Clinical use of the bcr/abl probe test in the evaluation of chronic myeloid leukemia patients.

CML is characterized by a reciprocal translocation between the abl and bcr genes on chromosomes 9 and 22 and is usually diagnosed by the presence of the Philadelphia (Ph1) chromosome.However, the translocation may also occur without the appearance of the Ph1 chromosome. In this study the diagnostic efficiency of the molecular hybridization assay was investigated in 227 patients using a probe specific for the bcr region of the gene. Gene rearrangements were observed in 96% of Ph1-positive cases and in 92% of the patients in whom no Ph1 chromosome could be detected by karyotype analysis. By using peripheral blood the assay is easy to perform and superior in sensitivity. Thus, it is recommended that this assay should be routinely used as anadjunct to classical cytogenetics.