Editorials and Perspectives haematologica| 2009; 94 (6)| 753| all of these studies have identified a number of genes whose differential expression distinguishes between aggressive and stable CLL. Among the genetic markers of poor prognosis, results from Stamatopoulos5 and from our group8 have consistently pointed to genes coding for proteins involved in the control of cell movement. This highlights the significance of topographical issues in disease progression and provides convincing evidence that CLL cells with enhanced motility are associated with aggressive disease. Independent confirmation of these results stems from data generated in patients, showing that a significant proportion of the leukemic clone proliferates and that proliferation occurs predominantly in lymphoid organs. 9 Furthermore, CLL cells characterized by the highest sensitivity to chemokines also express molecular markers associated with poor prognosis. 10 Lastly, histological analyses indicate that proliferating CLL cells are located in specialized areas in the bone marrow (BM) and in peripheral lymphoid organs. 11