EP300-ZNF384 fusion is a rare recurrent cytogenetic abnormality associated with B cell acute lymphoblastic leukemia (B-ALL), which was rarely studied in Chinese patient cohort. Here, we used a customized RNA fusion gene panel to investigate gene fusions in 56 selected acute leukemia patients without conventional genetic abnormalities. Two EP300-ZNF384 fusion forms were detected in ten cases, which were in-frame fusions of EP300 exon 6 fused with exon 3 or 2 of ZNF384. The fusions led to the lack of most functional domains of EP300. We firstly reported EP300-ZNF384 fusion in a mixed-phenotype acute leukemia (MPAL) patient whose CD33 and CD13 were negative. The rest nine B-ALL patients with EP300-ZNF384 fusion expressed CD33 and/or CD13. Fifty-six percent of B-ALL patients (5/9) with EP300-ZNF384 fusion were positive with CD10. After the diagnosis of EP300-ZNF384 fusion, 70% of the patients achieved remission after chemotherapy. Our observations indicated that EP300-ZNF384 fusion consists of a distinct subgroup of B-ALL with a characteristic immunophenotype. These patients are sensitive to current chemotherapy regimen and have an excellent outcome.

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