Expression pattern of the RAR alpha-PML fusion gene in acute promyelocytic leukemia..     ///    We investigated the organization and expression pattern of the RAR alpha-PML gene in a series of APL patients representative of the molecular heterogeneity of the t(15;17) and found (i) two types of RAR alpha-PML mRNA junctions (RAR alpha exon 2/PML exon 4 or RAR alpha exon 2/PML exon 7) that maintain the RAR alpha and PML longest open reading frames aligned and are the result of chromosome 15 breaking at two different sites.     ///    " Two chimeric genes, PML-RAR alpha and RAR alpha-PML, are formed as a consequence of the acute promyelocytic leukemia (APL)-specific reciprocal translocation of chromosomes 15 and 17 [t(15;17)]. "    ///    and (ii) 10 different RAR alpha-PML fusion transcripts that differ for the assembly of their PML coding exons.     ///    "A RAR alpha-PML transcript was present in most, but not all, APL patients.. "