Figure 6.

Application to childhood ALL with TCF3/PBX1 gene fusion. Segmentations of the expression maps of chromosomes 1 and 19 in 18 cases of ALL exhibiting the TCF3/PBX1 fusion oncogene (Ross et al data set) using different method parameters. Light grey: original gene scores. Dark blue: reconstructed expression bias profile. Top: λ_N = 2/5. Middle: λ_N = 2/15 Bottom: λ_N = 2/30. Key observations are as follows. (1) Most cases display over-expression in 1q distal to the PBX1 locus and under-expression over a ~1.6 Mb region on 19p distal to the TCF3 locus (translocation breakpoints indicated by vertical bars). The explanation for this finding is discussed in the Results section. (2) Reducing λ_N allows the algorithm to emphasize on larger regions, while suppressing smaller regions.