[Molecular study of Ph1 chromosome negative chronic myelocytic leukemia]

Six cases of Ph1 chromosome negative chronic myelocytic leukemia (CML) were studied. In five cases, the BCR gene configuration was analyzed with a probe covering the major breakpoint cluster region (M-bcr). No M-bcr rearrangement was detected in two cases. On the contrary, the BCR gene was found rearranged in three other patients. The breakpoints of the chromosome 22 were localized within the M-bcr in two cases and in a region upstream the M-bcr in the remaining case. These data suggest that Ph1 negative CML can be divided into two groups according to the BCR gene stattus. The clinical characteristics and pathogenesis of these two groups may be different.