Molecular findings in childhood leukemia in Brazil: high frequency of MLL-ENL Fusion/t(11;19) in infant leukemia.

Translocations involving chromosome 11q23 are frequently found in pediatric leukemia, especially in infants. The mixed lineage leukemia (MLL)-AF4 fusion/t(4;11) is mostly found in acute lymphoblastic leukemia (ALL) and MLL-AF9 fusion/t(9;11) in acute myeloid leukemia (AML). We study 441 consecutive new cases of childhood leukemia diagnosed in Brazil. Chromosomal translocation was determined solely by conventional polymerase chain reaction (PCR) in 72 out of 265 ALL and in 43 out of 103 AML. MLL-AF4 fusion/t(4;11) was detected in 3 out of 265 ALL and MLL-AF9 fusion/t(9;11) in 4 out of 103 of AML. MLL-rearrangements were presented in 7 out of 23 infant leukemia, whose 5 were MLL-ENL fusion/t(11;19). No fusion MLL-AF4 fusion/t(4;11) was found. Other translocation frequencies differed from that reported for an American population suggesting interethnic differences on chromosomal translocations frequencies in acute leukemia.