Burkitt's lymphoma variant translocations: distribution of chromosomal breakpoints and perturbated regulation of a mutated c-myc gene.

Abstract

Variant translocations in Burkitt’s lymphoma have the breakpoint of the chromosomal translocation 3’ of c-myc on chromosome 8 and 5’ of immunoglobulin kappa or lambda light chain constant genes on chromosome 2 or 22. The distance of the breakpoints to c-myc is variable. Ina few cases the breakpoints are localized within 10 kb 3’ of c-myc (BL37, KK124, and BL2) (Hollis et al. 1984, Denny et al. 1985, Showe et al. 1987). In the majority of cases the breakpoints are, however, at an unknown large distance from c-myc. Major structural alterations in c-myc were observed only in two cases with variant translocations. These represent duplications of the first exon (JBL2) (Taub et al. 1984) and of the coding part of c-myc (BL64) (Hartl and Lipp 1987). The duplication turned out to be constitutional in BL64, whereas in the case of JBL2 no normal tissue was available for analysis. Minor structural changes in the c-myc gene were found in all cases of variant translocations studied at the sequence level (LY47, KK124, BL2, BL64, BL60) (Rabbitts et al. 1984, Denny et al. 1985, Showe et al. 1987, Hartl and Lipp 1987, Strobl and Polack unpublished) and in a large panel of cell lines studied for restriction enzyme polymorphisms (Pelicci et al. 1986, Szajnert et al. 1987).