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Updated: Mar 12, 2026

Isolation of Precursor B-cell Subsets from Umbilical Cord Blood
Published on: April 16, 2013
Lymphoblastic Leukemia With Mature B-Cell Phenotype in Infancy
John L Frater1, Jacqueline R Batanian, Dennis M O'Connor
1From the *Department of Pathology, Saint Louis University School of Medicine, St. Louis, Missouri; and †Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, Missouri.
Abstract:
Lymphoblastic leukemias with surface immunoglobulin light chain expression and L1/L2 blast morphology (French-American-British Classification) are rare. The poor prognosis of lymphoblastic leukemia in children under 1 year of age is attributed largely to rearrangements involving the mixed lineage leukemia (mll, also known as all1, htrx, trx1, or hrx) gene that occur with increased frequency in this population. Mll-rearranged cases with a mature B-cell phenotype are rare. The authors describe an infant with mature B-cell lymphoblastic leukemia with an mll rearrangement and L1/L2 cytomorphology and discuss the clinical, genetic, and immunophenotypic features in the context of previously reported cases.
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