BCR and B-cell chronic lymphocytic leukemia: These stereotypes, also referred to as CLL subsets, are defined by similarities in the BCR HC sequence, specifically by particular IGHV and Ig heavy chain junctional (IGHJ) genes and the complementarity-determining region (CDR)3 sequence created by variable, diversity, and junctional (VDJ) recombination (13, 15, 16).