Clinical significance and frequency of the 11q23/MLL geneticmolecular alteration in Chilean infants with acute leukemia

Background Acute leukemia (AL) ill infants generally shows distinctive biol ogic features and has a poor prognosis. Aint: To Study the frequency of the cytogenetic alteration of 11q23 chromosome or the recombination of MLL gen e ill infants less than 18 months old, with acute leukemia. Patients and me thods. We analyzed 37 cases of AL ill infants less than 18 months of age di agnosed ill Chile from 1989 to 1999. The clinical features and cytogenetic/ molecular defects of 11q23MLL gene rearrangement and their influence ill pr ognosis were determined. Results: There were 18 cases of acute Lymphoblasti c leukemia (ALL) characterized by female Sex (67%) high presenting leukocyt e count (median 99 x109/L), blast cells with a CD10 negative phenotype (50% ) and 11q23/MLL rearrangement (39%). Molecular abnormalities Of 11q23 were significantly associated with adverse prognosis, with all event free surviv al (HF) of only 14 +/- 12%. Interestingly, infants with germ line 11q23 had a very good outcome with all EFS of 73 +/- 11% (P <0.025). There were 19 c ases of acute myeloblastic leukemia (AML) characterized ky mate sex (63%) h igh leukocyte count (median 93 x 109/L), FAB-MS morphology (53%) and 11q23/ MLL rearrangement (53%) EFS was very pool; 20 +/-9% and 33 +/-4% for rearra nged and germinal group respectively (p=NS), due to a high mortality rate d uring the first month of diagnosis. Conclusions: These findings demonstrate that Chilean ALL infants with 11q23 abnormalities have a very poor Prognos is, However those with germinal state can enjoy a prolonged disease free su rvival with the current treatment protocols (Rev Mid Chile2001; 129: 634-64 2).