 Acute promyelocytic leukaemia (APL) is characterized by t(15;17), which results in the formation of two chimaeric genes, PML-RAR alpha and RAR alpha-PML.     ///    "Our results, however, show persistence of t(15;17) cells expressing RAR alpha-PML fusion mRNA in patients in long-term remission of APL. "    ///    Persistence of RAR alpha-PML fusion mRNA detected by reverse transcriptase polymerase chain reaction in patients in long-term remission of acute promyelocytic leukaemia..     ///    PML-RAR alpha transcripts have been detected in all cases of APL whilst those of RAR alpha-PML have been detected in only about 67% of cases.     ///    The level of sensitivity for detecting RAR alpha-PML was some 10-fold higher than that for PML-RAR alpha.     ///    "All patients were negative for PML-RAR alpha, whereas in six patients (remission 3-9 years) RAR alpha-PML was consistently detected. "    ///    "Only one patient at remission showed the 5' breakpoint RAR alpha-PML, with the rest showing the 3' breakpoint 144 bp RAR alpha-PML. "