The c-myc Gene Paradox in Burkitt’s Lymphoma Chromosomal Translocation

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The association of the human c-myc proto-oncogene on the long arm of chromosome 8 with the specific, consistent chromosomal translocations observed in Burkitt’s lymphoma (BL) has been established by a variety of studies. This association involves, in about 90% of cases, the immunoglobulin heavy (H) chain locus on chromosome 14 (14q32) whilst in the so-called variant BL the light (L) chain loci are involved (in about 5% of cases the lambda (λ) light chain locus on 22q11 and the remaining 5% the kappa (κ) light chain on 2pl2). In the predominant 8/14 translocations, the c-myc gene is included in the segment of chromosome 8 that translocates to chromosome 14 (Erikson et al. 1982; Davis et al. 1984) and the resultant proximity of c-myc and H chain constant region genes (in which the genes are arranged in the opposite transcription orientation) allows the orientation of the respective genes in relation to the chromosomal centromere (i.e. the c-myc gene is present on chromosome 8 with the 5′ end towards the centromere). Recently, studies of both types of variant BL translocation (i.e. t8/22 and t2/8) have shown that the breakpoint in these cases occurs to the 3′ side or downstream of the c-myc gene (Croce et al. 1983; Davis et al. 1984; Mollis et al. 1984).