The chromosome 14 breakpoint in neoplastic B cells with the t(11;14) translocation involves the immunoglobulin heavy chain locus.

Abstract

Neoplastic cells were hybridized from a patient with chronic lymphocytic leukemia of the B-cell type, which carried a reciprocal chromosomal translation between chromosomes 11 (q13) and 14 (q32) with mouse plasmacytoma cells. The hybrid cells were studied for the presence, rearrangement and expression of the human Ig .mu. chain locus. The expressed .mu. chain gene is apparently located on the normal chromosome 14, whereas the 14q+ translocation chromosome carries the excluded Ig constant (C) region .mu. chain allele (C.mu.) but does not contain variable (V) region H chain genes (VH). The H chain joining region DNA (JH) of the excluded .mu. chain gene is on the 14q+ chromosome; the chromosomal break observed in the leukemic cells occurred in a chromosomal region within or 5'' of the JH region. Logically a gene, with the suggested name bcl-1, is located on band q13 of chromosome 11 and is activated by its translocation into close proximity with the rearranged H chain locus on chromosome 14q+, contributing to the neoplastic transformation of the B cells with the t(11;14) chromosomal translocation.