Major breakpoint region

Fang JM, Firm WG, Hussong JW, et al. GDIO antigen expression correlates with the t(14 18)(q32 q21) major breakpoint region in diffuse large B-cell lymphoma. Mod Pathol. 1999 12(3) 295-300. 

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

Raghavan SC, Swanson PC, Ma Y, Lieber MR. Double-strand break formation by the RAG complex at the BCL-2 major breakpoint region is cleaved by the RAG complex. Nature. 2004 428 88-93. 

Figure 39-8 Schematic representation of the organization of the 6CL-2 gene and most frequent breakpoints on chromosome I8q2l involved in the t( 14 18).The 6CL-2 exons are represented as rectangles. MBR represents the major breakpoint duster region where approximately 50% to 60% of the breakpoints occur. MCR represents the minor breakpoint duster region where 20% to 25% of the breakpoints may be found.VCR represents the variant duster region where 5% to 20% of the breakpoints may be found.

Figure 39-14 Schematic representation of the BCR (22q 11) and ABL (9q34) genes involved in the t(9 22), which is characteristic of all CMLs and a subset of ALLs. The centromeric (cen) and teiomeric (tel) directions are indicated.The relative positions of the major breakpoint duster (M-BCR), the minor breakpoint duster (m-6CR), and the micro breakpoint duster regions (ft-BCR) are shown. The previously used alternative nomenclature for the BCR and ABL exons is included where relevant. In panel A, the exons of the BCR genes are depicted in black rectangles, and those of the ABL genes are depicted in white rectangles. In panel B, the configuration and varieties of the BCR-ABL chimeric fusions seen in CML are shown. In the lower part of panel B, the configuration and varieties of the BCR-ABL fusions seen in ALL are shown. The el-a2 transcript is most commonly detected in t(9 22)-positive ALL, while the b3-a2 and b2-a2 fusions are the most commonly detected in CML...

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. ... 

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