The immunophenotyping data collected at the CCCL facilitated the qualitative subclassification of B-ALL cases based on the expression of CD10, IgM, and cytoplasmic Kappa/Lambda light chains (cyIgK/cyIgL), following the classification criteria established by the European Group for the Immunological Characterization of Leukemias (EGIL). The gene discussed is MME; the disease is precursor B-cell acute lymphoblastic leukemia.