Comparing the transcriptomes of ZAP-70+CD38+vs. ZAP-70−CD38− patients representing the extremes of the disease spectrum, we identified a panel of CLL subtype distinction genes, the majority of which was found to be over-expressed in the prognostically unfavorable ZAP-70+CD38+ subgroup [2], [3]. This evidence concerns the gene ZAP70 and B-cell chronic lymphocytic leukemia.