Semimethylation is a feature of Diffuse Large B-cell Lymphoma, and subgroups with poor prognosis are characterized by global hypomethylation and short telomere length

We studied the DNA methylation profiles of 93 LBCL cases: Diffuse large B-cell lymphoma not otherwise specified (DLBCL, n=66), High-grade B-cell lymphoma (n=7), Primary CNS lymphoma (n=8), and transformation of indolent B-cell lymphoma (n=12). One sample of normal GC B-cells from tonsils was included as a control. LBCL cases had a particularly aberrant semimethylated pattern with large intertumor variation and overall low hypermethylation. In cases treated with R-CHOP-like regimens, a high percentage of global hypomethylation was independently associated with worse disease-specific survival and progression-free survival. Genomic DNA from fresh frozen tissue samples were extracted using the AllPrep DNA/RNA mini kit (#80204, Qiagen, Hilden, GER). The DNA was bisulfite converted using the EZ DNA Methylation Kit (Zymo Research, Irvine, CA) and the Infinium MethylationEPIC BeadChip (Illumina, San Diego, CA), with coverage of >850 000 CpG sites, were used for genome-wide assessment of DNA methylation profiles. 96 LBCL samples and one normal GC B-cell sample are submitted. 3 LBCL samples (sample 94, sample 95, and sample 96) were excluded from the analysis after the normalization and pre-processing due to low tumor cell content.