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Ataxia-pancytopenia syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Ataxia-pancytopenia syndrome

Ataxia-pancytopenia syndrome is a rare genetic condition that causes progressive neurological impairment and a shortage of blood cells.

Overview

Ataxia-pancytopenia syndrome affects the cerebellum—the part of the brain that coordinates movement—and the bone marrow. The severity and progression of the condition vary among individuals.

Symptoms

Neurological issues are associated with the loss of tissue (atrophy) in the cerebellum and include:

  • Poor coordination and balance (ataxia)
  • Difficulty judging distance or scale (dysmetria)
  • Uncontrollable muscle contractions (clonus)
  • Involuntary back-and-forth eye movements (nystagmus)

These issues worsen over time, often requiring wheelchair assistance. The syndrome also causes pancytopenia, a shortage of red blood cells, white blood cells, and platelets, which can lead to fatigue, frequent infections, and abnormal bleeding. Affected individuals have an increased risk of blood cancers, such as myelodysplastic syndrome and acute myeloid leukemia.

Causes

The syndrome is caused by "gain-of-function" mutations in the SAMD9L gene. The SAMD9L protein acts as a tumor suppressor, regulating cell growth and division. These mutations increase the protein's ability to block cell growth, leading to a shortage of blood cells in the bone marrow.

Paradoxically, these mutations also increase cancer risk. It appears that bone marrow cells can develop additional genetic changes—such as the loss of the SAMD9L gene or a deletion of part of chromosome 7—to compensate for the overactive protein. While these changes reduce the severity of pancytopenia, they also allow cells to grow uncontrollably, which can lead to cancer.

Inheritance

This condition is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder. In all reported cases, an affected person has had one parent with the condition.

Frequently Asked Questions

Implement strict hand hygiene, avoid crowded places during peak infection seasons, and keep up‑to‑date vaccinations (including annual influenza and pneumococcal vaccines). Use platelet transfusions or antifibrinolytics (e.g., tranexamic acid) for bleeding episodes. Educate caregivers on early signs of infection (fever, chills) and instruct them to seek prompt medical evaluation. Schedule regular hematology visits, and discuss early bone‑marrow biopsy if there is a sudden drop in blood counts or new cytogenetic abnormalities, as these may herald myelodysplastic syndrome or acute myeloid leukemia.
Key distinguishing features include the simultaneous presence of progressive cerebellar ataxia and a documented pancytopenia (low red cells, white cells, and platelets) in the same patient, often with early‑onset cytopenias. Genetic testing revealing a pathogenic gain‑of‑function SAMD9L variant confirms the diagnosis, whereas most other ataxias lack hematologic abnormalities.
HSCT has been used in selected patients with severe marrow failure, but the decision is complex because the underlying SAMD9L gain‑of‑function can persist in non‑hematopoietic tissues, and transplant does not address neurologic decline. Clinical trials of targeted inhibitors of the SAMD9L pathway are ongoing but not yet standard. Management currently focuses on supportive care, infection prophylaxis, and vigilant cancer surveillance.
t diagnosis obtain a complete blood count with differential, reticulocyte count, serum ferritin, vitamin B12, folate, and bone marrow aspirate/biopsy to assess cellularity. Repeat CBC every 3 months, and perform bone‑marrow evaluation annually or sooner if cytopenias worsen. Periodic flow cytometry for dysplastic changes and cytogenetic analysis (especially for monosomy 7 or 7q deletions) are critical for early cancer detection.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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