A high expression of CD49d (>30%) was found in 142/415 (34%) patients and was associated with progressive disease (advanced clinical stage, high serum lactate dehydrogenase or β2 -microglobulin levels; all p < 0·05) and aggressive disease biology (increased ZAP70 or CD38, unmutated IGHV, trisomy 12, mutations of NOTCH1 and SF3B1; all P < 0·05).