IGHD and B-cell chronic lymphocytic leukemia: A major step forward occurred in 1998, when Chiorazzi’s group published the first comprehensive study confirming that the IGHV gene repertoire of CLL is restricted and also different from that of normal IgM+ B cells, with certain genes, such as IGHV1-69, IGHV4-34, and IGHV3-7, clearly over-represented in CLL.18 Pronounced restrictions were also recognized regarding the usage of IGHD and IGHJ genes.