IGSF4 gene expression in pediatric AML as determined by gene expression arrays. Graphs showing the expression of probe set 209031_at, representing the IGSF4 gene, after log transformation. Bars represent the median expression in each group. (A) Significant differences are shown between patients with a t(9;11) (n = 26) and patients with another MLL rearrangement (MLL other, n = 42; 8.8 vs 7.4, P < .001) or AML patients without an MLL rearrangement (AML other, n = 192; 8.8 vs 6.8, P < .001). (B) Expression of probe set 209031_at with all groups divided on the basis of morphology, ie, FAB M5 versus other FAB-types (non-FAB M5). All cases with unknown FAB type were excluded from this analysis (t(9;11) n = 1, AML-other n = 10). We detected a significant difference for median expression within the patients with a t(9;11) (n = 21 vs n = 4; 8.9 vs 7.3, P = .001) and the patients with other MLL rearrangements (n = 23 vs n = 19; 7.8 vs 7.0, P = .009). This difference was not detected in the remaining patients without an MLL rearrangement (AML other, n = 16 vs n = 166; 6.8 vs 6.8, P = .20).