LEUKEMIA BREAKPOINT REGION IN 3Q21 IS GENE RICH

Rearrangements of the long arm of human chromosome 3, including recipr ocal translocations, inversions and deletion/duplication of bands 3q21 -3q26, as well as deletions of 3q21 and reciprocal translocations betw een 3q21 and other chromosomes, are well documented in leukemia. Previ ous studies showed that the breakpoints within 3q21 cluster within a 1 0-40 kb region but no candidate genes were described. In this work, we have identified partial cDNAs corresponding to five to nine new trans cripts from an 80 kb P1 clone that spans ten breakpoints. These transc ripts, with one exception, appear to be expressed only at low levels i n the set of cancer cell lines examined. Four transcripts are located between the previously mapped Ribophorin I gene and the most centromer ic breakpoint; three map directly within the 20 kb spanning nine indep endent breakpoints. These data (i) show that among characterized leuke mia breakpoint regions 3q21 is unusually gene rich, (ii) provide new c andidates for relevance to leukemia in 3q21, and (iii) suggest possibi lities for chromatin configuration effects. (C) 1997 Elsevier Science B.V.