A novel clonal t(1;4)(p36.1;q31) translocation in acute promyelocytic leukaemia

The majority of patients with acute promyelocytic leukaemia (APL) carry the hallmark t(15;17)(q22;q21) translocation, involving the promyelocytic leukaemia/retinoic acid receptor-α (PML/RARα) fusion gene, and by sensitivity of blast cells to all-trans retinoic acid (ATRA) and/or arsenic trioxide therapy. The incidence and prognostic significance of additional chromosomal abnormalities in APL are still obscure. We reported a patient with APL with PML/RARα and clonal t(1;4)(p36.1;q31) positive, but t(15;17)(q22;q21) negative. She was initially treated with ATRA and idarubicin and got complete remission. Our report supports the suggestion that there are no differences in the clinical outcome between APL cases with classical t(15;17)(q22;q21) and those with additional chromosomal abnormality t(1;4)(p36.1;q31). To our knowledge, this is the first report of a patient with APL without classical t(15;17)(q22;q21), showing an additional clonal t(1;4)(p36.1;q31) and involving PML/RARα fusion gene. It will help us to understand the role of the clonal t(1;4)(p36.1;q31) translocation in the pathogenesis of APL when relevant genes involved in the clonal translocation have been identified.