ZAP70 and B-cell chronic lymphocytic leukemia: Specifically, the markers ZAP70 (zeta-chain associated protein kinase 70kDa) and CD38 (cluster of differentiation 38) are used, given their previously demonstrated ability to predict IgVH (immunoglobulin heavy chain variable region) mutational status, a clinical phenotype commonly associated with differentiating between diagnoses of aggressive versus indolent CLL [5].