This study investigates the expression profiles of microRNAs (miRNAs) in human B-cell chronic lymphocytic leukemia (CLL) using a microarray containing hundreds of human miRNA probes. The researchers identified significant differences in miRNA expression between CLL samples and normal CD5+ B cells, with at least two distinct clusters of CLL samples associated with the presence or absence of Zap-70 expression, a predictor of early disease progression. Two miRNA signatures were also associated with the presence or absence of mutations in Ig variable-region genes or deletions at 13q14, respectively. These findings suggest that miRNA expression patterns have relevance to the biological and clinical behavior of CLL. The study highlights the importance of miRNAs in the pathogenesis of human B-cell malignancies and their potential as prognostic markers.This study investigates the expression profiles of microRNAs (miRNAs) in human B-cell chronic lymphocytic leukemia (CLL) using a microarray containing hundreds of human miRNA probes. The researchers identified significant differences in miRNA expression between CLL samples and normal CD5+ B cells, with at least two distinct clusters of CLL samples associated with the presence or absence of Zap-70 expression, a predictor of early disease progression. Two miRNA signatures were also associated with the presence or absence of mutations in Ig variable-region genes or deletions at 13q14, respectively. These findings suggest that miRNA expression patterns have relevance to the biological and clinical behavior of CLL. The study highlights the importance of miRNAs in the pathogenesis of human B-cell malignancies and their potential as prognostic markers.