Schematic localization of primers. Forward primers hybridizing in exon 13 of the BCR gene are symbolized by arrows pointing to the right and reverse primers spanning the intron 1 of gene ABL1 are symbolized by arrows pointing to the left. Colors of arrows for each gene illustrate two-rounds of multiplex LR-PCR. LR-PCR products were obtained in 25/48 cases from the first round PCR using 1 forward primer (red color) localized in BCR exon 13 and 10 reverse primers (red color) spanning the whole ABL1 intron 1 . LR-PCR products were obtained in the remaining 23/48 cases from the second round PCR with 1 forward primer (blue color) hybridizing to sequence of BCR exon 13 and 20 reverse primers (blue colors) hybridizing to ABL1 intron 1 [7,10].