Given that several proteins within the BCR signalling pathway are reported expressed at higher levels in CLL than in normal B cells14, that some of these proteins such as Btk and Syk are also therapeutic targets and that this pathway plays an important role in the pathogenesis of this disease, it is not unreasonable to postulate a correlation between expression of pathway proteins, BCR signalling strength and disease outcome. This evidence concerns the gene BTK and B-cell chronic lymphocytic leukemia.