Roos et al. found that shortened telomere length in chronic lymphocytic leukemia (CLL) patients is consistent with other classic biological factors of CLL, including unmutated immunoglobulin heavy chain variable region genes (UM-IGVH), positive CD38 and ZAP-70 (>30%), and short lymphocyte doubling time (<6 months) [40]. This evidence concerns the gene CD38 and B-cell chronic lymphocytic leukemia.