Thrombocytopenia 5

Any thrombocytopenia in which the cause of the disease is a mutation in the ETV6 gene that impair transcriptional repression and megakaryocyte maturation. It is characterized by lifelong thrombocytopenia, mild mucocutaneous bleeding, and variable red cell macrocytosis. Affected individuals have a significantly increased susceptibility to hematologic malignancies, including B‑cell ALL, myelodysplastic syndrome, CMML, and mixed‑phenotype acute leukemia, with onset ranging from childhood to adulthood. Functional studies show that pathogenic ETV6 variants disrupt DNA binding, alter nuclear localization, and exert dominant‑negative effects on hematopoiesis, providing a mechanistic basis for both the platelet phenotype and cancer predisposition.