Background and objectives: Translocations involving the RUNX1 gene on chromosome 21 are commonly encountered in acute myeloid leukaemia (AML) and typically involve the RUNX1T1 (ETO) gene on chromosome 8 or, less commonly, the MECOM gene on chromosome 3¹. We present the first case of a patient diagnosed with an AML with t(1;21)(q21;q22) at our institution.
The patient was a 17-year-old man who presented with a short history of constitutional symptoms. There was no history of previous malignancy or exposure to cytotoxic chemotherapy.
Methods: The investigations performed included a full blood count (FBC), peripheral blood and bone marrow aspirate morphology, cytochemistry and flow cytometry as well as conventional karyotyping and fluorescence-in-situ-hybridisation (FISH).
Results: The FBC showed a mild leucocytosis with a moderate anaemia of 9.9 g/dL and a thrombocytopenia of 53 x109/L. Morphological assessment revealed the presence of 26% blasts with significant dysplasia noted in the granulocytic series. The diagnosis of an AML was confirmed with weak myeloperoxidase positivity demonstrated on cytochemical testing and CD13, CD33 and CD117 positivity noted on flow cytometry. FISH was sent for all the known recurrent genetic abnormalities associated with AML. Testing for t(8;21) was negative but extra copies of the RUNX1 gene was present in ~90% of the cells. Conventional karyotyping revealed the presence of t(1;21)(q21;q22) as well as monosomy 7.
Conclusion: Based on these results the patient fulfilled the 2016 World Health Organization criteria for the diagnosis of AML with myelodysplasia-related changes (monosomy 7). Occasional reports of the t(1;21)(q21;q22) genetic abnormality involving the ZNF687 gene on chromosome 1 has been described in literature but appears to be exceedingly rare ² The patient was started on a cytarabine and daunorubicin regimen but failed to achieve remission and unfortunately demised four months post-diagnosis.
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