Detection of 11q23 (MLL) rearrangements in infant acute lymphoblastic leukemia

117 cases of infant acute lymphoblastic leukemia without Down syndrome (aged from 1 to 365 days) were included in the current study.Rearrangements of 11q23 (MLL) were revealed in 74 (63.2 %) patients. Among this group the most common rearrangement was t(4;11) q21;q23)/MLL-AF4 detected in 63.5 % cases, less frequently was found t(11;19)(q23;p13)/MLL-MLLT1 (in 18.9 % cases), t(10;11) p12;q23)/MLL-MLLT10 and t(1;11)(p32;q23)/ML L-EPS15 (each one in 6.8 %), t(9;11)(p22;q23)/MLL-MLLT3 in 2.7 %. Children under 6 months of age had significantly higher incidence of 11q23 (ML L) rearrangements in comparison with infants olde r than 6 months (84.0 % vs. 47.8 %, p &lt; 0.001). P atients with translocations 11q23 (ML L) more frequently had BI-A LL and less frequently BII-ALL than children without these rearrangements (p &lt; 0.001 f or both). Fusion gene transcript w as sequenced in 26 ML Lrearranged cases. Depending on breakpoint position within ML L and partner genes we detected 7 differ ent types of ML L-AF4 fusion gene transcript, 3 types of MLL-MLLT1, 2 types of MLL-EPS15. The most common fusion site within MLL gene was exon 11, detected in 14 (53.8 %) patients.</p