Clinical and molecular genetic characterization of wild-type MLL infant acute lymphoblastic leukemia identifies few recurrent abnormalities

Clinical and molecular genetic characterization of wild-type MLL infant acute lymphoblastic leukemia identifies few recurrent abnormalitiesWild-type MLL infant acute lymphoblastic leukemia (ALL) patients account for approximately 20% of all infant ALL cases.Although this group of patients generally fares better than MLL-rearranged infant ALL patients, their prognosis is still worse than that of non-infant pediatric B-ALL patients.Extensive characterization of this specific patient group largely remains unacknowledged.In this study, we aim to obtain a clinical and molecular profile of this patient group in order to find new opportunities to optimize treatment.We report on a large cohort of 78 wild-type MLL infant ALL samples using clinical parameters, array-comparative genomic hybridization analysis, and gene expression profiling.The frequency of DNA copy number variations and molecular genetic lesions in genes involved in Bcell development are lower in wild-type MLL infant ALL than older children with ALL.Wild-type MLL infant ALL presented with higher white blood cell (WBC) counts and a more immature immunophenotype than pediatric (noninfant) B-ALL patients.The strongest predictor of outcome in wild-type MLL infant ALL was the level of MEIS1 expression, which may indicate new opportunities for novel strategies in treating wild-type MLL infant ALL.Acute lymphoblastic leukemia (ALL) in infants (<1 year of age) is a rare but highly aggressive type of leukemia, typically characterized by the presence of MLL-rearrangements occurring in approximately 80% of these patients.1 *Other immunophenotypes included both acute undifferentiated and biphenotypic leukemias.WBC: white blood cell; NA: not applicable.