A rare t(4;12)(q12;p13) in an adolescent patient with acute myeloid leukemia

Acute myeloid leukemia with t(4;12)(q12;p13): an aggressive disease with frequent involvement of PDGFRA and ETV6

We describe the clinical, morphologic, immunophenotypic and molecular genetic features of 15 cases of acute myeloid leukemia (AML) with t(4;12)(q12;p13). There were 9 men and 6 women, with a median age of 50 years (range, 17–76). Most patients had hypercellular bone marrow with a median blast count of 58% and multilineage dysplasia. Flow cytometry analysis showed myeloid lineage with blasts positive for CD13, CD33, CD34, CD38, CD117 and HLA-DR. Interestingly, aberrant CD7 expression was detected in 12/14 cases, and myeloperoxidase was either negative (3/15) or positive in only a small subset of the blasts (12/15). t(4;12)(q12;p13) was detected at time of initial diagnosis in 4 and at relapse or progression in 9 patients. The initial karyotype was unknown in 2 cases. FISH analysis showed PDGFRA-ETV6 rearrangement in all 7 cases assessed. FLT3 ITD was detected in 2/11 cases and IDH2 and JAK2 mutation were each detected in 1/2 cases assessed. There were no mutations of KRAS (0/8), NRAS (0/8), CEBPA (0/3), KIT (0/3), NPM1 (0/3) or IDH1 (0/2). All patients received aggressive multiagent chemotherapy; 7 patients additionally received stem cell transplantation. With a median follow-up of 10 months (range, 6–51), 13 patients died of AML, 1 patient had persistent disease, and 1 patient was lost to follow-up. In summary, AML with t(4;12)(q12;p13) is usually associated with myelodysplasia, aberrant CD7 expression, weak of absent myeloperoxidase expression, frequent PDGFRA-ETV6 fusion, and an aggressive clinical course. The molecular findings suggest that there may be a role for tyrosine kinase inhibitors in patient management.

Rare Cytogenetic Abnormalities and Alteration of microRNAs in Acute Myeloid Leukemia and Response to Therapy

Acute myeloid leukemia (AML) is the most common acute leukemia in adults, which is heterogeneous in terms of morphological, cytogenetic and clinical features. Cytogenetic abnormalities, including karyotype aberrations, gene mutations and gene expression abnormalities are the most important diagnostic tools in diagnosis, classification and prognosis in acute myeloid leukemias. Based on World Health Organization (WHO) classification, acute myeloid leukemias can be divided to four groups. Due to the heterogeneous nature of AML and since most therapeutic protocols in AML are based on genetic alterations, gathering further information in the field of rare disorders as well as common cytogenetic abnormalities would be helpful in determining the prognosis and treatment in this group of diseases. Recently, the role of microRNAs (miRNAs) in both normal hematopoiesis and myeloid leukemic cell differentiation in myeloid lineage has been specified. miRNAs can be used instead of genes for AML diagnosis and classification in the future, and can also play a decisive role in the evaluation of relapse as well as response to treatment in the patients. Therefore, their use in clinical trials can affect treatment protocols and play a role in therapeutic strategies for these patients. In this review, we have examined rare cytogenetic abnormalities in different groups of acute myeloid leukemias according to WHO classification, and the role of miRNA expression in classification, diagnosis and response to treatment of these disorders has also been dealt with.