Major breakpoint cluster region

CML patients characteristically exhibit relative and absolute monocytosis in peripheral blood reminiscent of chronic myelomonocytic leukemia. Another distinct but rare fusion that has been described in t(9 22)-positive CML is one that results in the formation of a large 230kDa fusion protein as a consequence of a fusion between exon 19 (c3) of BCJ and exon 2 (a2) of ABL. The BCR breakpoints for this fusion are located in the micro breakpoint cluster region (jX-BCl ) located between exons 19 and 20 (see Figure 39-14). The p230 fusion is characteristic of a peculiar form of CML with prominent neutrophilic proliferation. The clinical course of p230-positive CML is reportedly indolent in the majority of cases. ... 

MBR major breakpoint region MCR minor cluster region V variable segments D diversity segments J joining segments C constant region TE transcriptional enhancer... 

---