Chronic myelocytic leukemia (CML) is cytogentically characterized by the Philadelphia chromosome (Ph(1)) resulting from a reciprocal translocation t(9;22)(q34;q11). The breakpoints on chromosome 22 are clustered within a limted region of 5.8 kilobase (kb), termed the breakpoint cluster region (bcr). Herein the bcr rearrangement was examined to clarify the relationship between CML and related diseases. By Southern blot analysis of DNA, the bcr rearrangements were recopnized (bcr(+)) in 52 of 54 standard Ph(1)-positive (Ph(1+)) CML and all 3 variant Ph(1+)CML［46, XX, t(9;22;13)(q34;q11;q22),46, XX, t89;22)(q21;q11) and 46, XX, t(9;22)(q34;q11),inv (9)(9q22;22q13)］. The site of breakpoint within bcr was not a prognostic factor in Ph(1+)CML. On the other hand bcr rearrangements were negative (bcr(－)) in 2 juvenile CML (JCML), 3 chronic neutrophilic leukemia (CNL), 9 chronic myelomonocytic leukemia (CMML), 8 polycythemia vera (PV), 15 essential thrombocythemia (ET) and 4 myelofibrosis (MF) patients. In 5 patients with Ph(1)-negative (Ph(1－)) CML/unclassifid chronic myeloproliferative disorders (UCMPD), 2 were bcr(+) and 3 were bcr(－), which strongly suggested the existence of Ph(1－)bcr(－)CML.
chronic myelocytic leukemia
variant Ph(1) chromosome
unclassified shronic myeloproliferative disorders