t(2;18) and t(18;22) variant chromosomal translocations and bcl-2 gene rearrangements in human malignant lymphomas.

Most human follicular lymphomas bear the specific t(14;18) translocation that juxtaposes the 3' region of bcl-2 to the IgH gene on chromosome 14q+. In some rare cases, t(2;18) and t(18;22) translocations have been observed that involve bcl-2 and either Ig kappa or lambda genes. Strikingly, in these cases all the breakpoints on chromosome 18 are located in the 5' end the bcl-2 gene. These rearrangements are very similar to those recently found in a significant proportion of CLL. Thus, bcl-2 rearrangements in malignant lymphomas cluster in at least three regions: the so-called major breakpoint region (mbr) and minor cluster region (mcr) in more than 85% of t(14;18) translocation, and the newly characterized region 5' of the gene. We propose to call this new cluster region vcr (for variant cluster region).