetto G, et al.

    The Journal of biological chemistry 2016; (291(38)):19746-59 doi:10.1074/jbc.M116.736876.

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  2. 2

    Causes and Pathophysiology of Acquired Sideroblastic Anemia.

    Rodriguez-Sevilla JJ, Calvo X, Arenillas L

    Genes 2022; (13(9)) doi:10.3390/genes13091562.

    PMID: 36140729
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    Establishment of a cell model of X-linked sideroblastic anemia using genome editing.

    Kaneko K, Kubota Y, Nomura K, et al.

    Experimental hematology 2018; (65()):57-68.e2 doi:10.1016/j.exphem.2018.06.002.

    PMID: 29908199
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    Understanding Sideroblastic Anemia: An Overview of Genetics, Epidemiology, Pathophysiology and Current Therapeutic Options.

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    Journal of blood medicine 2020; (11()):305-318 doi:10.2147/JBM.S232644.

    PMID: 33061728
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    P2 Receptor Antagonists Rescue Defective Heme Content in an In Vitro SLC25A38-Associated Congenital Sideroblastic Anemia Cell Model.

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    International journal of molecular sciences 2024; (25(24)) doi:10.3390/ijms252413314.

    PMID: 39769087
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    Functional Analysis of GLRX5 Mutants Reveals Distinct Functionalities of GLRX5 Protein.

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    Journal of cellular biochemistry 2016; (117(1)):207-17 doi:10.1002/jcb.25267.

    PMID: 26100117
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    GLRX5 mutations impair heme biosynthetic enzymes ALA synthase 2 and ferrochelatase in Human congenital sideroblastic anemia.

    Daher R, Mansouri A, Martelli A, et al.

    Molecular genetics and metabolism 2019; (128(3)):342-351 doi:10.1016/j.ymgme.2018.12.012.

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    When Ring Sideroblasts on Bone Marrow Smears Are Inconsistent with the Diagnosis of Myelodysplastic Neoplasms.

    Girard S, Genevieve F, Rault E, et al.

    Diagnostics (Basel, Switzerland) 2022; (12(7)) doi:10.3390/diagnostics12071752.

    PMID: 35885655
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    SF3B1 mutation identifies a distinct subset of myelodysplastic syndrome with ring sideroblasts.

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    Blood 2015; (126(2)):233-41 doi:10.1182/blood-2015-03-633537.

    PMID: 25957392
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    Biology of sideroblastic anemia.

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    [Rinsho ketsueki] The Japanese journal of clinical hematology 2017; (58(4)):347-352 doi:10.11406/rinketsu.58.347.

    PMID: 28484165
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    Peripheral Blood and Bone Marrow Findings in Chronic Alcoholics with Special Reference to Acquired Sideroblastic Anemia.

    Mangla G, Garg N, Bansal D, et al.

    Indian journal of hematology & blood transfusion : an official journal of Indian Society of Hematology and Blood Transfusion 2020; (36(3)):559-564 doi:10.1007/s12288-019-01188-5.

    PMID: 32647433
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    Zinc-induced copper deficiency, sideroblastic anemia, and neutropenia: A perplexing facet of zinc excess.

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    Clinical case reports 2020; (8(9)):1666-1671 doi:10.1002/ccr3.2987.

    PMID: 32983473
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    Sideroblastic anemia in children: challenges in diagnosis and management in three cases.

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    Annals of hematology 2025; (104(4)):2537-2543 doi:10.1007/s00277-025-06266-5.

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    A novel frameshift deletion in SLC25A38 and its role in mitochondrial dysfunction: A case study of sideroblastic anemia in a child from Iran.

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    PMID: 41714435

This page is for informational purposes only and does not constitute medical advice. A hematologist, pathologist, or genetic counselor should interpret your bone marrow, exposure history, and genetic testing.

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