Telomere disrupts, CLL progresses.

In this issue of Blood, Lin and colleagues address in detail the nature and severity of telomere disruption in chronic lymphocytic leukemia (CLL).1 Using sophisticated methods for telomere length determination, the authors show that critical telomere shortening occurs in a proportion of CLL samples and correlates with the presence of large-scale genomic rearrangements occurring in telomeric regions. These findings suggest that genomic instability associated with severe telomere shortening contributes to the progression of CLL and might represent a fairly common mechanism of tumor progression occurring in several human cancers.