BCR and B-cell chronic lymphocytic leukemia: From the molecular point of view, M-CLL with neutral HCDR3 showed DJ footprints compatible with a more immature BCR repertoire associated with preferential usage of D(H)2 IGHV gene segments (53), in the absence of a biased use of JH4 gene segments, as found in M-CLL cases with negatively charged HCDR3 sequences, being biased use of JH4 gene segments a typical feature of more mature PB B lymphocytes (54).