Kanduri M, Cahill N, Göransson H, et al. Differential genome-wide array-based methylation profiles in prognostic subsets of chronic lymphocytic leukemia. Blood. 2010;115(2):296-305.

On page 298 in the 14 January 2010 issue, the average difference in methylation index (MI) value applied between the immunoglobulin heavy-chain variable (IGHV) mutated and IGHV unmutated subgroups, 0.45, is incorrect. The correct MI value is 0.40. In “Methods,” the last sentence under the heading “Methylation array analysis” reads, “Consequently, an average difference in MI of 0.45 between the IGHV mutated and IGHV unmutated subgroups, 0.35 between the IGHV3-21 and IGHV mutated subgroups, and 0.35 between IGHV3-21 and IGHV unmutated subgroups was applied.” The sentence should have read, “Consequently, an average difference in MI of 0.40 between the IGHV mutated and IGHV unmutated subgroups, 0.35 between the IGHV3-21 and IGHV mutated subgroups, and 0.35 between IGHV3-21 and IGHV unmutated subgroups was applied.”

Furthermore, the number of genes identified as significantly differentially methylated between IGHV mutated and unmutated chronic lymphocytic leukemia (CLL) as well as the number of genes identified in the comparison between IGHV unmutated versus IGHV3-21 CLL and IGHV mutated versus IGHV3-21 CLL, respectively, are incorrect. The correct total number of genes identified as significantly differentially methylated between IGHV mutated and unmutated CLL is 96; the correct numbers of genes identified in the comparison between IGHV unmutated versus IGHV3-21 CLL and IGHV mutated versus IGHV3-21 CLL are 59 and 51, respectively. In “Results,” the fourth and fifth sentences under the heading “Methylation profiling of different prognostic subgroups of CLL” read, “Using highly stringent selection criteria (as detailed in “Methylation array analysis”), a total of 64 genes were identified as significantly differentially methylated between IGHV mutated and unmutated CLL (Figure 2A). Similarly, 60 and 31 genes were identified in the comparison between IGHV unmutated versus IGHV3-21 CLL and IGHV mutated versus IGHV3-21 CLL, respectively (Figure 2B-C).” The sentences should have read, “Using highly stringent selection criteria (as detailed in “Methylation array analysis”), a total of 96 genes (99 CpG sites) were identified as significantly differentially methylated between IGHV mutated and unmutated CLL (Figure 2A). Similarly, 59 genes (61 CpG sites) and 51 genes (52 CpG sites) were identified in the comparison between IGHV unmutated versus IGHV3-21 CLL and IGHV mutated versus IGHV3-21 CLL, respectively (Figure 2B-C).”