RESUMEN
Reverse transcription-polymerase chain reaction (RT-PCR) was used to study 34 patients with chronic myelogenous leukemia (CML) associated with negative Philadelphia (Ph) chromosome. This report showed evidence of a chimeric BCR/ABL transcript in 18 (52.9%) and 28 (82.4%) cases by first PCR and seminested PCR, respectively. In these BCR/ABL transcript positive cases, the incidence of BCR exon3/ABL exon2 (B3A2) and BCR exon 2/ABL exon2 rearrangement was 25 (89.3%) and 3 (10.7%) cases, respectively. The other 6 Ph negative patients showed no evidence of reciprocal translocation of BCR to chromosome 9. This data demonstrates that seminested PCR is sufficiently sensitive to detect BCR/ABL fusion transcript in Ph chromosome negative CML patients.