Complex variant 15;17 translocations in acute promyelocytic leukemia. A case report and review of three-way translocations.

Complex variant 15;17 translocations are increasingly recognized in acute promyelocytic leukemia (APL). We report a novel three-way translocation in APL involving chromosomes 15, 17, and X in the form of t(X;17;15)(q13;q12;q21). Southern blot analysis showed retinoic acid receptor alpha (RARA) gene rearrangement at intron 2. Clinical and morphologic findings are typical of APL, and a complete remission was attained with a course of conventional chemotherapy. A review of three-way complex variants of 15;17 translocation in the literature reveals 21 published cases in addition to ours. PML/RARA fusion was observed in all 8 cases in which molecular genetic analysis had been performed. More cases need to be analyzed to determine if clustering to particular chromosomal bands occurs in variant translocations, and whether APL cases harboring complex 15;17 variants differ clinically from those with classical 15;17 translocation.