AML with t(8;21)(q22;q22), (AML1/ETO)

Definition

Acute myelogenous leukemia (AML) with t(8;21)(q22;q22) is an acute myelogenous leukemia generally showing maturation in the neutrophil lineage. The protein encoded by this gene is a putative zinc finger transcription factor and oncoprotein. In acute myeloid leukemia, especially in the M2 subtype, the t(8;21)(q22;q22) translocation is one of the most frequent karyotypic abnormalities. The translocation produces a chimeric gene made up of the 5'-region of the RUNX1 gene fused to the 3'-region of this gene. The chimeric protein is thought to associate with the nuclear corepressor/histone deacetylase complex to block hematopoietic differentiation. Several transcript variants encoding multiple isoforms have been found for this gene.^[1]

Sample Cases

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Epidemiology

Acute myelogenous leukemia (AML) with t(8;21)(q22;q22) is one of the most common structural aberrations in AML and can be found in 5-12% of cases of AML and in one third of karyotypically abnormal cases of AML with maturation. It occurs predominantly in younger patients.

Possible causes

Morphology

AML with t(8;21)(q22;q22) most often display the morphology of acute myeloid leukemia (AML-M2). Blasts are generally large with variable numbers of azurophillic granules and Auer rods.

Immunophenotyping

These cases are phenotypically positive for pan-myeloid markers (CD13, CD33) and blast markers (CD34 and CD117), and characteristically for CD19 and CD56. Occasionally cases may show lack of surface pan-myeloid antigens. Besides the frequent coexpression of CD19/CD56, AML with t(8;21) demonstrates a higher incidence of CD34, TdT and lower levels of CD13/CD33 expression.  

Other relevant tests

Sub-classification

Flow Diagnosis

References

1. Ferrara F, Del Vecchio L (2002). "Acute myeloid leukemia with t(8;21)/AML1/ETO: a distinct biological and clinical entity.". Haematologica 87 (3): 306-19. PMID 11869944.
2. Erickson PF, Dessev G, Lasher RS, et al. (1996). "ETO and AML1 phosphoproteins are expressed in CD34+ hematopoietic progenitors: implications for t(8;21) leukemogenesis and monitoring residual disease.". Blood 88 (5): 1813-23. PMID 8781439.