CD19 and leukemia: In particular, genes CD22, CD19, CD79A and HLA-DRA (Entrez IDs 4861, 5929, 5135 and 7978 respectively), which Haferlach et al. identified as members of a “virtual immunophenotype” (Fig. 3 of [38]) for leukemia classification, are all active genes in the most important FC (FC18).