Structural analyses of the loci involved in t(5;14) identify putative transcriptional cis-regulatory elements. (A) Localization of the translocation breakpoints on chromosome 5 (top) and on chromosome 14 (bottom). Vertical arrows indicate the location of the breakpoints. The number refers to the patient's number. The majority of chromosome 5 breakpoints is located in a 69-kb area between exons 20 to 25 (shown by vertical lines) of RANBP17. A horizontal arrow indicates the sense of transcription of the genes. The chromosome 14 breakpoints are spread over 842 kb downstream of BCL11B, in a region devoid of any obvious gene.^7,14  The nucleotide sequences of the breakpoints are presented in Figure S1. Note that the breakpoint of patient 1 is located in the 3′ untranslated region of TLX3. The chromosome 14 region that is juxtaposed in cis to the TLX3 gene in every t(5;14) patient characterized here is located between the breakpoints of patients 1 and 6. F1 indicates the breakpoint of a complex t(7;14;15) reported previously¹⁵  that allows the breakpoint to narrow the “critical” region to a 58-kb area indicated by a black rectangle. (B) DNAse1 mapping experiments in the chromosome-14 region predicted to contain transcriptional regulatory elements. (Top) Map of the 58-kb chromosome-14 area analyzed in this experiment, showing EcoRV (EV) and BamHI (BHI) sites and the probes used. The numbers refer to chromosome 14 genomic sequences (NCBI Build36; NCBI, Bethesda, MD). (Bottom) Southern blot analysis of DNAse1 hypersensitivity experiments using DND41 cells. Increasing concentrations of DNAse1 reveal 5 hypersensitive sites (the corresponding fragments are shown by arrows). The sizes of the germ-line fragments are indicated. Additional experiments are presented in Figure S2.