MicroRNA microarray disarray?

A paper in PNAS this week reporting that a signature of microRNA (miRNA) gene expression correlates with diagnosis and prognosis of B-cell chronic lymphocytic leukemias (CLLs) has drawn skepticism from others in the field.

Carlo M. Croce's group at the Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, report the use of a miRNA microarray, recently described, to identify significant differences in miRNome expression between CLL samples and normal CD5+ B cells. "The results were extremely exciting because they showed a signature of miRNA gene expression that correlates with diagnosis and prognosis of CLL," Croce told The Scientist.

Two signatures were found. One correlated with mutations in the variable region of the immunoglobulin gene—a good prognostic indicator, according to Croce. The other correlated with the deletion of chr13q14—a region containing two small miRNA genes that are downregulated in about 60% of CLL.

"There was only one common denominator between these two ...